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Is resveratrol safe to take?

Effects of the dietary supplement are not covered by long-range studies.

July 13, 2009|Melissa Healy

Like aspirin and the heart medicine digitalis, resveratrol is a plant extract -- one with seemingly powerful and broad effects on living organisms. It acts as a phytoestrogen, mimicking many of the hormone estrogen's effects. In the cells of rodents as well as humans, it disrupts the genetic machinery that gives rise to inflammation and to cancerous tumors. In cell cultures of brain tissue, it even cleans up the tangled amyloid deposits that are the hallmark of Alzheimer's disease.

It is, potentially, a powerful drug.

But unlike aspirin and digitalis, resveratrol qualifies as a dietary supplement, produced and marketed by an industry that operates under far less stringent government oversight than companies producing prescription drugs.

Supplement manufacturers are forbidden to make direct claims that their products will treat or cure diseases in humans. But they are permitted to cite animal research suggesting a product's curative powers, and to claim that their products improve or support the function of healthy bodily processes.

They are under no obligation to demonstrate the safety of their products before they are offered to the public for sale.

Supplement supporters maintain that, if a substance seems to have only positive effects -- as resveratrol seems to -- there's little need to wait for the glacial pace of clinical trials to determine whether resveratrol supplementation is safe. Similarly, a fine-tuning of the precise dose can seem unnecessary as well.

Traditional health experts disagree. "Taking it as a supplement without long-range safety and toxicity studies is foolish," says Dr. Gerald Weissmann, director of New York University's biotechnology study center. Besides, he adds, "you might get terrible pimples, infections or worse" because the touted "antioxidant" agents that resveratrol sets loose in the body to scavenge toxins also function to dampen our defenses against some dangerous bacteria.

Dr. Arthur Grollman, a microbiologist at New York State University at Stony Brook, says people are taking resveratrol -- often in very large doses -- "on faith" that compounds will have the same effects in humans that they do in the lab and in experiments with animals.

On complex biological issues such as aging and the human diseases that come with it, says Grollman, "they rarely do."

Studies now underway will show whether that faith is well founded or illusory. But it will take several years. Among 12 human clinical trials currently underway or recently completed on resveratrol, just two are Phase 3, or advanced human trials, which are designed to establish the safety and effectiveness of a potential medicine against specific diseases (both will test its effectiveness against Alzheimer's disease). The rest are in earlier stages of research, focusing on the safety of a potential medicine in a range of patients.

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melissa.healy@latimes.com

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