Dietary Supplements : Part 3

by Food and Drug Administration (FDA)

(Page 3 of 4)

Iron: As few as six high-potency iron tablets could seriously injure a child weighing 22 pounds or less. Iron is the most common cause of U.S. child poisoning deaths, causing about 2,000 poisonings a year, mainly in young children taking their mothers' prenatal supplements.

Niacin: High intakes can damage the liver and cause severe gastrointestinal problems.

Selenium: High intakes can damage tissue, especially in tissues or organs where selenium concentrates. Toxicity depends on the chemical form and the selenium content of the foods eaten and has occurred with high intakes after a few weeks.

Vitamin A: Continuous high intakes can cause headaches, liver damage (including cirrhosis), bone damage, diarrhea, and, during pregnancy, birth defects.

Vitamin B6: High intakes can cause bone pain, muscle weakness, numbness, or other symptoms of nerve disorder.

Vitamin C: Very high intakes can cause diarrhea and may cause urinary tract problems.

Vitamin D: Continuous high intakes can cause kidney damage and bone deformity. Underreported Reactions

Just because there haven't been a lot of reports of adverse effects associated with use of dietary supplements doesn't necessarily mean they're safe. A person taking a supplement may not associate an adverse effect with it, especially if the individual also is taking one or more medications or is chronically ill. For example, muscle weakness or numbness caused by too much vitamin B6 might be ignored as a sign of conditions associated with aging. Or adverse effects may take time to develop, so that it's difficult to link them with a specific supplement.

Sometimes, reactions may not be recognized unless large numbers of people are using the supplement. In 1989, for instance, the use of the essential amino acid L-tryptophan was associated with an outbreak of an illness called eosinophilia-myalgia syndrome (EMS), a serious connective tissue disorder. More than 1,500 EMS cases, including 38 deaths, have been associated with L-tryptophan ingestion.

All marketed products to which manufacturers had added L- tryptophan were recalled, except for specific medical foods or infant formula products, which require L-tryptophan to provide adequate nutrition. FDA issued an import alert to prevent importation of the raw material, except for those certain permitted uses.

Initial studies suggested that the cause of the outbreak was an impurity or other component in the product from a particular Japanese manufacturer. Today, however, the exact cause of EMS remains uncertain, despite intense research in this area.

"Cases of EMS, as well as a related illness, eosinophilic fasciitis, were associated with the use of L-tryptophan even before the 1989 EMS epidemic," Love says. "And cases of EMS and related illnesses have occurred with the use of a compound [L-5-hydroxytryptophan] that's similar to L-tryptophan, but not manufactured with the same fermentation process and, therefore, not associated with the same impurities."

Thus, Love says, FDA believes the overall findings point to multiple factors, including L-tryptophan itself, as playing a role in the cause of EMS.

Approaches to Safety

FDA last June published a notice (along with the NLEA-based proposals) to solicit public comment and scientific data on the best approaches to ensuring the safety of dietary supplements, particularly amino acids and botanical products.

The notice summarized the report of FDA's Dietary Supplements Task Force on alternatives for regulating supplement products. The task force made 20 recommendations, including stricter amino acid regulation, required good manufacturing practices for supplements, and stronger adverse reaction reporting requirements for supplements.

However, FDA Deputy Associate Commissioner for Regulatory Affairs Gary Dykstra, who headed the task force, points out, "Contrary to claims by FDA critics, we have no plans to close health food stores, and we aren't going to take safe, properly labeled supplements off the market or make all supplements available only by prescription. The agency favors personal choice as much as possible within the constraints of the FD&C Act."

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.