Resveratrol is an antioxidant found in grapes, red wine, peanuts, chocolate and certain berries, and it has been credited with a large number of health benefits in various studies. Now, however, a research team presents findings that question whether such benefits come from the compound.
The researchers, led by Dr. Richard D. Semba of Johns Hopkins University School of Medicine, publish their results in JAMA Internal Medicine.
Medical News Today recently reported on a study in which researchers claimed to have identified a mechanism underlying how resveratrol confers health benefits such as preventing heart disease and some types of cancer.
Researchers from that study said resveratrol blocks interleukin 6 (IL-6), a protein in the immune system that can trigger inflammation.
For years, the Western world has marvelled at the so-called French Paradox, which points to the low incidence of coronary heart disease in that population despite their high-cholesterol and high-saturated fat diet. This has been attributed to their regular intake of red wine, with its high levels of resveratrol and other polyphenols.
But this latest study, which assessed a large group of Italians - who consume a diet rich in resveratrol - found that they do not live longer and are just as likely to develop cardiovascular disease or cancer as individuals who consume smaller amounts of the compound.
"The story of resveratrol turns out to be another case where you get a lot of hype about health benefits that doesn't stand the test of time," says Dr. Semba. "The thinking was that certain foods are good for you because they contain resveratrol. We didn't find that at all."
'Dietary resveratrol does not influence inflammation, cancer or longevity'
The team used data on 783 men and women over the age of 65 who were part of the Aging in the Chianti Region study from 1998 to 2009, in order to assess whether resveratrol levels from diet were linked with inflammation, cancer, cardiovascular disease and death.
They measured these levels using mass spectrometry to analyze 24-hour urine samples that looked for breakdown products of resveratrol.
After 9 years of follow-up, the researchers recorded that 34.3% of the participants died, 27.2% developed new cases of cardiovascular disease and 4.6% developed new cases of cancer.
Results showed that resveratrol concentration was not linked with inflammatory markers, cardiovascular disease or cancer rates.
And even after accounting for factors such as age and gender, the team still concludes that those with the highest concentration of resveratrol metabolites were no less likely to have died of any cause, compared with those with no resveratrol in their urine.
The researchers wrap up their study by writing:
"In conclusion, this prospective study of nearly 800 older community-dwelling adults shows no association between urinary resveratrol metabolites and longevity. This study suggests that dietary resveratrol from Western diets in community-dwelling older adults does not have a substantial influence on inflammation, cardiovascular disease, cancer or longevity."
Despite results, other findings show benefits from wine, chocolate and berries
The investigators say their study is the first large, observational epidemiologic study to assess the link between urinary resveratrol from dietary intake and health outcomes in humans.
The strength of their research lies in the population-based sampling and strict criteria for assessing chronic diseases in the participants. Additionally, their measurement of multiple biomarkers for inflammation as well as the high follow-up rates add to the study's strengths.
Participants in the study were not taking resveratrol supplements, says the team, adding:
"Although annual sales of resveratrol supplements have reached $30 million in the US alone, there is limited and conflicting human clinical data demonstrating any metabolic benefits of resveratrol."
But though their study yielded negative results, Dr. Semba notes that other studies have shown that consuming red wine, dark chocolate and berries does have protective effects for the heart and reduces inflammation in certain people.
"It's just that the benefits, if they are there, must come from other polyphenols or substances found in those foodstuffs," he adds. "These are complex foods, and all we really know from our study is that the benefits are probably not due to resveratrol."
In 2013, Medical News Today reported on a study from researchers at the University of Missouri School of Medicine that suggested resveratrol could help treat several cancers.