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New human trials on resveratrol misleading

New human trials on resveratrol misleading

Animal-based resveratrol research is very intriguing: Gains in life span, exercise endurance, neuroprotection and weight management are all reported benefits.

Hype for resveratrol starts with the oft-mentioned theory that it’s the polyphenol responsible for the “French paradox” health benefit of red wine. This is not true. The resveratrol content of red wine is barely 1 mg per glass. However, animal-based resveratrol research is very intriguing: Gains in life span, exercise endurance, neuroprotection and weight management are all reported benefits. Well into 2009, no published results from human resveratrol trials were available, although clinicaltrials.gov listed ongoing human trials for conditions such as metabolic syndrome, melanoma, Alzheimer’s disease and colon cancer.

The 4th International Conference on Polyphenols and Health in 2009 saw the first reporting on function-related clinical-trial results with resveratrol products. One study reported that single doses of 30, 90 and 270 mg of resveratrol led to dose-related increases in plasma resveratrol and flow-mediated dilation, a measure of arterial flexibility. Another reported that single doses of 250 and 500 mg of resveratrol led to increased cerebral blood flow during performance of cognitive tasks. Look for publication of these and other trials in peer-reviewed journals.

Companies offer “resvera-” named products with resveratrol from Japanese knotweed at doses ranging from 50 to 200 mg a day. The U.S. Food and Drug Administration has issued a few warning letters for resveratrol products that make too-ambitious health claims. Sirtris Pharmaceuticals and other companies are actively researching synthetic versions of resveratrol for longer half-life and higher potency, but any FDA approval of these drugs is years away. If or when that happens, expect regulatory pressure on resveratrol-containing dietary supplements to increase.

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