Resveratrol in Wines and Grapes

Resveratrol is strongly associated with red grapes and the red wine made from grapes. Wines such as Malbec, Petite Sirah, St. Laurent and Pinot Noir have the highest resveratrol content. Malbec grapes have the thickest skin, and therefore the highest content of resveratrol.

The concentration of resveratrol in any given red wine depends on the region it comes from. Dark red and purple grapes have a higher concentration of the polyphenol. The concentration in wine varies, however, mostly with the wine-making process used, rather than the type of grape that goes into the wine, however. Traditional wine-making techniques produce the highest concentration of resveratrol in the red wine, when compared to carbonic maceration. For full extraction of various plant pigments and antioxidants from the grape skins and seeds, the wine needs to be in contact with them for a long time, till fermentation is complete. The skins floating on the top should be pushed down repeatedly, when the wine is stirred, so that they and the seeds are in increased contact with the wine. Red wine prepared in this way has the highest resveratrol concentration.

Red wines have a resveratrol content (per 5-oz glass) of 0.03-1.07 mg in contrast to the 0.01-0.27 mg for white wines. Red grape juice contains 0.017-1.30 mg per 5 oz. It is a question worthy of debate whether the known heart-healthy actions of a moderate glass of red wine every day are due to the resveratrol or the alcohol content of the wine.  This is fuelled by the fact that resveratrol has not been shown so far to increase the lifespan or reduce the mortality in a healthy older population.  Yet alcohol has the following independent effects which contribute to reduced atherosclerosis risk and a 20-30% reduction in coronary heart disease:

• Increases HDL
• Lowers LDL
• Reduces blood pressure
• Prevents blood clot formation

Would grape juice produce the same effects as red wine? Apparently, despite the high resveratrol concentrations in the latter, their results in terms of actual health are comparable. What does a healthy glass of red wine mean? It could be translated into 1-2 5-oz glasses of red wine, or just one for women. This is because the female body has a lower water content, leading to a higher alcohol concentration.

Knowing the all-too-familiar side effects of too much alcohol, including alcoholism, liver damage, brain damage, mental problems, diabetes, high blood pressure, stroke and heart disease, as well as cancer, the sketchy correlation between resveratrol and heart health should not be interpreted as a license to imbibe red wine freely. Remember, every red wine has its own alcohol concentration.

Take-home? An after-dinner glass of red wine makes for an enjoyable sip, but more than that is not a healthy practice in view of the evidence gathered so far. Abstainers can still enjoy their shot of resveratrol from non-alcoholic red wine and red grape juice. And alcohol is more likely to be responsible for the heart-healthy effects of red wine than resveratrol, in humans, according to our present state of knowledge. Yet red wine can turn enemy if you take too much of it, because of the adverse health effects of the alcohol in it.

References

• http://www.ajevonline.org/content/47/1/57.abstract
• http://www.scielo.oces.mctes.pt/pdf/ctv/v18n2/v18n2a03
• http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/resveratrol

Further Reading

• Resveratrol - What is Resveratrol?
• Resveratrol Delivery
• Resveratrol Mechanisms
• Resveratrol Supplements