Dark chocolate may not be the fountain of youth everyone believes it is. (Stephan Savoia/Associated Press)

THE QUESTION Some people tout red wine as a means to a longer, healthier life. Those who like dark chocolate sometimes do likewise. Their conviction stems from a component of both, the antioxidant resveratrol. Does scientific analysis support those beliefs?

THIS STUDY analyzed data from 783 men and women age 65 and older (average age, mid-70s at the start of the study). Participants adhered to a normal Western diet, with resveratrol coming primarily from wine. No one took resveratrol supplements. Laboratory analysis of urine samples revealed the amount of resveratrol that had been metabolized by their bodies.

During the next nine years, 27 percent of the participants who did not have cardiovascular disease at the start developed it, 5 percent of those who had been free of cancer were diagnosed with the disease and 34 percent of the participants died. The likelihood of having died during this span was virtually the same in those who had the lowest levels of resveratrol metabolites, indicating little to no consumption, and in those with the highest levels.

People who consumed the most resveratrol were as likely to have developed cancer or cardiovascular disease as were those who consumed the least.

A study suggests that the antioxidant found in red wine may not make a difference in longevity. (Bigstock)

WHO MAY BE AFFECTED? Older adults. Dietary sources of resveratrol, besides red wine and dark chocolate, include grapes, peanuts, blueberries and cranberries. Most studies on the plant-based antioxidant have been done on animals or involved high-dosage supplements.

CAVEATS Data on dietary sources of resveratrol came from the participants’ responses on questionnaires. The findings do not negate the possibility that wine and other dietary sources of resveratrol have health benefits, but suggest that, if they do exist, they may stem from other components.

FIND THIS STUDY May 12 online issue of JAMA Internal Medicine, archinte.jamanetwork.com/journal.aspx.

LEARN MORE ABOUT resveratrol at www.mayoclinic.org and lpi.oregonstate.edu.

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.