Dietary Supplements

Dietary supplement refers to any product (besides tobacco) that contains a vitamin, a mineral, a medicinal herb, an amino acid, an enzyme, or a hormone and that is intended to supplement the normal diet. Dietary supplements are taken as capsules, tablets, or liquids. In the United States, the Food and Drug Administration (FDA) does not closely regulate dietary supplements. Thus, the claims that dietary supplements help maintain or restore health and are safe may or may not be true. Nutraceutical, a similar term, refers to any food or supplement that is thought to have a health benefit.

Medicinal herbs are one type of dietary supplement. They are derived from plants. Many herbs have been used to prevent disease and improve health for centuries. The herbs most commonly used by older people include ginkgo, garlic, and saw palmetto.

Some supplements contain hormones or enzymes that the body produces less of as it ages. People hope that such supplements will slow aging, increase energy, or prevent disorders that are common in old age. However, why the body produces less of these substances is not known. So replacing them may not be beneficial and may be harmful. No supplement has been shown to slow or reverse aging.

Acetyl-L Carnitine

Acetyl-L carnitine is a form of carnitine, an amino acid produced in the body. Carnitine is involved in heart function, brain function, the body's processing (metabolism) of fats, and energy production.

Medicinal claims: Acetyl-L carnitine supplements are used to increase energy and exercise performance, relieve chronic fatigue, prevent weight gain, improve heart or brain function, help persistent leg ulcers heal, and prevent aging. Acetyl-L carnitine has also been used to treat people who have dementia (including Alzheimer's disease), depression, or coronary artery disease.

At present, there is not enough evidence to determine whether this supplement is beneficial or harmful in treating older people with Alzheimer's disease. No evidence supports other claims. Acetyl-L carnitine supplements are approved to treat people with a deficiency in carnitine.

Possible problems: Acetyl-L carnitine may cause body odor, skin rashes, and digestive disturbances (such as nausea, vomiting, diarrhea, and abdominal cramps). People with chronic liver disease should not use this supplement.

Use of D-carnitine, another form of carnitine, can result in severe weakness and loss of muscle tissue. So checking the label of carnitine supplements is particularly important.

Chamomile

Chamomile is a perennial herb with a daisylike flower. The flower is dried and used as tea or in extracts.

Medicinal claims: Chamomile has been used to calm, relax, and help with sleep. Chamomile extract applied in a compress is used to soothe irritated skin. Various substances in chamomile reduce inflammation and fever. Chamomile is sometimes used to relieve stomach cramps and indigestion. It is also claimed to help gastric ulcers heal.

Studies in animals suggest that substances in chamomile inhibit the growth of the bacteria involved in stomach ulcers (Helicobacter pylori). However, no studies in people support the claim that it can prevent or treat ulcers.

Possible problems: Chamomile may interact with several drugs, iron supplements, and alcohol. Some people are allergic to the pollen in chamomile products. These people may have a severe allergic (anaphylactic) reaction if they take chamomile by mouth. If they apply chamomile to the skin, they may develop a skin rash.

Chondroitin

Chondroitin is a component of cartilage, bone, and blood vessels. As a supplement, it is derived from cow or shark cartilage or is made synthetically. It is often combined with glucosamine, which also occurs in cartilage.

Medicinal claims: Chondroitin supplements have been shown to relieve the pain of one type of arthritis, osteoarthritis. Whether chondroitin protects cartilage or prevents the progression of osteoarthritis is not clear.

Possible problems: Chondroitin supplements appear to be relatively safe. They may cause some mild digestive disturbances, such as abdominal pain and nausea. Supplements derived from cartilage may cause an allergic reaction. Chondroitin may interact with drugs taken to prevent blood clots (including anticoagulants and aspirin).

Coenzyme Q₁₀

Coenzyme Q₁₀ (ubiquinone) is a protein produced by the body. It is used to produce energy in cells. It also acts as an antioxidant. That is, it protects cells from free radicals. Free radicals, which are by-products of normal cell activity, can damage cells.

Medicinal claims: Coenzyme Q₁₀ is claimed to help the heart and immune system function better, to control diabetes, and to lower blood pressure. Coenzyme Q₁₀ is added to skin care products to minimize and prevent wrinkles.

A few studies suggest that coenzyme Q₁₀ is likely to benefit people with heart disorders, especially those with heart failure. However, in other studies, no benefit was seen. Some evidence suggests that coenzyme Q₁₀ protects the heart from the harmful effects of certain chemotherapy drugs used to treat cancer. Some advocates suggest that coenzyme Q₁₀ is useful in treating cancer because of its antioxidant effects. But the evidence supporting this claim is inconclusive.

Possible problems: Side effects include mild insomnia, rashes, an increase in levels of liver enzymes, and digestive disturbances (including loss of appetite, heartburn, nausea, and diarrhea). Coenzyme Q₁₀ may interact with the anticoagulant warfarin, drugs taken by mouth to treat diabetes (such as glyburide and tolazamide), and certain drugs used to lower cholesterol (statins, such as atorvastatin, fluvastatin, pravastatin, and simvastatin).

Creatine

Creatine is an amino acid made in the liver and stored in muscles. It is a readily available source of energy in the body. Certain foods, such as milk, steak, and some fish, contain creatine.

Medicinal claims: Creatine supplements are used to help people exercise better, increase muscle mass, and decrease fatigue. In some studies, creatine helped muscles perform better during brief, high-intensity exercise.

Possible problems: Creatine can cause nausea, diarrhea, and dehydration, which may lead to kidney problems. How taking creatine continuously for a long time affects the body is unknown. Creatine has no known interaction with other drugs.

Dehydroepiandrosterone

Dehydroepiandrosterone (DHEA) is a steroid hormone produced by the adrenal glands. It is converted into sex hormones, such as estrogen and testosterone. The effects of DHEA on the body may be similar to those of testosterone. In times of stress, the adrenal glands produce DHEA to maintain hormonal balance in the body.

Medicinal claims: DHEA supplements are claimed to improve memory, mood, energy, sense of well-being, and the ability to function under stress. They are thought to stimulate the immune system. Many athletes claim that DHEA supplements build muscles. Other claims include deepening nightly sleep, lowering cholesterol levels, decreasing body fat, and slowing down or reversing the effects of aging. Some advocates think DHEA supplements may help people with Parkinson's disease or Alzheimer's disease function better. These supplements have been used to treat people who have depression (because DHEA levels may be low).

Whether DHEA builds muscle or enhances athletic performance in people with normal adrenal glands and DHEA levels is unclear. There is no reliable evidence that DHEA supplements slow aging or help people who have Parkinson's disease, Alzheimer's disease, or depression.

Possible problems: Use of DHEA supplements may result in breast enlargement in men and hairiness in women. These supplements may also lead to hair loss, a decrease in the level of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol), an increase in the blood sugar level in people with diabetes, and liver problems. When DHEA is used for a long time or in large amounts, it may stimulate the growth of certain prostate and breast cancers. However, none of these effects have been substantiated. For most people, the risks of using DHEA supplements probably outweigh any possible benefits.

Echinacea

Echinacea, also called purple coneflower, is a perennial herb. Various parts of the plant are used medicinally.

Medicinal claims: Several substances in echinacea may stimulate the immune system. Echinacea has been used to help prevent and treat viral infections in the upper respiratory tract, such as the common cold. Applied as a cream or an ointment, echinacea has been used to speed the healing of wounds.

Some evidence suggests that echinacea can reduce the duration of colds, the severity of symptoms, and the frequency and number of recurrences. However, these studies were not designed well enough to provide conclusive results. In a recent well-designed study, echinacea did not prevent or shorten the duration of colds.

Possible problems: Side effects appear to be rare. However, allergic reactions can occur and may be serious. Echinacea should not be taken for more than 8 weeks without a break because daily use for a long time may suppress the immune system. Because echinacea stimulates the immune system, it may cancel out the effects of immunosuppressants (used to treat arthritis and to prevent rejection of organ transplants).

Feverfew

Feverfew is a perennial herb with a daisylike flower. The content of different feverfew products may vary.

Medicinal claims: Feverfew has been used to prevent migraine headaches and treat arthritis. It may reduce inflammation and fever. Feverfew makes blood less likely to clot. Because of this effect, the herb is claimed to reduce the risk of heart attack and stroke.

Some evidence suggests that feverfew is slightly effective in reducing the number and severity of migraines. Feverfew has not been shown to relieve the symptoms of arthritis or to help treat any other disorder.

Possible problems: Feverfew may cause mouth ulcers and skin inflammation (dermatitis). Taste may be altered, and heart rate may be increased. After people stop taking feverfew, they may feel nervous and have headaches, insomnia, and joint pain and stiffness. Feverfew may interact with many drugs.

Garlic

Garlic is a perennial plant, long used in cooking and in medicine. The active component of garlic is allicin. Allicin gives garlic its strong odor and medicinal properties. It is released when garlic is crushed or chewed. Heat and acid can destroy the enzymes that release allicin.

Medicinal claims: Garlic makes blood less likely to clot. Advocates suggest that garlic may thus improve circulation and reduce the risk of heart attack and stroke. Garlic stops microorganisms (such as bacteria) from reproducing. Thus, it has been used as an antiseptic and antibacterial. Garlic has also been used to prevent or treat respiratory infections (such as bronchitis), urinary tract infections, sinusitis, fungal infections, and the common cold. In large doses, garlic is claimed to reduce blood pressure, overactivity of the intestine, and the blood sugar level (slightly).

Advocates suggest that garlic reduces the risk of atherosclerosis and, in people who have atherosclerosis, the buildup of plaque. These claims are based on garlic's effect on high cholesterol levels (a risk factor for atherosclerosis). However, garlic only slightly lowers the levels of total cholesterol and low-density lipoprotein (LDL) cholesterol—the "bad" cholesterol.

Some evidence suggests that garlic may be useful in treating mild high blood pressure (hypertension), but the effect is small. Whether garlic lowers the blood sugar level is unclear. Garlic may reduce the risk of certain types of cancer. However, more studies are needed to substantiate this and the many other claims. Nevertheless, using garlic with other measures to lower cholesterol (including exercise, weight loss, and cholesterol-lowering drugs) may be helpful.

Possible problems: Garlic usually has no harmful effects other than making the breath or body smell like garlic. However, consuming large amounts can cause nausea and burning in the mouth, esophagus, and stomach. Consuming large amounts may also increase the risk of bleeding. Garlic may interact with several drugs.

Ginger

Ginger is a perennial plant, long used in cooking and in medicine. The root of this herb contains substances called gingerols, which give ginger its flavor and odor.

Medicinal claims: Ginger appears to soothe the stomach, relieve intestinal cramps, and reduce inflammation and pain. Ginger has been used to prevent nausea, vomiting, motion sickness, and dizziness (including vertigo).

In studies of how well ginger prevents motion sickness and nausea, the results were inconclusive.

Possible problems: Ginger is usually not harmful. However, some people experience a disagreeable taste in the mouth or a burning sensation when they eat it. Ironically, ginger may increase stomach acid production and cause digestive disturbances. Consuming large amounts of ginger can make the brain function more slowly and cause irregular heart rhythms. Ginger may interact with several drugs.

Ginkgo

The ginkgo is a large tree, often planted for ornamental purposes. As a supplement, ginkgo is derived from the tree's fan-shaped leaves. Ginkgo is available as tea or in extracts.

Medicinal claims: Ginkgo appears to make blood less likely to clot and expands (dilates) blood vessels, thereby improving blood flow. Ginkgo has been used to improve blood flow to the brain and in the lower legs. It is sometimes used to treat dizziness, headaches, noise in the ears (tinnitus), memory loss, concentration problems, and depression. It also is claimed to prevent damage to the kidneys caused by the immunosuppressant cyclosporine.

The active components of ginkgo may prevent the airways from narrowing (constricting). Thus, ginkgo is sometimes used to treat asthma and bronchitis.

In some studies, when people with reduced blood flow in the legs (peripheral arterial disease) took ginkgo, they could walk farther without pain. In some studies, ginkgo stabilized or improved mental and social function in people with mild to moderate dementia, including Alzheimer's disease. In another study, ginkgo improved mental function in healthy older people. But other studies show no benefit. Ginkgo appears to reduce the loudness of tinnitus. The effectiveness of ginkgo in treating other disorders requires further study.

Possible problems: Ginkgo supplements usually have no side effects except mild digestive disturbances and headaches. These effects usually disappear as people continue to take ginkgo. Ginkgo can increase the risk of bleeding. Ginkgo may interact with several drugs.

Ginseng

Ginseng is usually derived from two different species of plant: American and Asian ginseng. American ginseng has milder effects than Asian ginseng. Ginseng is available in many forms, such as fresh and dried roots, extracts, solutions, capsules, tablets, cosmetics, sodas, and teas.

Siberian ginseng is not really ginseng and contains different active components, but it is used in similar ways.

Ginseng products vary considerably in quality. Many contain little or no active ingredient.

Medicinal claims: Ginseng is claimed to enhance physical (including sexual) and mental performance. It is also claimed to increase energy, prevent fatigue, help the body cope with stress, and slow aging. Other claims include reducing the blood sugar level and increasing the level of high-density lipoprotein (HDL) cholesterol—the "good" cholesterol.

In one study of people with diabetes, ginseng reduced the blood sugar level, and people who took ginseng reported that their mood improved and energy increased. In another study, people who took ginseng reported that their quality of life improved. In one study, people who took ginseng appeared to have fewer cases of cancer. However, the results of these studies are inconclusive. Most of ginseng's claims, including improvement of athletic or sexual performance, have not been proved.

Possible problems: Ginseng has a reasonably good safety record. The most common side effects are nervousness and excitability, which usually decrease after the first few days. The ability to concentrate may be decreased, and the blood sugar level may decrease to an abnormally low level (causing hypoglycemia). Occasionally, serious side effects occur. They include asthma attacks, increased blood pressure, palpitations, insomnia, diarrhea, and, in postmenopausal women, vaginal bleeding. In one study, ginseng appeared to stimulate the growth of breast cancer cells. Ginseng may interact with many drugs. If older people are taking several drugs, taking ginseng is not advisable.

Glucosamine

Glucosamine is a component of cartilage. It stimulates cells to rebuild cartilage and helps lubricate joints. As a supplement, it is derived from crab shells or is made synthetically. It is often combined with chondroitin, another component of cartilage.

The contents of glucosamine products vary considerably. Some glucosamine products do not contain any glucosamine.

Medicinal claims: Glucosamine supplements are claimed to relieve pain and increase the range of motion in people with arthritis. Some evidence supports these claims. In one study, the combination of glucosamine, chondroitin, and manganese decreased pain in the knee due to osteoarthritis. A large, well-designed study of the effects of glucosamine (and chondroitin) is under way. It will provide more conclusive evidence. Whether taking glucosamine supplements helps to rebuild cartilage is unclear.

Possible problems: Glucosamine supplements appear to be relatively safe. They may cause some mild digestive disturbances, such as heartburn or nausea. There is some concern that glucosamine derived from crab shells may cause a reaction in people with a shellfish allergy. Glucosamine may affect the blood sugar level. So people with diabetes should talk with their doctor before they take glucosamine.

Goldenseal

Goldenseal is an endangered plant, related to the buttercup. Its active components are hydrastine and berberine.

Medicinal claims: Goldenseal has been used as an antiseptic wash for mouth sores, inflamed and sore eyes, and irritated skin and as a douche for vaginal infections. It has been combined with echinacea as a cold remedy. Goldenseal has also been used as a remedy for indigestion and diarrhea.

The effectiveness of goldenseal as a cold remedy has not been proved. Some evidence suggests that berberine, isolated from goldenseal, may reduce the severity and duration of diarrhea due to a bacterial infection. Berberine may also inhibit the growth of parasites in the intestines. However, goldenseal is not recommended to relieve diarrhea because its other components may irritate the digestive tract.

Possible problems: Goldenseal has many side effects, including digestive disturbances, confusion, contractions of the uterus, and worsening of high blood pressure. Large amounts of goldenseal can cause seizures, respiratory failure, and death. It may affect the contraction of the heart. Goldenseal may interact with several drugs. People who have heart disorders or problems with blood clotting should not take goldenseal.

Horse Chestnut

The horse chestnut is a tree. Supplements are made from the seed. They are available as a tablet, a capsule, or an ointment. The active component is aescin.

Medicinal claims: Horse chestnut supplements have been used to treat chronic venous insufficiency, varicose veins, and hemorrhoids. In these disorders, blood vessels are damaged, allowing fluids to leak from blood vessels into the tissues. The result is swelling. Horse chestnut supplements are thought to strengthen the walls of small blood vessels and thus help prevent leakage. Swelling may then be reduced. Horse chestnut supplements have also been used to relieve swelling after injuries. They are claimed to help prevent bruising, which is common among older people because aging causes blood vessels to become more fragile.

Evidence suggests that horse chestnut supplements relieve leg swelling and pain in people with chronic venous insufficiency. No evidence supports the other claims.

Possible problems: When taken off the tree, seeds of the horse chestnut are poisonous. So people should use only commercial preparations, which are detoxified. Horse chestnut supplements are relatively safe. But because these supplements are used to treat symptoms that may indicate a serious disorder, talking with a doctor before starting to take them is always recommended.

Horse chestnut supplements may irritate the stomach, cause itching, or cause the blood sugar level to decrease to an abnormally low level (causing hypoglycemia). Large doses may cause kidney or liver disorders, so people who already have one of these disorders should not take these supplements. Rarely, horse chestnut supplements cause an allergic reaction.

Human Growth Hormone

Human growth hormone is produced by the pituitary gland, which is located at the base of the brain. This hormone is essential for growth and affects how the body uses energy (metabolism). Production of human growth hormone is greatest during adolescence, then progressively decreases after age 30.

Human growth hormone is available only by prescription and must be injected. Some products that are available without a prescription are claimed to contain substances that stimulate the body's production of human growth hormone. A few are claimed to contain small amounts of the hormone itself. These products are available as a powder, tablet, or liquid taken by mouth, as a topical gel, and as a mouth or nasal spray. These products are highly unlikely to have any effect at all. Also, human growth hormone taken by mouth cannot be used by the body because it passes through the digestive tract without being absorbed. Human growth hormone applied to the skin or used as a spray cannot be absorbed by the body.

Medicinal claims: Human growth hormone is claimed to reverse the effects of aging, reduce body fat, help the heart and immune system function better, lower blood pressure and cholesterol levels, strengthen bones, improve physical (including sexual) performance, and increase energy.

Evidence supports some of the claims for human growth hormone when it is given as an injection. But the effects of long-term use are unknown.

Certain uses of a synthetic form of human growth hormone given by injection have been established. It is approved for use by children whose growth has been stunted. It is also used to reverse muscle wasting (atrophy) in people with AIDS and to treat people who have a deficiency of human growth hormone.

As the body ages, it produces less human growth hormone. Some theories suggest that this decrease may contribute to frailty during old age. As a result, several studies have focused on whether human growth hormone replacement can reverse the aging process by increasing muscle (lean body mass), physical strength, and mobility and thus improve quality of life. Results of these studies have been disappointing, showing no improvements.

Possible problems: Human growth hormone given by injection can cause a high blood sugar level (hyperglycemia), temporary fluid retention, high blood pressure, headaches, carpal tunnel syndrome, mild pain in joints, and excessive growth (acromegaly). It can also cause the thyroid gland to function less well.

Kava

Kava is a shrub that grows in the South Pacific. As a supplement, kava is derived from the dried rhizome (underground stem or root) of the shrub.

Medicinal claims: Kava has been used mainly to relieve anxiety. It has also been used to treat insomnia, restlessness, stress, seizure disorders, and depression.

Evidence suggests that kava, given for a short time, is effective in relieving anxiety and helping with sleep.

Possible problems: The safety of kava is uncertain, especially if used for a long time. Kava may cause serious side effects, including severe liver damage and liver failure. Such effects appear to be rare. Nonetheless, people with liver disorders should not take kava. In a few people, kava causes nausea, headaches, dizziness, or a rash. Kava can also cause drowsiness. After taking it, people should not drive a car or do other activities requiring alertness. People with Parkinson's disease should not take kava, because it may worsen symptoms. Kava may interact with several drugs and with alcohol.

Licorice

Licorice is a perennial shrub. As a supplement, licorice is derived from the root of the shrub. Natural licorice has a very sweet taste. It is used as flavoring in foods, beverages, and tobacco.

Medicinal claims: Licorice is used to suppress coughs, soothe a sore throat, decrease inflammation, and relieve stomach upset. Applied externally, it is thought to soothe irritated skin. Licorice has not been proved to have any of these effects.

Possible problems: Licorice causes people to retain fluids. Frequently taking large amounts of licorice can result in headaches, fatigue, high blood pressure (hypertension), and substantial changes in sodium or potassium levels. People are advised to take licorice no longer than 4 to 6 weeks.

Licorice should not be taken with diuretics (used to reduce the volume of fluid in the body) or digoxin (used to treat heart failure).

Melatonin

Melatonin is a hormone produced by the pineal gland, which is located in the middle of the brain. Melatonin regulates the sleep-wake cycle. As a supplement, melatonin is derived from animal brains or is made synthetically.

Medicinal claims: Melatonin supplements have been used to treat insomnia and help reduce the effects of jet lag. People who are traveling across time zones may benefit from melatonin given on the day or night of departure and for two or three nights after arrival. Melatonin is claimed to help the immune system function better, to prevent cancer, and to help people live longer.

Evidence suggests that melatonin supplements may help prevent or reduce the effects of jet lag in people who are traveling across several time zones. A few studies suggest that these supplements are effective for treating insomnia, but other studies found no benefit. There is no evidence that melatonin can prevent cancer or help people live longer.

Possible problems: Drowsiness may occur 30 minutes after taking melatonin and lasts about 1 hour. Whether melatonin is safe when used for a long time is unknown. Theoretically, a viral infection or prion disease (such as Creutzfeldt-Jakob disease, the human equivalent of mad cow disease) could result from taking melatonin derived from animal brains but not from taking synthetic forms of melatonin. Thus, synthetic forms are a wiser choice than natural forms. Headaches and temporary depression have been reported. In people who are depressed, melatonin may worsen symptoms. The use of melatonin should be supervised by a doctor because it may interact with several drugs.

Saw Palmetto

Saw palmetto is a tree that grows in the southeastern United States. Saw palmetto supplements are derived from the dried berries of the tree. They are available as tea, tablets, capsules, and a liquid extract.

Medicinal claims: Saw palmetto blocks the actions of testosterone, which stimulates growth of the prostate gland. Saw palmetto has been used to treat benign enlargement of the prostate gland (benign prostatic hyperplasia). Other claims include increasing sperm production, increasing breast size, and improving sexual performance.

Evidence suggests that saw palmetto can relieve the symptoms of an enlarged prostate gland, such as the frequent urge to urinate and decreased urine flow. Other claims have not been proved.

Possible problems: Side effects are rare and usually mild. They include headaches and diarrhea.

St. John's Wort

St. John's wort is a plant that grows wild in many areas of the world. The reddish substance in the plant's yellow flowers contains hypericin, which is the main active component. Supplements are available as capsules, liquids, skin lotions, and tea.

Medicinal claims: St. John's wort is used mainly to treat depression. This herb can act like a monoamine oxidase inhibitor (MAOI), an antidepressant. However, St. John's wort, when used as directed, does not seem to have the same side effects or interactions with certain foods. St. John's wort is also used to reduce inflammation and fight infection. It has been used to treat HIV infection, vitiligo (loss of normal skin pigment in patches), burns, insect bites, cancer, bronchitis, and kidney disorders. It has also been used to help wounds heal.

In many studies, St. John's wort relieved symptoms in people with mild to moderate depression. Some of these studies included older people. However, in one large, well-designed study, St. John's wort was no more effective than placebo (a pill with no active ingredients) in relieving symptoms in people with moderate depression. St. John's wort has not been shown to be effective in treating HIV infection or vitiligo.

Possible problems: When used as directed, St. John's wort can make the skin very sensitive to sunlight. St. John's wort inter-acts with many drugs.

Valerian

Valerian is a pink-flowered perennial plant. Valerian supplements are derived from the plant's dried root. Valerian is used to flavor foods and beverages, such as root beer.

Medicinal claims: Valerian appears to have a calming effect. Thus, it is used as a sedative and sleep aid. Some evidence suggests that valerian can improve sleep quality and shorten the time needed to fall asleep.

Possible problems: Valerian occasionally causes headaches, excitability, uneasiness, and heart palpitations. After taking it, people should not drive a car or engage in other activities requiring alertness. Valerian may interact with drugs used to calm or produce drowsiness (sedatives).

See the table Taking Medicinal Herbs and Drugs Together: Some Possible Interactions.