Contamination

Dietary supplements may contain harmful or undesirable substances such as pesticides or heavy metals. Contaminants may be present before a substance is harvested for use as a dietary supplement or may be introduced during processing and packaging.
For example, coral calcium, a dietary supplement said to contain remnants of living coral reefs, may contain significant and harmful amounts of lead and other heavy metals. Consumption of excessive levels of lead can cause neurological problems, increased blood pressure, reproductive impairment, and hearing and sight problems. Scientists are also concerned that people who are allergic to shellfish may experience serious adverse events such as hives, swelling, and breathing problems, because of the presence of these allergens in coral reefs.
In 2003 the Sports Nutrition Working Group of the International Olympic Committee Medical Commission reported that approximately one in five dietary supplements commonly used by athletes were contaminated. Protein powders; amino acid supplements; creatine; pyruvate; and several vitamin, mineral, and herbal supplements were found to contain steroid-like chemicals that were not identified on product labels, caused positive doping tests, and were not known to be safe.
Dietary supplements may also contain controlled substances. Acetaminophen, aspirin, antihistamines, and cortico-steroids have been found in dietary supplements that did not list them as ingredients. In 2005 the FDA issued a warning about a dietary supplement that contains the antidiabetic agent glyburide after it caused hypoglycemia (dangerously low blood sugar) in several consumers. In 2006 the FDA warned consumers against using several weight-loss dietary
supplements that contain chlordiazepoxide HCl (the active ingredient in the drug Librium) and fluoxetine HCl (the active ingredient in the antidepressant Prozac).