Dietary Supplements : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 4)

Lori A. Love, M.D., Ph.D., director of the clinical research and review staff in FDA's Center for Food Safety and Applied Nutrition, cites as an example white willow bark, which contains a substance the body metabolizes into acetylsalicylic acid, aspirin's active ingredient.

Firms market this botanical as an ingredient in products for children's use. However, unlike labeling for aspirin, labels for these products do not carry the FDA warning that children and teenagers should not use these products if they have symptoms of chickenpox or influenza, because such use has been associated with Reye syndrome, a rare, but serious illness. In fact, Love says, a number of these products are labeled "aspirin free."

Levels of natural constituents in herbs sometimes vary greatly. The concentration of a constituent, for instance, varies with the part of the plant it comes from, growth stage at harvest, and processing and dilution during manufacture. Some ingredients in herbal products naturally contain chemicals that are harmful, such as certain alkaloids.

In other words, "natural" doesn't necessarily mean "safe."

Substances in supplements that have raised safety issues include:

Chaparral: After learning of five cases of chaparral-related acute toxic hepatitis, FDA warned against consuming this herb, and manufacturers voluntarily removed most products containing chaparral from the market. Promoters claim chaparral slows aging, "cleanses" the blood, and treats skin problems' all unproven claims.

Comfrey: Since 1985, at least seven cases of liver disease, with one death, have been associated with oral use of products made from this leafy plant. Comfrey contains pyrrolizidine alkaloids. People who ingest even small amounts of these alkaloids for a prolonged time may be at risk for developing cirrhosis of the liver. Comfrey is sold as teas, tablets, capsules, tinctures, medicinal poultices, and lotions.

Germanium: Use of this nonessential element for a long time may cause serious, irreversible kidney damage and has resulted in death. Germanium products are promoted as so-called "health promoting" elixirs or as an "electronutrient" for uses such as neutralizing heavy metal toxicity. There is no evidence of effectiveness.

Guar gum: Now banned from use as an active ingredient in drugs, this complex carbohydrate that swells when wet has been used in weight- loss products to produce a feeling of fullness. One brand resulted in hospitalization of at least 10 patients and one death from a blood clot after surgery to remove a throat blockage. Guar gum can cause diarrhea, vomiting, bloating, and intestinal blockages.

Jin Bu Huan: Unapproved labeling claims this Chinese herbal product is useful for relieving pain. After accidentally taking Jin Bu Huan, three preschool children were hospitalized this year in Colorado with life-threatening, very slow heart rates, depressed central nervous systems, and breathing difficulties. After intensive medical care, the children recovered.

Ma huang: Products with Ma huang, derived from an evergreen plant, are under investigation following reports to FDA of serious adverse effects such as high blood pressure, rapid heart rate, nerve damage, muscle injury, psychosis, stroke, and memory loss. Ma huang is sold in products for weight control or boosting energy. These products often contain other stimulants, which, taken together, may increase the potential for adverse effects.

Yohimbe: Yohimbe is a tree bark marketed in products for bodybuilding and "enhanced male performance." Serious adverse effects including kidney failure, seizures, and death have been reported to FDA with products containing yohimbe and are currently under investigation.

Nutrients

Like other natural substances, even nutrients may be harmful at certain levels. With vitamins and minerals, there may be adverse effects from excessive potency of certain ingredients, or from contaminants or impurities in these products.

For example, says John Vanderveen, Ph.D., director of the Office of Plant and Dairy Foods and Beverages in the Center for Food Safety and Applied Nutrition, FDA discovered that some calcium supplements contained lead. "They had to be reformulated," he says. "And some calcium supplements had excessive levels of vitamin D, which would have been toxic if taken continuously at this high intake."

Although the margin of safety between the needed level and the toxic level is quite wide for some nutrients, Vanderveen says, it is very narrow for others, such as the mineral selenium.

The agency believes that problems with nutrients can be best handled by subjecting them to the same labeling requirements as other foods.

Known Risks

Some known risks of nutrients consumed at excessive potencies are:

Folic acid: Intakes higher than 1 milligram a day may mask symptoms of vitamin B12 deficiency while pernicious anemia caused by the deficiency progresses undetected.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.