So, definitely a lack of research here. There's also the problem of exactly how resveratrol is introduced to the body. Without clinical trials, we can't really say whether resveratrol as it's present in red wine would be metabolized in any kind of beneficial way. Let's take a look at another possible cancer-fighter for an example: mushrooms. Mushrooms, including common varieties like shiitake and maitake, contain lentinan, a substance that inhibits tumor growth and has been linked to fighting cancer. Except, to get the dose of lentinan you need, don't bother eating a bunch of shiitakes. You have to inject it intravenously on a weekly basis, in quantities far greater than are present in any conquerable pile of mushrooms. Youch. So resveratrol in wine might not actually have the same effect as resveratrol supplements.