Dietary supplements are products that are intended to provide additional nutrients to the body or to supplement the diet.
They come in various forms, such as capsules, tablets, powders, and liquids, and can contain vitamins, minerals, herbs, amino acids, enzymes, or other ingredients. Dietary supplements are popular, with more than half of adults in the United States taking them regularly. However, there are concerns about their safety and efficacy, and consumers should be aware of the risks and benefits of using these products.
Reason for use
One of the primary reasons people take dietary supplements is to ensure they are getting enough of certain vitamins and minerals. This is especially important for people who have dietary restrictions, such as vegans or people with allergies or intolerances to certain foods. For example, vitamin B12 is found almost exclusively in animal products, so vegans may need to take a B12 supplement. Similarly, people with celiac disease or gluten intolerance may need to take a multivitamin that is free from gluten-containing ingredients.
Health and wellness
Another common reason people take dietary supplements is to improve their overall health, wellness or to target specific health conditions. For example, omega-3 supplements are often taken to support heart health, and probiotics are taken to support gut health. Some people also take supplements to manage specific health conditions, such as arthritis, migraines, or depression. However, it is important to note that not all supplements are effective for all people, and some may even be harmful.
There are many potential risks associated with taking dietary supplements. One risk is the potential for interactions with medications or other supplements. For example, St. John’s wort, a common herbal supplement used to treat depression, can interact with many prescription medications, including antidepressants, birth control pills, and blood thinners. Another risk is the potential for overdosing on certain nutrients. Vitamins and minerals can be toxic in large doses, and some supplements may contain levels that are much higher than the recommended daily intake.
The efficacy of dietary supplements is also a concern. While some supplements have been shown to be effective in certain populations, many have not been rigorously tested in clinical trials. In addition, the quality and purity of supplements can vary widely, with some products containing contaminants or undeclared ingredients. The U.S. Food and Drug Administration (FDA) does not regulate supplements as rigorously as it does drugs, which means that consumers cannot always be certain that the products they are buying are safe and effective.
Information is key
To reduce the risks associated with taking dietary supplements, it is important to be an informed consumer. The FDA recommends that consumers talk to their healthcare provider before taking any supplements, especially if they are pregnant or nursing, taking prescription medications, or have a chronic health condition. Consumers should also read supplement labels carefully, looking for information about the ingredients, dosage, and potential side effects. They should also look for supplements that have been tested and certified by third-party organizations, such as the United States Pharmacopeia or ConsumerLab.com.
However, it is important to remember that dietary supplements are not a substitute for a healthy, balanced diet. It is always best to obtain nutrients from whole foods whenever possible.
It is also important to be aware that dietary supplements can interact with prescription medications and cause harmful side effects. Before taking any new supplement, it is important to consult with a healthcare provider to ensure it is safe and appropriate for you.
Glossary of dietary supplements
- 26-deoxyactein A component of black cohosh. It belongs to the family of chemical compounds called triterpene glycosides.
- AMRM The Dietary Supplements Analytical Materials/Reference Materials Program of the Office of Dietary Supplements, National Institutes of Health.
signifies that the procedures used by the standards developer in connection with ANS meet the Institute's essential requirements for openness, balance, consensus, and due process.
- B vitamin A nutrient that is important for cell function. The B vitamins are biotin, folate, niacin, pantothenic acid, riboflavin (vitamin B2), thiamin, vitamin B6, and vitamin B12. The B vitamins make up the vitamin B complex.
- BRT Botanical Review Team of the Center for Drug Evaluation Research of the US Food and Drug Administration (FDA). BRT provides scientific expertise on botanical issues to CDER's reviewing staff and ensures consistent interpretation of FDA's "Guidance for Industry: Botanical Drug Products."
- Center for Food Safety and Applied Nutrition CFSAN, US Food and Drug Administration, Department of Health and Human Services. CFSAN is responsible for developing policy and regulations for dietary supplements.
- Dietary Guidelines for Americans Advice from the federal government to promote health and reduce the chance (risk) of long-lasting (chronic) diseases through nutrition and physical activity. The Guidelines are updated and published every 5 years by the US Department of Health and Human Services and the US Department of Agriculture.
- ER-negative Estrogen receptor negative (ER-). Having to do with breast cancer cells that do not have a protein (a receptor molecule) to which estrogen will attach. Breast cancer cells that are ER- do not need the hormone estrogen to grow and usually do not respond to hormone (antiestrogen) therapy that blocks these receptor sites.
- ER-positive Estrogen receptor positive (ER+). Having to do with breast cancer cells that have a protein (a receptor molecule) to which estrogen will attach. Breast cancer cells that are ER+ need the hormone estrogen to grow and will usually respond to hormone (antiestrogen) therapy that blocks these receptor sites.
- Federal Trade Commission FTC. A federal agency that protects consumers by preventing deceptive and unfair business practices. This includes unfair or deceptive advertising and marketing practices.
- Food Composition and Methods Development Laboratory FCMDL, US Department of Agriculture. The mission of FCMDL is to develop innovative measurement systems for the determination of food components that influence human health.
- HDL cholesterol Good cholesterol. HDL (high-density lipoprotein) cholesterol is a type of protein that carries excess cholesterol from the arteries to the liver to be removed from the body.
- Hamilton anxiety scale A rating system that is used to measure the severity of the symptoms of anxiety (including worrying, restlessness, fearfulness, trouble sleeping, poor concentration or memory, depression, aches and pains, shortness of breath, nausea, sweating, and impotence).
- IQ Intelligence quotient. A person’s score on a standardized intelligence test.
- IU International Unit. A measurement used to measure the activity of some vitamins and other biological substances (such as enzymes and hormones).
- Institute of Medicine IOM. A private nongovernmental organization that issues reports on biomedical science, medicine, and health as requested by government agencies, private industry, and foundations.
- International Unit IU. A measurement used to measure the activity of some vitamins and other biological substances (such as enzymes and hormones).
- Kupperman index A rating scale that is used to measure the severity of the symptoms of menopause, including hot flashes, tingling or crawling skin, difficulty sleeping, nervousness, melancholy, dizziness, weakness, joint or muscle pain, headache, and abnormal heart beat.
- LDL cholesterol Low-density lipoprotein cholesterol. A type of protein that carries cholesterol to many tissues throughout the body. High levels of LDL cholesterol increase the risk of coronary heart disease. Also called bad cholesterol.
- National Center for Complementary and Alternative Medicine NCCAM explores complementary and alternative healing practices in the context of rigorous science, trains CAM medicine researchers, provides accurate information about CAM, and helps the public and health professionals understand which CAM therapies have been proven to be safe and effective.
- National Formulary of the United States Pharmacopeia NF is a book of public pharmacopeial standards. It contains standards for medicines, dosage forms, drug substances, excipients, medical devices, and dietary supplements.
- Physicians' Health Study One of two long-term studies conducted to see whether the long-term use of aspirin or various nutritional supplements such as beta-carotene, vitamins C and E, and multivitamins can prevent heart disease, cancer, and age-related eye diseases in men in the United States.
- Retinol Activity Equivalent RAE. A measure of the content and activity of vitamin A in foods.
- SPF Sun protection factor. A scale for rating the level of sunburn protection in sunscreen products. The higher the SPF, the more sunburn protection it gives.
- World Health Organization WHO. An agency of the United Nations that is concerned with worldwide health.
- abetalipoproteinemia A rare inherited disease in which the intestine cannot absorb fats and fat-soluble vitamins from food. It is associated with fatty stools, diarrhea, nerve problems, and eye disease.
- absorption In nutrition, the process of moving protein, carbohydrates, fats, and other nutrients from the digestive system into the bloodstream. Most absorption occurs in the small intestine.
- acid reflux A condition in which stomach acid leaks backwards into the esophagus (the muscular tube through which food passes from the throat to the stomach), causing heartburn and irritating the lining of the esophagus.
- acne A sometimes severe skin condition that commonly occurs on the face, neck, back, and chest and includes whiteheads, blackheads, and pimples. Severe acne may be painful and can leave permanent deep scars.
- actein A component of black cohosh. It belongs to the family of chemical compounds called triterpene glycosides.
- acute Sudden, severe, and not long lasting.
- additive effect When the combination of two or more drugs, dietary supplements, or other therapies produces a greater result than one drug, dietary supplement, or therapy given alone. For example, combining valerian with alcohol may have a stronger sedative effect than valerian by itself would produce.
- adenoma A type of tumor that is benign (not cancer).
- administration The process of giving a person a medicine or dietary supplement by mouth, by vein, on the skin, or by another route. For example, a 14-day administration of valerian extract.
- adulterate To make unsafe or impure by using contaminated or unneeded ingredients; using a strength or quality that is less than claimed; leaving out or substituting key ingredients; or using inferior manufacturing, processing, packaging, or storage procedures.
- adverse effect An unwanted side effect.
- adverse response An unwanted or harmful reaction to treatment.
- age-related macular degeneration AMD. An eye disease that results in a loss of central, "straight-ahead" vision. AMD is the leading cause of vision loss in older Americans.
- agent In medicine, a drug, dietary supplement, other substance, or procedure that is used in diagnosing, screening, preventing, or treating a disease.
- alcoholic A person who is not able to stop drinking once he or she has begun, needs to drink larger amounts of alcohol to get high, and suffers withdrawal symptoms (such as nausea, sweating, shakiness, and anxiety) after stopping drinking.
- alpha-carotene A substance found in colorful fruits and vegetables such as pumpkin, carrots, winter squash, and tangerines. It is a carotenoid that can be made into vitamin A by the body.
- alpha-tocopherol equivalent A unit of measure used to compare the effects of different forms of vitamin E with the effects of alpha-tocopherol, the most active form of vitamin E.
- alpha-tocopherol transfer protein A substance made in the liver that attaches to vitamin E (alpha-tocopherol), carries vitamin E to the body's tissues, and helps vitamin E stay at a normal level in the body.
- alpha-tocopherol The form of vitamin E that is found in the largest amount in humans and is the most active form of vitamin E. It is an antioxidant.
- alternative medicine A group of diverse medical and health care systems, practices, and products that are used in place of conventional medicine.
- amino acid A chemical building block of protein.
- anemia A condition in which the number of red blood cells in the blood, or the amount of hemoglobin in them, is lower than normal, causing a condition in which red blood cells are not able to supply enough oxygen to all the tissues in the body. Hemoglobin is the substance in red blood cells that carries oxygen to your body's cells.
- anencephaly A condition in which a baby is born without most of a brain and skull. The brain may not be covered by bone or skin. Babies born with this condition do not survive more than a few hours or days. Anencephaly belongs to the group of disorders called neural tube defects.
- angiotensin receptor blocker A medication that relaxes and opens up blood vessels. This lowers blood pressure so the heart doesn’t have to work as hard to pump blood.
- animal study A laboratory test using animals to study the development and course of human diseases, and to test the safety and effectiveness of new treatments before they are given to humans.
- anorexia Not feeling hungry or wanting to eat food to an unusual extent.
- anthocyanins A group of pigments that naturally occur in some plants and produce the pink, red, and violet colors of fruits, leaves, and flowers. Berries, cherries, red wine, eggplant, red cabbage, and red and purple grapes are sources of anthocyanins.
- antibiotic A drug used to treat infections caused by bacteria and other microorganisms.
- anticoagulant A drug or other substance that stops blood clots from forming. Also called a blood thinner.
- anticonvulsant A drug that prevents, reduces, or stops convulsions or seizures.
- antiestrogen A substance that blocks the effects of estrogens (a family of hormones that helps develop and maintain female sex characteristics and the growth of long bones).
- antioxidant A substance that protects cells from damage caused by free radicals (compounds formed during the metabolism of oxygen). It may help prevent the development of some chronic diseases such as cancer. Antioxidants include beta-carotene; lutein; lycopene; vitamins A, C, and E; selenium; and zinc.
- apathy Having no emotion, interests, or concerns.
- aqueous Having to do with water.
- association A relationship between two conditions or states such that if one is present, the other is likely to be present as well. An association between two conditions or states, however, does not necessarily imply a cause and effect relationship. The terms association and relationship are often used interchangeably.
- ataxia Loss of muscle coordination.
- atherosclerosis A condition in which certain blood vessels (arteries) are clogged and have hardened. Atherosclerosis is caused by fat and cholesterol deposits (plaque) that block blood flow to certain parts of the body. It increases a person's chance (risk) of having a heart attack, stroke, kidney damage, or other diseases involving the arteries.
- atrophic gastritis A long-lasting (chronic) condition in which the linining of the stomach is inflamed. Gradually the lining wastes away, destroying the glands that make stomach acid.
- atrophy A weakening, decrease in size, or wasting away of a tissue, organ, or part of the body. For example, the muscles of a leg that has been in a cast for some time will atrophy because they are not being used, causing them to become smaller and weaker.
- attention deficit hyperactivity disorder ADHD. A common mental disorder that usually develops before age 7 and may continue into adulthood. Symptoms include inattention, excessive impulsiveness, and/or inability to remain still and quiet.
- autoimmune disease A condition in which the body recognizes its own tissues as foreign and directs an immune response against them.
- bacteria Single-celled organisms that are too small to be seen without a microscope. Bacteria are found everywhere and may be helpful or harmful.
- barbiturate A category of drug used to treat seizure disorders, insomnia, and anxiety and to calm patients before surgery. It belongs to the family of drugs called central nervous system depressants.
- bariatric surgery An operation on the stomach and/or intestines to help patients with extreme obesity lose weight. Some types of bariatric surgery limit the amount of food your stomach can hold. Other types of surgery change how food is digested, which stops some calories (and nutrients, such as vitamins) from being absorbed.
- benzodiazepine A category of drug used to treat seizure disorders, insomnia, anxiety, alcohol withdrawal, and muscle spasms, and to calm patients before surgery. It belongs to the family of drugs called central nervous system depressants.
- beta-carotene A carotenoid found in carrots, cantaloupe, apricots, sweet potatoes, pumpkin, winter squash, mangos, collard greens, spinach, kale, broccoli, and other orange, red, and dark green fruits and vegetables.
- beta-cryptoxanthin A substance found in citrus fruit, peaches, and apricots. It is an antioxidant. Beta-cryptoxanthin is one of a group of carotenoids that can be made into vitamin A in the body.
- bias In a clinical trial, the result of a flaw in the study design or method of collecting or interpreting the study information that can lead to incorrect conclusions.
- bile acid sequestrant A type of medication that is used to treat high cholesterol.
- binder An inactive ingredient (one that has no medicinal effect on the body, such as starch, salt, or sugar) used to hold together the contents of a pill or tablet.
- bioavailability The amount of a nutrient that reaches the body's tissues after it is eaten.
- biologic product A substance made from biological (living) sources and used to prevent, treat, or cure disease or injury. Examples include antibodies, vaccines, and blood products.
- biological activity An effect on life processes. For example, the biological activity of a vitamin means the effect it has on specific life processes in the body.
- biotin A nutrient that is needed by the body to change carbohydrates, fats, and amino acids into energy and the basic materials needed for important life processes. It belongs to the group of vitamins called the vitamin B complex. Biotin is found in some foods, including egg yolk, liver, and yeast.
- bladder cancer Uncontrolled growth of abnormal cells in the bladder (the organ that stores urine).
- blood sugar The main source of energy used by the body's cells. Blood sugar comes from food and is made by the liver, and is carried to the cells through the bloodstream. Also called blood glucose.
- blood vessel A tube through which blood circulates in the body. Blood vessels include a network of arteries, arterioles, capillaries, venules, and veins.
- blood-brain barrier A network of specialized cells that prevents certain substances, including many toxins and potentially harmful substances, from leaving the blood vessels and entering the brain.
- blue cohosh A plant that has been used to treat menstrual disorders and to start labor. It may be unsafe and should not be confused with black cohosh. Latin name: Caullophylum thalictroides.
- botanist A scientist who studies the biology of plants.
- caffeic acid A component of black cohosh.
- calcium carbonate A chemical compound naturally found in chalk, some seashells and other substances. Calcium carbonate is used in antacid drugs to treat indigestion and as a source of calcium to supplement the diet.
- calcium A mineral found throughout the body. Calcium is needed for healthy bones and teeth, for nerves and enzymes to function properly, and for blood clotting. Calcium is found in some foods, including milk, yogurt, and cheese, and in Chinese cabbage, kale, broccoli and fortified foods, such as many drinks, tofu, and cereals.
- cancer survivor A person with cancer, from the time he or she is diagnosed through the balance of his or her life.
- capsule A gelatin shell containing a dose of medicine, a vitamin, or other dietary supplement.
- carcinogen A substance that causes cancer.
- cardiac arrest A condition in which the heart suddenly stops beating.
- cardiac Having to do with the heart.
- cardiovascular disease CVD. A general term referring to disorders of the heart and blood vessels. CVD includes coronary artery disease, heart failure, atherosclerosis, high blood pressure, peripheral artery disease, and stroke.
- cardiovascular event A heart attack, stroke, or other occurrence that damages the heart or blood vessels.
- cardiovascular system The heart, blood, and blood vessels.
- case report A detailed record of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some information about the patient (such as age, gender, and ethnic origin).
- cataract A condition in which the lens of the eye becomes cloudy. Symptoms include blurred, cloudy, or double vision; sensitivity to light; and difficulty seeing at night. Without treatment, cataracts can cause blindness. Cataracts occur in people of all ages but are most common in the elderly.
- cell differentiation The process during which young, immature (unspecialized) cells take on individual characteristics and reach their mature (specialized) form and function. For example, unspecialized cells differentiate to become nerve cells, muscle cells, blood cells, or other specialized tissue cells.
- cell division The method by which a single cell divides to create two cells. This is a continuous process that allows a population of cells to increase in number or remain the same in number.
- cell line Cells of a single type that have been adapted to grow and divide in the laboratory and are used in research.
- cell membrane An envelope that contains the contents of a cell and controls what passes into and out of the cell.
- cell study A research tool in which individual units (cells) that make up the tissues of an animal or human body are studied outside of the body to find out if a drug or other treatment is likely to be safe and useful in the body. Cell studies are usually completed before testing is done in humans.
- cell The individual unit that makes up the tissues of the body. All living things are made up of one or more cells, which are the smallest units of living structure capable of independent existence.
- central nervous system depressant A medication that changes brain function and causes drowsiness. It may be used in anesthesia. Also called CNS depressant.
- central nervous system disorder A disease or condition that affects the brain, the spinal cord, and the ability to think, move, see, hear, taste, smell, or touch.
- chamomile The flower of this herb is used in some cultures for its calming effect, to promote sleep, and as a treatment for indigestion. It is being studied in relieving chronic pain in children with bowel disorders. Latin names: Matricaria recutita and Anthemis nobilis.
- chemoprevention The use of drugs, vitamins, or other substances to try to reduce the risk of, or delay the development or recurrence of, cancer.
- chemotherapy A chemical that kills bacteria, viruses, fungi, or tumor cells. It usually refers to drugs used in cancer treatment.
- chronic disease A condition that is continuous or recurrent, is not easily cured, and cannot be passed from person to person. Examples of chronic diseases include heart disease, diabetes, and asthma.
- chronic Happening for a long time, persistently, or repeatedly.
- cimicifugin A resin (a component of some plants) found in black cohosh.
- cimicifugoside A component of black cohosh. It belongs to the family of chemical compounds called triterpene glycosides.
- cirrhosis A condition in which damaged liver cells are replaced with scar tissue, making it progressively more difficult for the liver to function properly.
- clarity Clearness.
- clinical trial A type of research study that uses volunteers to test the safety and efficacy (the ability to produce a beneficial effect) of new methods of screening (checking for disease when there are no symptoms), prevention, diagnosis, or treatment of a disease. Also called a clinical study.
- cobalt An organic substance found in the earth and needed in very small amounts. It is also a necessary component of vitamin B12. A cobalt deficiency leads to anemia; too much cobalt can lead to a greater than normal number of red blood cells.
- cognition The intellectual and mental ability to be aware, think, learn, imagine, remember, reason, have perceptions, and make judgments.
- cognitive function Mental awareness and judgment.
- cognitive skills Mental and intellectual capabilities such as language, reading, math, reasoning, and critical thinking.
- collagen A strong, flexible protein found in cartilage, tendons, bone, skin, and other connective tissue.
- colon cancer Uncontrolled growth of abnormal cells in the large intestine (the tube-like organ connected to the small intestine at one end and the anus at the other).
- colorectal cancer Uncontrolled growth of abnormal cells in the colon (the longest part of the large intestine) and/or the rectum (the last several inches of the large intestine before the anus).
- columnar cell A type of cell that lines the internal and external surfaces of the body.
- commercial preparation A product such as a drug or dietary supplement made in large quantities to be sold.
- common cold A nose and throat infection caused by a virus. Symptoms include runny nose, sneezing, congestion, sore throat, and cough.
- complaint In medicine, a disorder, disease, or symptom.
- complementary and alternative medicine A group of diverse medical and health care systems, practices, and products that are not presently considered to be part of conventional medicine.
- complementary medicine A group of diverse medical and health care systems, practices, and products that are used together with conventional medicine.
- complication In medicine, an illness or condition that occurs while a patient has a disease. The complication is not a part of the disease, but may be a result of the disease or may be unrelated.
- compound In pharmacy, a substance that contains more than one ingredient.
- conception In biology, the fertilization of an egg by a sperm that begins a pregnancy.
- congenital A mental or physical condition that a baby is born with. It may be hereditary (passed from parent to child through information in the genes), or it may occur while the fetus is developing in the womb, or it may be a combination of both.
- conjugated estrogen A type of female hormone that is made from the urine of pregnant horses or from plants. It is used in estrogen replacement therapy, and to treat the symptoms of menopause, osteoporosis in women who have been through menopause, advanced breast cancer, and some types of advanced prostate cancer.
- connective tissue Cells that work together to protect and support the body’s muscles, joints, organs, skin, and other tissues. Examples of connective tissue include cartilage, fat, blood, and bone.
- consensus A general agreement.
- constipation A condition in which stool becomes hard, dry, and difficult to pass and bowel movements happen infrequently. Other symptoms may include painful bowel movements and feeling bloated, uncomfortable, and sluggish.
- constituent A component, part, or ingredient of a larger whole. For example, valerenic acid and valepotriate are constituents of the dietary supplement valerian.
- consume To eat or drink.
- control group In a research study or clinical trial, the group that does not receive the new treatment being studied. This group is compared with the group that receives the new treatment, to see whether the new treatment works.
- conventional drug A currently accepted and widely used medicine for a certain type of disease, based on the results of past clinical research.
- conventional food Edible substances, excluding organic food, genetically modified food, functional food, and dietary supplements.
- copper In nutrition, a mineral the body needs (along with iron) to make red blood cells. Copper also helps keep the immune system, blood vessels, nerves, and bones healthy. Copper is found in some foods, including oysters and other shellfish, whole grains, beans, nuts, potatoes, organ meats, dark leafy greens, and dried fruits.
- cornea The clear dome-shaped surface covering the front of the eye.
- cornification The changing of cells that line the internal and external surfaces of the body into an outer layer of flat cells that look like fish scales under a microscope). Also called keritinization.
- coronary artery A blood vessel that supplies blood and oxygen to the heart.
- coronary heart disease A disease in which the blood vessels (coronary arteries) that carry blood and oxygen to the heart are narrowed or blocked, which can cause chest pain, shortness of breath, and heart attack. It is usually caused by a build-up of fat and cholesterol deposits inside the arteries (atherosclerosis).
- cruciferous vegetable A type of vegetable including arugula, bok choy, broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, mustard greens, radishes, rutabaga, turnips and watercress.
- cure To heal or restore health; a treatment to restore health.
- cytology The study of cells using a microscope (a device that uses a combination of lenses to make enlarged images of tiny objects).
- cytotoxic Cell-killing.
- dairy food Milk and products made with milk, such as buttermilk, yogurt, cheese, cottage cheese, and ice cream.
- data Facts and information.
- day 0 Sometimes used to indicate the first day of treatment.
- deciliter dL. A unit of volume in the metric system equal to one-tenth of a liter (about two-tenths of a pint).
- decoction A substance made by simmering some types of roots, bark, and berries in water to extract their desired ingredients. It is simmered for a longer time than that needed to make tea and may be drunk hot or cold.
- deficiency An amount that is not enough; a shortage.
- degeneration A condition in which tissues in the body lose their ability to function properly.
- delayed development Failure of a child to reach physical or behavioral milestones (such as rolling over, crawling, walking, and talking) at expected ages.
- dementia Damaged brain function (thinking, learning, making decisions, remembering) that worsens over time. It disrupts activities of daily living such as bathing, dressing, and walking.
- deoxyribonucleic acid DNA. The molecules inside cells that carry genetic information and pass it from one generation to the next.
- derivative In chemistry, a compound made from or related to another compound.
- diabetes A disease in which blood sugar (glucose) levels are high because the body is unable to use glucose properly. Diabetes occurs when the body does not make enough insulin, which helps the cells use glucose, or when the body no longer responds to insulin.
- diagnose The process of using signs and symptoms to identify a disease.
- dialysis The process of filtering the blood when the kidneys are not able to cleanse it.
- diarrhea Loose, watery stools.
- diarrheal infection A disease in which viruses, bacteria, or parasites invade the body and multiply, causing abdominal pain, cramping, and frequent watery bowel movements.
- diazepam A drug that is used as a sedative and muscle relaxant, and to treat anxiety and epileptic seizures.
- digestion The process the body uses to break down food into simple substances for energy, growth, and cell repair.
- digestive disorder An abnormal condition affecting any part of the digestive tract (mouth, esophagus, stomach, small and large intestines, rectum and anus) or organs involved in digestion (such as the stomach, liver, pancreas, or gallbladder). Also called digestive disease.
- digestive tract The large, muscular tube that extends from the mouth to the anus, in which hormones, enzymes, and the movement of muscles work together to digest food. Also called the gastrointestinal (GI) tract.
- disability A physical or mental impairment that significantly limits a person's ability to walk, see, hear, speak, breathe, learn, work, or take care of oneself.
- disease progression The way a medical condition develops over time.
- disorder In medicine, a disturbance of normal functioning of the mind or body. Disorders may be caused by genetic factors, disease, or trauma.
- disorientation A mental state marked by confusion about time, place, or who one is.
- distal ileum The end of the small intestine that attaches to the large intestine.
- distress Mental or physical pain or suffering.
- diuretic A drug or other substance that increases the amount of urine made by the body.
- dose The amount of medicine or other substance taken at one time or over a specific period of time.
- double-blind Describes a clinical trial in which neither the researcher nor the patient knows which of several possible therapies the patient is receiving.
- drug Any substance (other than food) that is used to prevent, diagnose, treat, or relieve symptoms of a disease or abnormal condition. Also, a substance that alters mood or body function or that can be habit-forming or addictive, especially a narcotic.
- duration The length of time that something lasts.
- echinacea A plant that is native to North America. Traditionally, it has been used for colds, flu, and other infections.
- edema Swelling caused by excess fluid in the body. Edema often affects the hands, arms, feet, ankles, legs, hands, and arms.
- effectiveness In medicine, the ability of an intervention (for example, a drug, surgery, or a dietary supplement) to produce the desired beneficial effect under the usual conditions of care by a health care provider.
- efficacy In medicine, the ability of an intervention (for example, a drug, surgery, or dietary supplement) to produce the desired beneficial effect under the best possible conditions of care, such as a clinical trial.
- electrolyte In the body, a dissolved mineral (such as sodium, potassium, chloride, or calcium) that helps control the amount of water in the blood, inside the cells, and in the spaces between the cells, and helps control the way cells work (such as moving nutrients into cells and moving wastes out of cells).
- endocrine system Hormone-producing glands that affect growth and development, hunger, metabolism (chemical changes in the body), sleep, sexual function, and mood. The endocrine system includes the thyroid gland, pituitary gland, adrenal gland, parathyroid glands, adrenal glands, pancreas, ovaries, and testicles.
- endometrium A layer of tissue that lines the uterus.
- endpoint A specific outcome measured in a clinical trial that is used to judge how well the treatment works (treatment efficacy). For example, the endpoint measured in a clinical trial may be weight loss, quality of life, or survival.
- enriched When certain nutrients (such as vitamins and minerals) have been added to a food product to replace nutrients that may be lost during processing or storage. For example, white flour is enriched with thiamin, riboflavin, niacin, and iron because those nutrients are lost when grain is made into flour. Folic acid is also added to enriched flour.
- enzyme A protein that speeds up chemical reactions in the body.
- eosinophil A type of white blood cell.
- epidemiologic study Research that examines the patterns, causes, and control of a disease in a population of people.
- epithelium A thin layer of tissue that covers organs, glands, and other structures within the body.
- esophageal cancer Uncontrolled growth of abnormal cells in the esophagus (the hollow muscular tube that moves food and liquid from the throat to the stomach). Cancer starts in the mucous membrane lining the inside of the esophagus and spreads outward through the layers of connective tissue and muscle as it grows.
- esophagus The muscular tube through which food passes from the throat to the stomach.
- essential In nutrition, essential nutrients are ones that we must consume for good health because our bodies cannot make them. Essential nutrients include vitamins and minerals.
- esteem Admiration, regard, respect, and value.
- ester A chemical compound made by the reaction between an alcohol and an acid.
- estradiol A form of the hormone estrogen.
- estriol A form of the hormone estrogen.
- estrogen receptor binding assay ER binding assay. A laboratory test to determine the presence of a protein found on cells of female reproductive tissue, some other tissues in the body, and some cancer cells. The hormone estrogen will attach (bind) to the receptors inside the cells and may cause the cells to grow.
- estrogen A hormone (a chemical made by the body that controls the actions of certain cells or organs) that is needed to develop and maintain female sex characteristics and the growth of long bones. Estrogens are also made in the laboratory and are used in birth control and to treat symptoms of menopause, menstrual disorders, and osteoporosis.
- ethanol A type of alcohol. Also called ethyl alcohol or grain alcohol.
- evidence Information used to support the use of a particular screening procedure, treatment, or preventive measure. In medicine, evidence needed to determine effectiveness is provided by laboratory research, clinical trials, and other studies.
- excitatory neurotransmitter A chemical that increases the number of messages sent between nerve cells (neurons). For example, acetylcholine is an excitatory neurotransmitter that is involved in wakefulness, attentiveness, anger, aggression, muscle contraction, release of hormones, and other actions.
- expert opinion In medicine, the judgment of a respected healthcare professional, based on clinical experience or reports of expert committees. Expert opinions are important when results of controlled clinical trials and other scientific studies are not available to provide health care recommendations.
- extended-release In medicine, pills and capsules that release a drug in the body slowly over time.
- extract A substance made by soaking an herb in a liquid that removes specific types of chemicals. The liquid can be used as is or evaporated to make a concentrate or a dry extract for use in capsules or tablets.
- failure to thrive A condition in which infants and children are dramatically smaller or shorter than other children of the same age and gender, and physical, mental, and social skills are significantly delayed. Causes include medical disorders, environmental factors, malnutrition, and neglect.
- fat soluble Able to be dissolved in fat.
- fatal Deadly; causing death.
- fatigue Extreme tiredness and an inability to function due to lack of energy.
- fetal Having to do with a fetus (the developing human from 7 to 8 weeks after conception until birth).
- fetus The developing human from 7 to 8 weeks after conception until birth.
- fibrocystic breast disease A common condition in which the breasts feel bumpy, tender, and painful, especially before a menstrual period.
- filler An inactive ingredient (one that has no medicinal effect on the body, such as lactose or starch) that is used to provide consistency and uniformity in the size and weight of a pill or tablet.
- flavanols Substances that naturally occur in some plants such as tea, cocoa, red grapes, berries, apples, and red wine. Also called flavan-3-ols.
- flavanones Substances that naturally occur in some plants, especially citrus.
- flavonoids Substances that naturally occur in many plants. Green tea, cocoa, coffee, red wine, berries, apples, citrus fruit, and cruciferous and colorful vegetables contain significant amounts of flavonoids. Plant foods contain more than 6,000 flavonoids, including flavanols, flavones, flavonols, flavanones, anthocyanidins, flavan-3-ols, and isoflavones.
- flavonols Substances that naturally occur in some plants, such as apples, apricots, beans, broccoli, cherries, cherry tomatoes, cranberries, kale, leeks, pears, onions, red grapes, and tea. Flavonols include quercetin, myricetin, and kaempferol.
- folic acid The form of folate (a B vitamin occurring naturally in food) that is manufactured and used in supplements and fortified foods.
- follicle-stimulating hormone FSH. A hormone made by the pituitary gland (an organ at the base of the brain) that is used in reproduction and in making estrogen and sperm.
- fortified When nutrients (such as vitamins and minerals) are added to a food product. For example, when calcium is added to orange juice, the orange juice is said to be "fortified with calcium". Similarly, many breakfast cereals are "fortified" with several vitamins and minerals.
- fracture A break, for example, a bone fracture.
- fragile Easily broken.
- fukinolic acid A component of black cohosh.
- functional food A conventional or modified food or ingredient that provides a health benefit (such as a lowered risk of osteoporosis) in addition to the basic nutritional functions of the food. Examples include whole, fortified, enriched, and enhanced foods.
- gamma aminobutyric acid GABA. A chemical found naturally in plants and animals. It stops nerve cells from communicating with each other and decreases electrical activity and nerve impulses in the brain. At high levels, GABA may cause a lack of coordination, sedation, and anesthesia.
- gastric cancer Uncontrolled growth of abnormal cells in the stomach that spreads through the outer layers of the stomach as it grows.
- gastric juice The digestive fluid made by the stomach. It contains hydrochloric acid, enzymes, intrinsic factor, and mucus.
- gastric Having to do with the stomach.
- gastroesophageal reflux disease GERD. A condition in which stomach acid leaks back into the esophagus because the muscle between the stomach and the esophagus does not close properly. It causes frequent heartburn and can lead to more serious health problems such as ulcers, swallowing difficulties, and cancer.
- gastrointestinal tract The large, muscular tube that extends from the mouth to the anus, where the movement of muscles and release of hormones and enzymes digest food.
- gastrointestinal GI. Having to do with the gastrointestinal tract (the large, muscular tube that extends from the mouth to the anus, where the movement of muscles and release of hormones and enzymes digest food).
- gene mutation A change in the DNA that makes up a gene. Mutations can occur when a cell divides and there are errors in the way the DNA is copied. Mutations can also be caused by exposure to certain chemicals and radiation, and from infections. Some gene mutations are passed from parents to their children. Others occur during a person’s lifetime.
- gene-modified Cells that have been altered to contain different genetic material than they originally contained.
- gene The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.
- genetic disorder A disease or disorder caused by an alteration or variation (mutation) in a gene or group of genes in the cells of an individual. Examples of genetic disorders include breast cancer, cystic fibrosis, Parkinson's disease, and celiac disease. They can be inherited or can occur without a known cause.
- genetically modified food Food made from plants or animals whose genes have been changed in the laboratory. These changes may increase crop yields, control insects and weeds, or improve nutritional content. Also called genetically engineered food.
- genetics Heredity passed from parent to offspring. Also, the identification and study of genes within an organism, their function in normal development, the consequences of gene alteration or variation (mutation), and potential treatments for genetic diseases.
- genus The name of a category that is part of the scientific classification of all organisms. Genus is located in the classification system after kingdom, phylum, class, order, and family and before the subclassification of species. Humans, for example, belong to the genus Homo and the species Homo sapiens.
- ginger The root of this plant has been used in cooking and in some cultures to treat nausea, vomiting, and certain other medical conditions. It is being studied in the treatment of nausea and vomiting caused by cancer chemotherapy. Latin name: Zingiber officianale.
- gland A small organ that makes and releases a substance such as sweat, tears, saliva, milk, a hormone, or substances that aid in digestion.
- glucosamine Glucosamine sulfate is found naturally in the fluid that surrounds your joints. It is also made from the shells of shrimp, lobsters, and crabs, and can be made in the laboratory. Some people use glucosamine to help prevent arthritis pain.
- glutamine A chemical that increases the number of messages sent between nerve cells. It is thought to be involved in learning and memory.
- gluten A protein found in wheat, rye, and barley. Eating gluten damages the small intestine in people who have celiac disease (also called gluten intolerance, gluten-sensitive enteropathy, and sprue) and can cause abdominal pain, gas, diarrhea, and other symptoms.
- glycoside A chemical compound that is made from a sugar molecule in the body or in a laboratory.
- goiter An enlarged thyroid gland. A goiter is caused by too little iodine in the diet or by other conditions, such as a growth on the thyroid or a gland that makes too much or not enough hormones.
- gram g. A measure of weight. It is a metric unit of mass equal to 0.001 kilogram (it weighs 0.035 ounce).
- gynecologic Having to do with the female reproductive tract (including the cervix, endometrium, fallopian tubes, ovaries, uterus, and vagina).
- health care provider A person who supplies health care services. Health care providers include individuals with professional training (including doctors, nurses, technicians, and aides).
- heart attack The blockage of an artery supplying blood and oxygen to the heart, resulting in the damage or death of a section of heart muscle.
- heart failure A condition in which the heart is unable to pump the amount of blood needed by the body. It is caused by high blood pressure, heart attack, and other disorders of the heart or blood vessels. Also called congestive heart failure.
- heart palpitation Forceful and irregular beating of the heart.
- heart rhythm The regular beating of the heart as it moves blood throughout the body.
- hemochromatosis A condition in which the body absorbs more iron than it needs and stores it in the liver, heart, and pancreas. Hemochromatosis causes liver disease, heart problems, and organ failure.
- hemodialysis The use of a machine to remove wastes and extra fluid from the blood when the kidneys have stopped working. The cleaned blood is then returned to the body.
- hemoglobin The substance inside red blood cells that carries oxygen from the lungs to the body's tissues.
- hepatitis A group of diseases in which the liver becomes enlarged and inflamed, causing fever, nausea, vomiting, abdominal pain, and dark urine.
- herb A plant used in cooking, in tea, and for medicinal purposes.
- herbal Having to do with or made from medicinal or edible plants.
- hives Raised red bumps or patches on the surface of the skin that come and go and itch, burn, or sting. They are usually caused by an allergic reaction to drugs, food, or insect bites. Also called urticaria.
- home birth Having a baby in the home rather than at a birthing center or hospital.
- home remedy A traditional treatment that uses certain foods or common substances that may have medicinal properties or cause a placebo effect. Examples include chicken soup (for colds and flu), certain teas (for headache, fever, or stomach ache), and duct tape (for broken bones and plantar warts).
- homocysteine An amino acid (a building block of protein). At high blood levels, it may increase the risk of developing coronary heart disease, heart attack, stroke, and Alzheimer's disease. Elevated homocysteine may also increase the risk of developing osteoporosis and bone fractures.
- hormone replacement therapy HRT. Hormones (estrogen, progesterone, or both) given to women after menopause to make up for the hormones no longer made by the ovaries. Also called hormone therapy.
- hormone A group of chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be manufactured.
- hot flash A sudden, temporary onset of body warmth, flushing, and sweating (often associated with menopause).
- hydrochloric acid An acid made in the stomach. It works with enzymes (substances that speed up chemical reactions in the body) to break down proteins during digestion.
- hyperthyroidism A condition in which your thyroid gland makes more hormone than your body needs. Symptoms include weight loss, fatigue, restlessness, frequent bowel movements or diarrhea, and goiter.
- hypervitaminosis A Abnormally high amounts of vitamin A stored in the body. It can cause headache, blurred vision, nausea, vomiting, dizziness, and birth defects. Also called vitamin A toxicity.
- hypothyroidism A disorder in which the thyroid gland makes too little hormone for the body to function well. Thyroid hormones affect chemical reactions in the body, brain development, breathing, heart and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, cholesterol levels, and body weight.
- hysterectomy Surgery to remove the uterus. A partial hysterectomy is removal of the uterus only. A total hysterectomy is removal of the uterus and part or all of the cervix.
- immune function Substances made and action taken by cells that fight disease and infection.
- immune system A group of organs and cells that defends the body against infection, disease, and altered (mutated) cells. It includes the thymus, spleen, lymphatic system (lymph nodes and lymph vessels), bone marrow, tonsils, and white blood cells.
- immunity The condition of being protected against or resistant to an infectious disease.
- immunization A method used to cause an immune response that helps protect against a specific disease, especially an infectious one. An example is the injection given to prevent chicken pox.
- impotence In medicine, the inability to get or keep an erection firm enough for sexual intercourse. Also called erectile dysfunction.
- in vitro In the laboratory (outside the body).
- in vivo In the body.
- inactive ingredient A substance that has no medicinal effect on the body. Uses of small amounts of inactive ingredients in dietary supplements include holding the tablet together, improving the taste or smell, and increasing the stability of the key ingredient.
- incidence The number of new cases of a disease diagnosed in a specific group of people during a specific period of time. For example, the annual incidence of childhood cancer is 14.6 cases per 100,000 children aged birth to 14 years.
- infant formula An artificial form of breast milk.
- infant A child younger than 12 months old.
- infection The invasion and spread of germs in the body. The germs may be bacteria, viruses, yeast, or fungi.
- infertility The inability to produce children.
- inflammation Redness, swelling, pain, and/or a feeling of heat in an area of the body. It is a protective reaction to injury, disease, or irritation of tissues.
- inflammatory bowel disease IBD. Long-lasting (chronic) problems that cause irritation and ulcers in the digestive tract. The most common disorders are ulcerative colitis and Crohn's disease.
- ingestion Taking into the body by mouth.
- inherit In genetics, to receive genes that are passed from parents to their children.
- inhibitory neurotransmitter A chemical that stops one nerve cell (neuron) from communicating with the next nerve cell, and decreases or blocks the transmission of nerve impulses. The main inhibitory neurotransmitter in the brain is gamma aminobutyric acid (GABA). See: excitatory neurotransmitter.
- injection Use of a syringe and needle to push fluids or drugs into the body. Also called a shot.
- inorganic Describes a substance that is not of plant or animal origin. For example, minerals are inorganic.
- insomnia Difficulty in going to sleep or in getting enough sleep.
- interaction A change in the way a dietary supplement acts in the body when taken with certain other supplements, medicines, or foods, or when taken with certain medical conditions. Interactions may cause the dietary supplement to be more or less effective, or cause effects on the body that are not expected.
- intervention Action taken to improve health or to treat or cure a disease.
- intestine The section of the digestive tract below the stomach, including the small and large intestines, rectum, and anus.
- intravenous Into or within a vein, such as an intravenous injection.
- intrinsic factor A protein made by the stomach that is needed to absorb vitamin B12 in the large intestine.
- investigation Observation, study, and examination.
- iodine A mineral the body needs to make thyroid hormones, which control metabolism (the process of turning the food you eat into energy your body can use) and many other essential functions, including bone and brain development during pregnancy and infancy. Iodine is found in seaweed, seafood, dairy products, grain products, eggs, and iodized salt.
- iodize To add iodine. For example, iodized table salt has a small amount of iodine added to it to help prevent iodine deficiency.
- ionizing radiation A type of radiation made (or given off) by x-ray procedures, radioactive substances, rays that enter the earth's atmosphere from outer space, and other sources. At high doses ionizing radiation increases chemical activity inside cells and can lead to health risks, including cancer.
- iridoid A category of compounds found in some plants.
- iron In nutrition, a mineral the body needs to make red blood cells, proteins, and enzymes; and for the control of cell growth and cell specialization. Iron is found in some foods, including red meats, fish, poultry, lentils, and beans.
- isoferulic acid A component of black cohosh.
- isoflavones Substances that naturally occur in some plants, especially soybeans. Isoflavones are a type of phytoestrogen and are similar to the hormone estrogen in people.
- isopropanol A substance used to kill germs and as a solvent to dissolve other substances into a solution. Also called isopropyl alcohol and rubbing alcohol.
- isopropyl alcohol A substance used to kill germs and as a solvent. Also called isopropanol and rubbing alcohol.
- isotretinoin A form of vitamin A used as a drug (such as Accutane) to treat acne and psoriasis. It is being studied in the prevention of some types of cancer. It can cause birth defects and may interfere with the ability of the liver to function properly. Also called 13-cis retinoic acid.
- kava The root of this plant has been used in traditional medicine to relieve stress, anxiety, tension, sleeplessness, and problems of menopause. The US Food and Drug Administration advises users that products containing kava may cause severe liver damage. Also called kava kava, intoxicating pepper, rauschpfeffer, tonga, and yangona. Latin name: Piper methysticum.
- kidney disease A condition that lessens the ability of the kidneys to filter wastes from the blood, keep blood chemical levels balanced, and make certain hormones. The two most common causes of kidney disease are diabetes and high blood pressure. People with long-term kidney disease may need dialysis or a kidney transplant to stay alive.
- kidney stone A “pebble” that forms in a kidney from salts and minerals in the urine. A small kidney stone is able to pass out of the body; a large stone may block the urinary tract and require medical help.
- kidney One of two organs that remove waste from the blood (as urine). The kidneys also make erythropoietin (a substance that stimulates red blood cell production) and help regulate blood pressure. The kidneys are located near the back under the lower ribs.
- labor The process of childbirth.
- laboratory study Research done in a laboratory. A laboratory study may use cells in test tubes or animals to find out if a drug, procedure, or other treatment is likely to be safe and useful. Laboratory studies usually take place before any testing is done in humans.
- laboratory test A medical procedure that involves testing a sample of blood, urine, tissue, or other substance collected from the body. Tests can help determine a diagnosis, plan treatment, check to see whether treatment is working, or monitor a disease over time.
- lactation The processes of making milk in the breast for feeding an infant.
- lactose A type of sugar found in milk and milk products.
- laxative A substance that moves the bowels and relieves constipation.
- legume Dried beans and peas, including kidney beans, pinto beans, black beans, navy beans, lima beans, black-eyed peas, garbanzo beans (chickpeas), split peas, and lentils. Legumes are good sources of protein, iron, zinc, dietary fiber, folate, and potassium.
- lens The clear part of the eye behind the iris that changes shape to focus near and far objects onto the retina (the nerve tissue at the back of the eye that receives images and sends them to the brain).
- liver A large organ located in the right upper abdomen. It stores nutrients that come from food, makes chemicals needed by the body, and breaks down some medicines and harmful substances so they can be removed from the body.
- loop diuretic Medication that is used to treat fluid build-up in the body and congestive heart failure. It may also be used to treat high blood pressure. Loop diuretics increase the amount of water that the body loses as urine.
- lot A batch, or a specific identified portion of a batch, having uniform character and quality within specified limits; or, an amount produced in a unit of time or quantity.
- low birth weight A baby weighing less than 5.5 pounds at birth. Low birth weight babies are at risk of sudden infant death syndrome (SIDS), infections, delayed development (for example, sitting, crawling, and talking), learning disabilities, and other health conditions, such as breathing problems, cerebral palsy, and heart disorders.
- lozenge A small, hard candy containing medicine that is dissolved in the mouth.
- lung An organ in the chest that supplies oxygen to the body and removes carbon dioxide. There are two lungs in the body.
- lutein A substance found in egg yolk and colorful fruits and vegetables such as spinach, kale, collard greens, broccoli, peas, brussels sprouts, kiwi, and red seedless grapes. Lutein is a carotenoid the body cannot use to make vitamin A. It is being studied in the prevention of certain eye diseases (age-related macular degeneration and cataracts).
- luteinizing hormone LH. A hormone made in the brain that is important for the release of an egg from an ovary during the menstrual cycle and in making the hormones testosterone and estrogen.
- lycopene A substance found in tomato products. Lycopene is also found in some colorful fruits and vegetables such as watermelon, guava, papaya, apricots, pink grapefruit, and blood oranges. Lycopene is a carotenoid the body cannot use to make vitamin A. It is being studied in the prevention of some types of cancer.
- lymphocyte A type of white blood cell that is part of the immune system. It defends the body against infection, disease, and altered (mutated) cells.
- lymphoma Cancer that develops in cells of your immune system, called lymphocytes. Lymphocytes are a type of white blood cell.
- macronutrients The carbohydrates, proteins, and fats in food that give you energy and maintain your body.
- macrophage A type of white blood cell that surrounds and kills microorganisms, removes dead cells, and stimulates the action of other immune system cells.
- malabsorption A reduced ability to properly absorb nutrients. It can be caused by injury to the digestive tract, a genetic disease, or other conditions. Malabsorption can lead to malnutrition.
- malaise General discomfort that may be an early symptom of illness.
- malaria A serious, sometimes fatal disease that is caused by a parasite and spread by infected mosquitoes. It causes fatigue, high fever, sweating, shaking chills, and anemia. Malaria is common in parts of Asia, Africa, Central and South America, the Pacific islands, and areas of the Caribbean.
- malformation A defect in the physical shape or structure of an organ or body part, caused by abnormal development before birth. Examples include spina bifida (in which part of the spinal cord is on the outside of the body) and cleft palate (an opening in the roof of the mouth). Also called a deformity.
- malnourished Describes a condition caused by not getting enough calories or the right amount of key nutrients needed for health. Key nutrients include vitamins and minerals.
- malnutrition A disorder caused by a diet that does not provide enough nutrition, an unbalanced diet, a digestive system that does not work properly, or a problem with absorbing or using nutrients.
- mast cell A type of white blood cell.
- mechanism of action The means by which a substance (such as a dietary supplement) is able to produce an effect in the body.
- medical history Information about a person’s health, such as allergies, illnesses, surgeries, medications, immunizations, and the results of tests and physical exams. It may also include information about health habits, such as diet and exercise, and health information about current and past illnesses of one’s parents and other close family members.
- medicinal Having to do with the abilities of medicine to prevent and cure.
- megaloblastic anemia A disorder in which red blood cells are larger than normal, immature, and few in number, which reduces the amount of oxygen that can be carried by the blood to the body's tissues. It is caused by a deficiency in folate or vitamin B12.
- menopause The time of life when a woman's menstrual periods stop. A woman is in menopause when she hasn't had a period for 12 months in a row. Also called "change of life."
- menstruation Periodic discharge of blood and tissue from the uterus. From puberty until menopause, menstruation normally occurs about every 28 days, except when a woman is pregnant.
- meta-analysis A methodical review of the results of multiple research studies. In a meta-analysis, statistical methods are used to measure the combined results of these studies and estimate an overall effect.
- metabolic Having to do with metabolism (all chemical changes that take place in a cell or organism to produce energy and basic materials needed for important life processes).
- metabolism All chemical changes that take place in a cell or an organism. These changes produce energy and basic materials needed for important life processes.
- metabolize To go through the process of metabolism (chemical changes that take place in a cell or an organism to produce energy and basic materials needed for important life processes).
- microgram µg or mcg. A unit of weight in the metric system equal to one millionth of a gram. (A gram is approximately one-thirtieth of an ounce.)
- micronutrients The vitamins and minerals in your diet that your body needs in small amounts.
- microorganism A living being that can be seen only through a microscope. Microorganisms include helpful and harmful bacteria, protozoa, algae, and fungi. Although viruses are not considered living organisms, they are sometimes classified as microorganisms.
- microscopic Too small to be seen without a microscope.
- migraine A type of headache that causes intense throbbing or pulsing pain, sensitivity to light and sound, and nausea and vomiting. A migraine often begins with visions of flashing lights, zigzag lines, and/or temporary loss of sight.
- milligram mg. A measure of weight. It is a metric unit of mass equal to 0.001 gram (it weighs 28,000 times less than an ounce).
- mineral In nutrition, an inorganic substance found in the earth that is required to maintain health.
- miscarriage The natural loss of a fetus before 20 weeks of pregnancy. Also called spontaneous abortion.
- mitigate To make milder or less painful.
- mortality The rate of death.
- mucous membrane The moist tissue that lines some organs and body cavities (such as the nose, mouth, and lungs) and makes mucus (a thick, slippery fluid). Also called mucosa.
- multivitamin/mineral dietary supplement MVM. A product that is meant to supplement the diet. MVMs contain a variety of vitamins and minerals. The number and amounts of these nutrients can vary substantially by product.
- multivitamin A product that is meant to supplement the diet. Multivitamins contain a variety of vitamins. The number and amounts of these nutrients can vary substantially by product.
- nasal Having to do with the nose.
- naturalize To introduce a plant from one geographic region to another, and to allow it to establish itself without cultivation, and grow as if it were native to the area.
- nausea The uneasy feeling of having an urge to throw up (vomit).
- neonate An infant during the first month of life after birth.
- neonatologist A doctor who specializes in diagnosing and treating diseases of newborn infants.
- nerve ending The end of a nerve fiber that projects from the cell body of a nerve cell (neuron).
- nerve A bundle of microscopic fibers that carries messages back and forth from the brain to other parts of the body.
- nervous system The brain and spinal cord, including the network of nerves that carry messages back and forth between the brain and all parts of the body. The nervous system controls what the body does.
- neurologic Having to do with nerves and the nervous system.
- neuron A nerve cell. Neurons send chemical and electrical messages throughout the nervous system that direct the body to function, move, think, and have emotions.
- neurotransmitter A chemical messenger that is made and used by nerve cells (neurons) to communicate with one another.
- neutrophil A type of white blood cell.
- nitrite A chemical substance that contains nitrogen and oxygen and is used to preserve food.
- nitrosamine A chemical substance that can form in the acid conditions of the stomach. It may cause cancer.
- nonorganic insomnia A sleep disorder (difficulty in going to sleep or getting enough sleep) that occurs as a symptom of a physical or mental disease.
- norethisterone acetate A substance used in oral contraceptives (birth control pills) and as a treatment for endometriosis (a condition in which tissue that is normally found inside the uterus grows elsewhere in the abdomen).
- nursing Breastfeeding.
- nutrient content claim A statement on a food or dietary supplement product label that describes the amount of a nutrient or dietary substance in a product. Examples of nutrient claims for dietary supplement products include fortified, high, rich in, excellent source of, good source of, and high potency.
- nutrient A chemical compound in food that is used by the body to function and maintain health. Examples of nutrients include proteins, fats, carbohydrates, vitamins, and minerals.
- nutrition The process of eating, digesting, and absorbing nutrients (such as protein, carbohydrate, fat, vitamins, minerals, and water) from food to maintain the body, grow new cells, repair tissues, and supply energy. Nutrition is also the science of food, diet, and health.
- nutritional yeast A food product or food additive made from yeast (a fungus). The yeast is pasteurized (heated) to prevent it from growing in a person's digestive tract. Nutritional yeast is used as a source of protein and B vitamins. Some (but not all) brands of nutritional yeast contain vitamin B12. Latin name: Saccharomyces cerevisiae.
- nutritional Having to do with nutrition (eating, digesting, and absorbing the nutrients in food, and the health and disease consequences).
- objective Having to do with fact, experience, or direct observation rather than personal opinion or feeling.
- observational study A type of research in which individuals are observed for a specific period of time, sometimes for many years, and certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given).
- oleic acid A fatty acid found in animal fats and vegetable oils.
- omega-3 fatty acid A main component of fats used by the body for energy and tissue growth. Omega-3s are essential fatty acids in the human diet; they are found in fish oil and certain plant and nut oils.
- oral By mouth; having to do with the mouth.
- organism A living thing such as an animal, a plant, a bacterium, or a fungus.
- osteoarthritis A disease that breaks down the cartilage in your joints. Over time, the cartilage wears away, your bones rub together, and you can have joint pain, stiffness, and swelling, typically in your fingers, thumbs, knees, hips, neck, and lower back.
- osteoporosis A condition in which bones become weak and brittle, increasing the chance they may break.
- outcome A specific endpoint measured in a clinical trial. Examples include weight loss, cholesterol levels, severe toxicity, worsening of disease, and death.
- ovariectomize To remove one or both ovaries (the female reproductive organs in which eggs are made and stored).
- ovary One of a pair of female reproductive glands in which the eggs (ova) are formed and stored. The ovaries are located in the pelvis, one on each side of the uterus.
- oxazepam A drug used to treat anxiety, sleeping disorders, irritable bowel syndrome, and the symptoms of alcohol withdrawal. It belongs to the family of drugs called benzodiazepines.
- oxidation In chemistry, the addition of oxygen atoms to a chemical substance or the loss of electrons by a chemical substance.
- oxidative damage Changes that take place in the body¹s cells as a normal result of living (such as from eating food or being exposed to sunlight). Too many of these chemical changes may increase the risk of chronic diseases like cancer, heart disease, diabetes, and age-related eye disease. Antioxidants help to protect the body from excess oxidative damage.
- palpitation A fluttering sensation in the chest, usually caused by a forceful or irregular heart beat.
- pancreas An organ in the abdomen. It makes a liquid (called pancreatic juice) containing enzymes that aid in digestion, and makes several hormones, including insulin. The pancreas is surrounded by the stomach and intestines.
- pancreatic cancer Uncontrolled growth of abnormal cells in the pancreas, an organ behind the stomach that makes pancreatic juices to help digest food, and several hormones, including insulin.
- pantothenic acid A nutrient that is needed by the body to make energy from food and to make red blood cells, certain hormones, and the fats found in cell membranes and in tissue surrounding nerves. Pantothenic acid is found in some foods, including meat, fish, eggs, milk products, legumes, whole grains, yeast, and vegetables.
- parenteral Having to do with providing substances for the body without using the gastrointestinal tract. Examples include an intravenous infusion, an injection under the skin, or an injection into a muscle.
- participant withdrawal When a person enrolled as a subject in a clinical trial stops participating before the study is completed.
- pediatrician A medical doctor (physician) who specializes in the treatment of children.
- peer-reviewed journal A scholarly or scientific publication in which an article is reviewed by a board of experts before it is published. The board members determine the accuracy of the article and approve or reject it.
- peppermint A plant that has been used in traditional medicine in many parts of the world to relieve indigestion, cough, sore throat, headache, abdominal cramping, and gas. Also called brandy mint, lamb mint, and lammint. Latin name: Mentha piperita.
- percentile A ranking on a scale of 100 that indicates the percent of others at or below that score. For example, a child with a weight in the 95th percentile for her age is heavier than 95 percent of all children her age; 5 percent of children her age weigh more.
- perimenopausal The time of life near menopause when a woman's menstrual periods become irregular.
- peripheral artery disease A disorder in which the arteries supplying blood to the kidneys, stomach, arms, legs, or feet become blocked by a build-up of fat and cholesterol deposits inside the arteries (atherosclerosis), causing cramping and weakness.
- peristalsis A wavelike movement of muscles that moves food and liquid through the gastrointestinal tract.
- pharmacist A person licensed to make and dispense (give out) prescription drugs and who has been taught how they work, how to use them, and their side effects.
- phytochemicals A general term for the many substances that are naturally produced by plants (“phyto” means plant). Colorful fruits and vegetables, whole grains, legumes, herbs, nuts, and seeds are rich in phytochemicals. Types of phytochemicals include anthocyanins, carotenoids, flavonoids, isoflavones, and polyphenols. Also called phytonutrients.
- phytoestrogen A weak estrogen-like substance found in some plants and plant products. Isoflavones, a type of phytoestrogen, are being studied in the prevention of osteoporosis, menopausal symptoms, and some types of cancer. Soybeans are a rich source of phytoestrogens.
- phytomedicine The use of herbs and other plants for their therapeutic or medicinal qualities. Also called phytotherapy.
- pica An eating disorder in which a person eats things that are not food, such as dirt, clay, paint flakes, sand, hair, or paper. Pica is more common in young children and in people with brain injuries or developmental disabilities.
- pinkeye An infection or inflammation of the lining of the eyelid and the white part of the eye. Also called conjunctivitis.
- placebo An inactive substance or treatment that has no effect on the body and that ideally looks, smells, and tastes the same as, and is given the same way as, the active drug or treatment being tested. The effects of the active substance or treatment are compared to the effects of the placebo.
- placenta The organ that delivers nutrients and oxygen and takes away carbon dioxide and other metabolic wastes from the developing fetus in the uterus.
- plasma The yellowish fluid part of blood in which blood cells are found. The plasma contains proteins that form blood clots.
- platelet Fragments of bone marrow cells (megakaryocytes) that help prevent bleeding by causing blood clots to form. Also called a thrombocyte.
- polyphenols Substances that occur naturally in plants. More than 8,000 polyphenols are found in plant foods, including berries, black grapes, cherries, coffee, dark chocolate, and red onions.
- polysomnography PSG. The use of an instrument (called a polysomnograph) that is used to measure the quality of sleep and identify sleep disorders. PSG records measurements of brain activity, eye movement, and muscle tension in the face, and may include the measurement of heart rate, breathing rate, leg movements, blood pressure, and body temperature.
- population All individuals who share something in common (such as geographic location, ethnicity, gender, age, or disease). In statistics, conclusions are made about the population by studying smaller sample groups of individuals who are representative of the larger group.
- porous Full of holes.
- postmenopausal Having to do with the time after menopause. The time in a woman's life when menstrual periods stop permanently is called menopause ("change of life").
- postterm baby A baby born after the normal 42 weeks of pregnancy.
- potassium A mineral that helps the body’s nerves to function, muscles to move, and heart to beat. Potassium helps balance some of the harmful effects of salt on blood pressure.
- poultry Birds that are raised for eggs or meat, including chickens, turkeys, ducks, and geese.
- premature infant A baby born before 37 weeks of pregnancy. Normally pregnancy lasts 42 weeks. Also called preterm infant and preemie.
- premenstrual syndrome (PMS) Severe symptoms that occur 1 or 2 weeks before menstruation, including cramping, bloating, and tender breasts; food cravings; mood swings and irritability; and headache and fatigue.
- prenatal Before birth; during pregnancy.
- preparation A mixture made for medicinal use.
- prescription A written order from a health care provider for medicine, therapy, or tests.
- prevalence In medicine, the percentage of a population that is affected with a specific disease at any one time.
- prevent To stop from happening.
- prevention In medicine, action taken to decrease the chance (risk) of developing a disease.
- progestin A natural or laboratory-made substance that has some or all of the biologic effects of progesterone, a female hormone.
- progression In medicine, the course of a disease as it becomes worse. For example, as cancer progresses, it spreads in the body.
- prolactin A hormone made by the pituitary gland (an organ located at the base of the brain) and important for making breast milk and in ovulation (the release of an egg from an ovary during the menstrual cycle).
- proliferation Multiplying or increasing in number. In biology, cell proliferation occurs by a process called cell division.
- proprietary A product or technique that is developed and owned by a company or individual, cannot be used by others without approval, and may be protected by patent or copyright.
- prostate cancer Uncontrolled growth of abnormal cells in the prostate (a gland in the male reproductive system found below the bladder and in front of the rectum). Prostate cancer usually occurs in older men.
- protein-energy malnutrition A group of conditions that result when the body does not get enough protein or energy (calories), or both, to support growth and development and for the body to work properly.
- protein A molecule made up of amino acids that the body needs for good health. Proteins are the basis of body structures such as skin and muscle, and substances such as enzymes and antibodies.
- proton pump inhibitor PPI. A drug that reduces the amount of acid made by the stomach. It is used to treat peptic ulcer and gastroesophageal reflux disease.
- provitamin A substance found in some foods that the body can use to make a vitamin. An example of a provitamin is beta-carotene, which the body uses to make vitamin A. Also called a vitamin precursor.
- prudent Wise; using good judgment.
- pruritus An itching sensation that triggers the desire to scratch. Pruritus can range from mild to severe.
- psoriasis A chronic inflammatory disease in which the skin becomes swollen, red, and itchy, with patches of silvery-white scales.
- pyridoxine A form of vitamin B6.
- quality control A system to ensure that consistency and uniformity are maintained in the manufacturing of a product.
- quality of life The overall enjoyment of life, a sense of well-being, and the ability to carry out routine activities.
- radiation therapy The use of high-energy radiation from x-rays and other sources to kill cancer cells, shrink tumors, and treat other conditions.
- randomization When referring to an experiment or clinical trial, the process by which animal or human subjects are assigned by chance to separate groups that compare different treatments or other therapies. Randomization gives each participant an equal chance of being assigned to any of the groups.
- red blood cell A cell that carries oxygen to and removes carbon dioxide from all parts of the body.
- regimen A treatment plan that specifies the dosage, schedule, and duration of treatment.
- regulate To govern, make uniform, and bring under the control of a rule, principle, or legal system. In the United States, the FDA has the authority to regulate dietary supplements.
- remission A decrease in or disappearance of signs and symptoms of disease.
- reproductive age The time of life during which a person is able to conceive a child. It begins in puberty (for men and women) and ends after menopoause (for women only).
- reproductive organ A sex organ. In females, reproductive organs include the ovaries, fallopian tubes, uterus, cervix, and vagina. In males, reproductive organs include the prostate, testes, and penis.
- resin A substance found in some plants.
- respiratory tract The organs that are involved in breathing. These include the mouth, nose, throat (pharynx), voicebox (larynx), windpipe (trachea), air passages between the windpipe and lungs (bronchial tubes), and lungs. Also called the respiratory system.
- respiratory Having to do with breathing. The organs that are involved with breathing include the mouth, nose, throat (pharynx), voicebox (larynx), windpipe (trachea), air passages between the windpipe and lungs (bronchial tubes), and lungs.
- restless leg syndrome A disorder of the nervous system that causes unpleasant or painful feelings in the legs, especially when relaxing, which results in uncontrollable urges to move them.
- retina The light-sensitive layers of nerve tissue at the back of the eye that receive images and send them as electric signals through the optic nerve to the brain.
- retinal The form of vitamin A needed for proper vision. It is made by the body from beta-carotene. Also called retinaldehyde.
- retinitis pigmentosa A group of inherited eye diseases that affect the retina (the light-sensitive part of the eye), causing a gradual loss of night vision and peripheral vision and usually resulting in partial blindness.
- retinoid A category of vitamin A compounds. The retinoids include retinol, retinal, and retinoic acid. Synthetic retinoids are manufactured for use in treating acne, psoriasis, and other skin disorders.
- retinol binding protein RBP. A molecule that binds to retinol (the form of vitamin A in foods that come from animals) and carries it through the blood to tissues where it is used, and to the liver where it is stored.
- retinol A form of vitamin A found only in foods that come from animals. The body can use retinol to make retinal and retinoic acid (other forms of vitamin A). Retinol is found in some foods, including beef liver, whole eggs, whole milk, margarine, and some fortified food products such as breakfast cereals. Retinol is a retinoid. Also called preformed vitamin A.
- retinyl ester A form in which newly absorbed retinol (the form of vitamin A in foods that come from animals) is stored in the body.
- retinyl palmitate The main form in which retinol (the form of vitamin A in foods that come from animals) is stored in the body.
- rheumatism A group of disorders characterized by inflammation or pain in the body's connective tissues (bone and cartilage).
- rheumatoid arthritis An autoimmune disease that causes pain, swelling, and stiffness in the joints. It may cause severe joint damage, loss of function, and disability. The disease may last from months to a lifetime, and symptoms may improve and worsen over time.
- rhizome A horizontal stem that grows shallowly underground. At nodes along the rhizome, below-ground roots and above-ground shoots grow into new plants. Examples include strawberries and many types of grasses.
- ribonucleic acid RNA. A substance that tells cells how to make proteins.
- rickets A condition in children in which bones become soft and deformed because they don’t have enough calcium and phosphorus. It is caused by not having enough vitamin D in the diet or by not getting enough sunlight. In adults, this condition is called osteomalacia.
- rigorous Accurate, precise, and without deviation from standards.
- risk factor Something that may increase the chance of developing a disease. For example, a diet that is low in calcium and vitamin D is a risk factor for osteoporosis; smoking is a risk factor for lung cancer.
- risk The chance or probability that a harmful event will occur. In health, for example, the chance that someone will develop a disease or condition.
- root A part of a plant that is below ground.
- safety data Information about unwanted symptoms or diseases related to the use of drugs, medical devices, dietary supplements, food, and cosmetics.
- sample A subset of individuals selected from a larger population. A sample is used to form conclusions about the general population.
- saponin A substance found in some plants. Saponins may help lower cholesterol and may have anticancer effects.
- sarcoidosis A disease in which tiny lumps (granulomas) form in cells on the inside or outside of the body. It often starts in the lungs or lymph nodes, but can occur in the skin, eyes, liver, or any organ. There may be no symptoms, or it can cause shortness of breath, fatigue, rash, pain, or death.
- scale A standardized tool used to measure or rate. For example, specific scales are used to measure a person's quality of life and the severity of pain.
- scientific literature Published peer-reviewed original research in the sciences and social sciences.
- scientific study A method of gaining knowledge by making observations, proposing educated guesses (hypotheses) to explain the observations, and testing the hypotheses in ways that have reproducible results.
- screening Checking for a disease or condition when there are no symptoms.
- scurvy A disease caused by a lack of vitamin C in the diet. Symptoms include anemia, gum disease, bleeding, and bruising.
- secondhand smoke Smoke that comes from the burning end of a cigarette, cigar, or pipe and smoke exhaled by a smoker. Inhaling secondhand smoke can cause cancer, respiratory tract infections, and heart disease.
- sedative A drug or other substance that helps cause relaxation, calmness, and sleepiness.
- seizure Sudden changes in behavior caused by excessive electrical activity in the brain.
- selenium A mineral required in very small amounts to make important enzymes that are essential for good health. Selenium is found in some foods, including plant foods grown in selenium-rich soil, and some meats and seafood.
- senna A plant used in traditional Chinese medicine and Ayurvedic medicine. The leaves are used to make a stimulant laxative that increases the frequency of bowel movements and relieves constipation. It is widely used in over-the-counter laxatives. Latin name: Senna alexandrina.
- sennoside The active ingredient in senna, a plant whose leaves are used to make a stimulant laxative that increases the frequency of bowel movements and relieves constipation.
- sesquiterpene A substance found in some plants.
- sewage sludge The material that results from processing human waste at sewage treatment facilities.
- sex hormone binding globulin SHBG. A protein made by the liver that carries a male hormone (testosterone) and a female hormone (estradiol, a form of estrogen) through the blood to body tissues. Estrogen causes levels of SHBG to increase; testosterone causes levels of SHBG to decrease.
- short bowel syndrome A condition in which people cannot absorb enough water, vitamins, minerals, protein, fat, calories, and other nutrients from the food they eat because their small intestine is too short. The intestine is too short because they have undergone surgery to remove a portion of it, it is damaged, or they were born without one.
- short-chain fatty acid A fat molecule that is composed of 6 or fewer carbon atoms. This type of fat is able to dissolve in water and is digested and absorbed more rapidly than other fats.
- sickle cell disease An inherited disease in which the body makes abnormal red blood cells that carry less oxygen from the lungs to the rest of the body. These abnormal red blood cells form clumps that get stuck in the blood vessels, causing pain, infections, and organ damage.
- sign An indication of disease that can be seen and/or measured. Examples include high fever, high blood pressure, infection, and coughing up blood.
- skin cancer Cancer that forms in tissues of the skin. Most skin cancers form in older people on parts of the body exposed to the sun or in people who have weakened immune systems.
- sleep disorder A consistent disruption of the normal pattern of sleep.
- sleep latency The period of time between settling down to go to sleep and actually falling asleep.
- slow-wave sleep Deep, nondreaming sleep.
- small intestine The part of the digestive tract that is located between the stomach and the large intestine.
- solution A liquid in which another substance has been dissolved or mixed.
- soy A plant that produces beans used in many food products. Soy products contain isoflavones (estrogen-like substances) that are being studied in the prevention of cancer, hot flashes that occur with menopause, and osteoporosis (loss of bone density). Also called soya and soybean. Latin name: Glycine max.
- spasm An abnormal and uncontrollable muscle contraction or cramp.
- species The name of a category that is part of the scientific classification of all organisms. The category species is located in the classification system after kingdom, phylum, class, order, family and genus. Humans, for example, belong to the genus Homo and the species Homo sapiens.
- specimen In medicine, a small amount of tissue or fluid from the body used for analysis, such as a blood sample.
- spina bifida A disorder in which a fetus's spine does not close properly during the first month of pregnancy. It may result in permanent damage to the nerves and spinal cord, causing paralysis of the legs and feet, bowel and bladder problems, learning problems, or hydrocephalus (too much fluid on the brain).
- spleen A fist-size organ under your ribs and above your stomach on the left side of your body. Your spleen filters your blood and breaks down old red blood cells, stores blood for emergencies such as trauma, and helps your body fight infection by making white blood cells that destroy bacteria, viruses, and other germs.
- standard reference material An authenticated material.
- standard treatment Medical therapy that is widely accepted and used by most health care professionals as an appropriate treatment for a particular condition.
- statin A drug used to treat high cholesterol. Statins lower the amount of cholesterol and certain fats in the blood.
- statistical difference A mathematical measure of variation between groups that is greater than what might be expected to happen by chance alone.
- statistical effect Describes a mathematical measure of difference between groups.
- statistically significant In medicine, a mathematical measure of difference between two or more groups receiving different treatments that is greater than what might be expected to happen by chance alone.
- status The state or condition. For example, a person’s vitamin B12 status is measured by doing a laboratory test on a blood sample.
- stimulant A substance that increases brain activity, alertness, attention, blood pressure, heart rate, breathing, and energy.
- stolon A specialized stem that grows horizontally on top of the ground; roots and new plants form at nodes along the stolon. An example is the strawberry plant.
- stool The waste matter passed in a bowel movement; feces.
- study design A plan for collecting and using information to properly test an educated guess (hypothesis).
- stunted growth Not able to reach the expected height, size, or level of development for a child’s age.
- subclinical Having to do with the early stage of a disease, before signs and symptoms appear.
- subcutaneous Beneath the skin.
- subjective improvement An improvement that is reported by a person but cannot be measured by a healthcare provider. For example, "I feel better."
- subjective measurement A method of determining an effect when precise numbers cannot be known. Examples of tools used in subjective measurement include questionnaires and sliding scales. For example, "On a scale of 1 to 10, my pain is an 8."
- sunscreen A substance that helps protect the skin from the sun's harmful rays. Sunscreens reflect, absorb, and scatter ultraviolet A and ultraviolet B light to provide protection against both types of light. Using lotions, creams, or gels that contain sunscreens can help protect the skin from premature aging and damage that may lead to skin cancer.
- supplement A nutrient that may be added to the diet to increase the intake of that nutrient. Sometimes used to mean dietary supplement.
- symptom A feeling of sickness that an individual can sense, but that cannot be measured by a healthcare professional. Examples include headache, tiredness, stomach ache, depression, and pain.
- synaptic cleft The gap between nerve cells (neurons). Nerve cells communicate with each other by sending and receiving chemical messages (neurotransmitters) across the synaptic cleft.
- synaptosome A sac of nerve-ending particles that have been processed in a centrifuge in the laboratory. Synaptosomes are used in lab tests to study communication between nerve cells (neurons).
- synergism The interaction of two or more substances to produce an effect that is greater than what would be expected by adding the separate effects of each.
- synthesis Creating something new by putting together separate parts (such as, chemicals). For example, sunlight is needed for vitamin D synthesis in the skin.
- synthetic Made by combining parts to make a whole; usually having to do with substances that are artificial or manufactured.
- tamoxifen A drug used to treat breast cancer and to prevent cancer in women who have a high risk of developing breast cancer. Tamoxifen blocks the effects of the hormone estrogen in the breast. It belongs to the family of drugs called antiestrogens.
- tea A drink made by adding boiling water to fresh or dried herbs and steeping (soaking) them. It may be drunk either hot or cold. Also called an infusion.
- theoretical Describes an assumption that is supported by scientific evidence, but has not been proven.
- therapeutic effect The beneficial response or outcome of a treatment or prevention measure.
- therapeutic Used to treat disease and help healing take place.
- thiamin An important nutrient that is needed by the body to make energy from food, for cell and muscle function, and for a healthy nervous system. Thiamin is found in some foods, including enriched breads and cereals, legumes, liver, nuts, pork, and whole grains.
- tincture A liquid made by soaking an herb in a solution of alcohol and water. It is used for concentrating and preserving an herb and may be made in different strengths that are expressed as ratios of the weight of the dried herb to the volume or weight of the finished product.
- tolerance The ability to take a drug or dietary supplement without discomfort or unwanted side effects. Also, a condition that occurs when the body gets used to a drug or dietary supplement so that either larger amounts or a different drug or supplement is needed to get the same effect originally experienced.
- toxic Having to do with poison or something harmful to the body. Toxic substances usually cause unwanted health effects.
- toxicity The degree to which something is poisonous (toxic).
- tranquilizer A drug used to treat anxiety and insomnia. It belongs to the family of drugs called central nervous system (CNS) depressants. An example is valium.
- transplant The replacement of tissue with tissue from the person's own body or from another person.
- treat To care for a patient with a disease by using medicine, surgery, or other approaches.
- tremor A trembling or shaking in one or more parts of the body, usually the hands. An individual can also have tremors in the arms, head, face, vocal cords, torso, and legs.
- triglyceride A type of fat found in your blood. When you eat more than you need, your body turns the excess calories into triglycerides. High blood levels of triglycerides can increase your risk of heart disease, heart attack, and stroke.
- triterpene glycoside A family of chemicals found in some plants. Examples of triterpene glycosides are acetein, cimicifugoside, and 26-deoxyacetin, which are components of the herb black cohosh.
- triterpene A chemical compound found in some plants.
- valerian The roots of this plant are used by some cultures as an ingredient in mild sedatives and sleep aids for nervous tension and insomnia. It is being studied in improving sleep in patients undergoing treatment for cancer. Latin name: Valeriana officinalis.
- vegan A person who eats only plant-based foods. Vegans do not eat meat, poultry, fish, eggs, milk, dairy products, or honey, and do not use leather, silk, or wool, or soaps and cosmetics that are made from animal products.
- vegetarianism The practice of avoiding all or most animal products for environmental, philosophical, and health reasons. Vegetarians (people who practice vegetarianism) eat a diet based on foods that come from plants and may include some dairy products and eggs. See: vegetarian diet.
- vitamin E A nutrient needed by the body to help keep the immune system healthy and to repair damage to DNA. It is an antioxidant that protects cells from free radical damage. Vitamin E is found in some foods, including vegetable oils, nuts and seeds, fortified breakfast cereals, and spinach, broccoli, kiwi, and mangos.
- vitamin K A nutrient needed by the body to function and stay healthy. It helps form blood clots and maintain strong bones. Vitamin K is found in some foods, including green leafy vegetables, broccoli, liver, and vegetable oils. It is also made by bacteria that live in the large intestine.
- vitamin A nutrient that the body needs in small amounts to function and maintain health. Examples are vitamins A, C, and E.
- volatile oil An oil that vaporizes easily and is responsible for the fragrance of some plants.
- volatile Describes a substance that evaporates quickly.
- water soluble vitamin A vitamin that dissolves in water and is excreted in the urine. Foods that supply water-soluble vitamins need to be eaten regularly because they cannot be stored in the body. Water-soluble vitamins include vitamin C, biotin, folate, niacin, pantothenic acid, riboflavin (vitamin B2), thiamin, and vitamin B6.
- well-being The state of feeling healthy, happy, and content. Well-being is affected by things such as physical and mental health, income, education, social support, attitude, values, stress, security, and other qualities of life.
- zeaxanthin A substance found in corn, leafy green vegetables, persimmons, tangerines, seeds, and egg yolk. It is a carotenoid the body cannot use to make vitamin A. It is being studied in the prevention of certain eye diseases (age-related macular degeneration and cataracts).
- Bailey RL, Gahche JJ, Miller PE, Thomas PR, Dwyer JT. Why US adults use dietary supplements. JAMA Intern Med. 2013;173(5):355-361.
- National Institutes of Health Office of Dietary Supplements. Dietary supplements: what you need to know. https://ods.od.nih.gov/HealthInformation/DS_WhatYouNeedToKnow.aspx. Accessed July 7, 2021.
- National Institutes of Health Office of Dietary Supplements. (2021). Dietary Supplements: What You Need to Know. Retrieved from https://ods.od.nih.gov/factsheets/DietarySupplements-HealthProfessional/
- U.S. Food and Drug Administration. (2021). Dietary Supplements. Retrieved from https://www.fda.gov/food/dietary-supplements
- Mayo Clinic. (2021).
- Dietary supplements: Do they help or hurt? Retrieved from https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/dietary-supplements/art-20044894
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