Red wine contains approximately 5 mg/L of resveratrol, whilst white wine has much less - the reason being that red wine is fermented with the skins, allowing the wine to absorb the resveratrol, whereas white wine is fermented after the skin has been removed (source: Wikipedia)
It has not been sufficiently proven that red wine has a protective effect against stroke in humans but this does not stop people from buying resveratrol capsules on the Internet.
According to researchers, you have to drink about 2 glasses of wine in order to consume the "required" amount of resveratrol. Currently, the content of the food supplements is not FDA-regulated, which means that those resveratrol capsules you bought on the web for $ 30 may not contain resveratrol at all.
The "R" mnemonic:
Reduces stroke area in mice by 40%
Red wine can help prevent stroke damage: study. Reuters.com.
Light-to-Moderate Alcohol Consumption and the Risk of Stroke among U.S. Male Physicians. NEJM, 1999.
Resveratrol: a molecule whose time has come? And gone? Clin Biochem. 1997 Mar;30(2):91-113.
A toast to lower cholesterol. U.S. News & World Report.
Resveratrol, from Wikipedia, the free encyclopedia, public domain.
Wine, from Wikipedia, the free encyclopedia.
Health Blog Interview: CEO, Red Wine in a Pill, Inc. WSJ Health Blog, 11/2007.
Doubt on Anti-Aging Molecule as Resveratrol Trial Is Halted http://goo.gl/wpY0i