Resveratrol is a substance found in grapes and other plants. Many of the supplements on the market extract it from the Japanese knotweed plant, which is a plentiful and inexpensive source. Switzerland's Royal DSM NV sells a synthetic version called resVida, which is found in supplements, a nonalcoholic fruit-flavored beverage and the new Winetime chocolate-fruit bar.

Resveratrol has found been found in animal studies to prevent or slow progression of illnesses from cancer to cardiovascular disease-and even to extend the life span of some organisms. Since 2008, at least five human studies have been presented at scientific meetings showing human benefits, ranging from improved blood flow to the heart to better control of diabetes.

The newest results are exciting, but some scientists say it is too early for the public to begin taking supplements, which contain as much resveratrol in one pill as dozens or hundreds of bottles of wine, depending on the dose. The proper dose for humans isn't yet known-and more isn't necessarily better.

While some safety studies have been conducted on humans, it is too early to know if there are long-term side effects of high doses, says S. Jay Olshansky, a professor of epidemiology at the University of Illinois at Chicago. "I cannot emphasize enough: Do not experiment on your own body," he says.

No one knows exactly how resveratrol works, but scientists believe it activates a wide range of genes, creating a cascade-like effect on a variety of body functions. Human data include a 100-person placebo-controlled study by Sirtris Pharmaceuticals Inc. that found lowered blood-glucose levels in diabetics who took the GlaxoSmithKline unit's proprietary formulation, SRT501, not yet on the market.

A 19-person study presented earlier this month at a British scientific conference, sponsored by Royal DSM, found that "flow mediated dilation," a measure of cardiovascular health, increased an hour after taking resVida. At an American College of Sports Medicine conference last year, Dr. Maroon and colleagues reported that a three-month study of 51 people found a resveratrol-containing supplement not currently on the market increased endurance on a stationary bicycle compared with a placebo, and also increased verbal memory scores on a standardized test.

Resveratrol是一种在葡萄及其它植物中发现的一种物质。市场上很多补品是从日本紫菀科植物提取出来的，这些植物数量多但不是很贵。瑞士的皇家DSM NV出售被称作resVida合成的产品，在补品中发现了它，一款不含酒精的水果味的饮料及新的Winetime巧克力水果棒。

Resveratrol 在动物研究中被发现，用于阻止或降低从肿瘤到心脏血管疾病的发展，甚至用于延长一些生物体的生命。自从2008年以来，至少有5例人类的研究在科学会议上提出展示人类的益处，改善到心脏的血流以更好地控制糖尿病。

最新的结果是令人兴奋地，但一些科学家说，对于公众来说开始摄入这种补品尚早，依据剂量的不同，这种补品一丸中含有大量的resveratrol或是相当于成百瓶的葡萄酒。对于人类的合适的计量还是未知，而且并不是越多越好。

虽然已从事人类的安全方面的研究，但现在还不能确定是否大剂量会对人体造成长期的副作用。S. Jay Olshansky,说，芝加哥的伊利诺斯州大学的流行病学教授。"我要强调的是：不要在自己的身体上做实验。"

没有人知道resveratrol 怎样起作用，但科学家相信它使大范围的基因充满活力，对于不同的身体功能产生影响。人类数据包括由Sirtris Pharmaceuticals Inc.进行的100人的安慰剂控制的研究发现，糖尿病患者在摄入了SRT501（还未上市）后血糖水平降低。

本月早些时候，在英国科学大会上，由皇家DSM发起的一个19人参加的研究发现流动缓解膨胀，心脏血管健康的措施，在摄入resVida后一小时增强。在去年美国大学体育药物大会上，Maroon博士和他的同事报告了51人为其三个月的研究发现含有resveratrol的目前还未上市的补品与安慰剂相比可以增加在固定自行车上的耐力，也可增加标准测试上的大脑记忆力分数