Knowing something about red wine varieties and particular vintages can pay off healthwise. In plants, resveratrol acts as an antifungal. Because fungus is a greater threat in cool, damp climates, grapes grown in such regions produce more resveratrol. Varieties that are most vulnerable to mold and mildew are most prolific -- a Pinot Noir, for example, from the Finger Lakes region of New York or the French province of Burgundy. And, whatever its effect on wine quality, an especially wet growing season boosts resveratrol content.
Older wines are likely to be higher in resveratrol, too. Younger wines may be filtered, a process that removes bitterness but also some resveratrol.
A similar rule holds true for flavonoids. These compounds are concentrated in grapes' skins and seeds. One type of flavonoid in red wine is anthocyanin, which gives red wines their ruby hues. A deeper red indicates longer contact with the skins during fermentation, and thus higher flavonoid content. Drier wines, which are fermented longer than sweeter ones, are likewise richer in flavonoids. Thus, a mature Cabernet Sauvignon would be a better choice than a youthful Beaujolais.
Wine loses resveratrol and flavonoids after the bottle is opened; both compounds are easily diminished by light and oxygen. However, both stand up to the heat of cooking.