A Realistic Look at Supplements
BY LEO SEMES, OD, FAAO
Will flax seed oil help my dry eye? Does bilberry keep my cataract from growing? If I take niacin, will it make my age-related macular degeneration better? One of the reasons why we hear these questions is that up to 40 percent of adults take at least one dietary supplement regularly. Conversely, perhaps as few as five percent to 10 percent of patients taking prescription medication reveal that they're taking supplements. More than 29,000 dietary supplements are available and the FDA hasn't evaluated any of them.
Regulate for Safety's Sake
Interest in the regulation of dietary supplements (vitamins, minerals, herbs or other botanicals, amino acids, or a concentrate, metabolite, constituent, extract or combination of these ingredients) has heightened recently with the American Society of Health-System Pharmacists statement urging Congress to require the FDA to regulate supplements in a manner similar to that for prescription drugs. (The potential danger to public health as well as reported interactions of supplements with prescription drugs formed the basis for this statement.)
Efforts to increase awareness of the actions, adverse events and drug interactions of supplements should proceed on all fronts. And who better to educate patients than pharmacists, primary care physicians (optometrists) and internists? Table 1 provides an abbreviated version of the World Health Organization's list of the not-so-trivial side effects.
Who's Keeping Tabs?
The FDA's first proposed rule didn't appear until 2003, and because the FDA doesn't regulate dietary supplements, manufacturers are under no compunction to conform to good manufacturing practices (GMPs). In addition, no standards for purity, safety or efficacy exist either. Some manufacturers voluntarily follow guidelines from such organizations as the National Nutritional Foods Association GMP Certification Program or the US Pharmacopoeia.
On a more positive note, manufacturers are prohibited from making claims that a supplement is effective for the treatment of a specific disease. However, the Dietary Supplement Health and Education Act of 1994 does permit claims suggesting an effect on "structure or function" of the body. For example, the dietary supplement echinacea may carry labeling that it "supports immune health" (function) but not that it "prevents or cures colds" (treating a disease). The problem is that the function attribute is often extended to disease treatment or amelioration.
|COMPOUND||OCULAR SIDE EFFECTS|
|Gingko Biloba||Retinal hemorrhage
|Niacin||Cystoid macular edema|
|Vitamin A||Intracranial hypertension|
Keep Your Guard Up
Until placebo-controlled clinical trials demonstrate efficacy or lack thereof, we should remain cautious about the claims of dietary supplements. Ask patients whether they use supplements and whether they've experienced any ocular side effects or drug interactions. And prepare yourself to answer questions about supplements for every ocular condition from dry eye to age-related macular degeneration.
Keep in mind that pregnant women, children, the elderly and those treated for significant medical conditions may be more susceptible to adverse effects with supplement use.
For references, visit www.clspectrum.com/references.asp and click on document #112.
Dr. Semes is an associate professor at the University of Alabama at Birmingham School of Optometry.