Institute of Medicine Evaluates Safety of Dietary Supplements

The Institute of Medicine, a branch of the National Academy of Sciences, has developed a program at the request of the U.S. Food and Drug Administration (FDA) to evaluate the safety of dietary supplements, according to reports from the Associated Press and Reuters. The Institute's initial task will be to review published safety data on two herbs (chaparral and saw palmetto), a hormone (melatonin), and three nutritional supplements (chromium picolinate, glucosamine, and shark cartilage), all of which are sold in the United States without a prescription.

These six supplements were chosen because of preliminary reports suggesting they can cause adverse effects. Chromium picolinate, for example, which is used to improve blood-sugar control, has been linked to kidney damage. Glucosamine, a natural remedy for osteoarthritis, made the list because of "concerns" about its safety for diabetics.

The fact that certain supplements are being investigated does not necessarily mean they are unsafe. Concerns about glucosamine are based on studies in which it was given by continuous intravenous infusion in relatively large amounts to animals or humans. In these studies, researchers observed transient changes in glucose metabolism that mimicked some of the abnormalities seen in diabetes. However, none of these abnormalities have been reported in humans taking glucosamine orally. On the contrary, in a three-year study of individuals with osteoarthritis, those taking glucosamine actually experienced a reduction (improvement) in their blood sugar levels.

The alleged association between chromium picolinate and kidney problems is also questionable. This link is based on two case reports in which kidney disease developed during or after a period of chromium picolinate supplementation. One of these case reports involved a 49-year-old woman who developed a kidney condition called interstitial nephritis five months after taking chromium picolinate for six weeks. However, the woman was also taking a medication (hydrochlorothiazide) that is known to be associated with this kidney disorder.

In the second case, the affected woman suffered from schizophrenia and depression, so her history in relation to the ingestion of kidney-damaging toxic substances may have been unreliable. In addition, this woman had been taking two psychiatric medications that are known to interact, and that are supposed to be combined only "with caution." Animal studies have failed to identify any adverse effects of chromium supplements on the kidneys, even when given in amounts far larger than those typically used by humans. Some confusion has arisen in relation to chromium supplements, because hexavalent chromium (an industrial compound that differs from the nutritionally essential trivalent chromium) has been linked to kidney damage.

Even if the evidence were to show that some natural substances cause adverse effects, their potential risks would need to be weighed against their benefits. Glucosamine, for example (in the form of glucosamine sulfate) has repeatedly been shown to be at least as effective as, and safer than, commonly used anti-inflammatory drugs in the treatment of osteoarthritis. Chromium picolinate has been found to improve blood-sugar levels in diabetics and may also be useful for individuals with a mild form of depression called dysthymia. In analyzing the Institute of Medicine's report, due to be published in a few months, the FDA should also consider the benefits of these natural products, as well as the toxicity of conventional medications that are used as alternatives to the natural remedies.

Alan R. Gaby, MD, an expert in nutritional therapies, served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the Medical Editor for Clinical Essentials Alert, is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Prima, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Prima, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). Currently he is the Endowed Professor of Nutrition at Bastyr University of Natural Health Sciences, Kenmore, WA.

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