Resveratrol is found naturally in red grapes, red wine, peanuts and some berries. It is also sold as a supplement and has been the subject of research into whether this polyphenol plant compound has health benefits due to its antioxidant properties.
There's some evidence that antioxidants may help reduce damage to cell DNA and cell membranes, potentially leading to longer life.
The health claims manufacturers can make about food supplements are regulated by the European Food Safety Authority. EFSA rejected a claim that resveratrol's antioxidant properties contribute to cell protection from the damage caused by free radicals and thus fights skin ageing. It said the claims had not been substantiated.
Possible benefits of resveratrol
Many of the headlines about the possible anti-ageing and disease fighting possibilities for resveratrol have come from laboratory or animal studies rather than evidence from trials involving humans. Some of the conditions that early research suggests resveratrol might help protect against include:
Heart disease. Studies suggest resveratrol may help reduce inflammation, prevent the oxidation of LDL "bad" cholesterol, and make it more difficult for platelets to stick together and form the clots that can lead to heart attacks.
Cancer. Resveratrol is thought by some researchers to limit the spread of cancer cells and trigger the process of cancer cell death (apoptosis).
Alzheimer's disease. Resveratrol may protect nerve cells from damage and the build-up of plaque that can lead to Alzheimer's.
Diabetes. Studies suggest resveratrol may help prevent insulin resistance, a condition in which the body becomes less sensitive to the effects of the blood sugar-lowering hormone, insulin. Insulin resistance is a precursor to diabetes.
Studies on rodents suggest that resveratrol might even help combat some of the effects of an unhealthy lifestyle and lead to increased longevity. Resveratrol-treated mice fed a high-calorie diet lived longer than similarly fed mice not given resveratrol. Resveratrol protected mice fed a high-calorie diet from obesity-related health problems by mimicking the effects of caloric restriction.
More research is needed in all of these areas that remain scientifically unproven.
Because there have been very few studies conducted on resveratrol in humans, doctors cannot confirm any benefits, and they do not know what effects these supplements might have on people in the long-term. So far, studies have not discovered any severe side-effects, even when resveratrol is taken in large doses. However, resveratrol supplements might interact with blood thinners such as warfarin, and nonsteroidal anti-inflammatory medications such as aspirin and ibuprofen, increasing the risk of bleeding.
Because studies remain inconclusive and insufficient it is difficult for consumers to know exactly what they are getting when they buy the product, or whether it is actually effective. There is also no specific dosage recommendation, and dosages can vary from supplement to supplement.
The dosages in most resveratrol supplements are typically far lower than the amounts that have been shown beneficial in research studies. Most supplements contain 250 to 500mg of resveratrol. To get the equivalent dose used in some animal studies, people would have to consume 2g of resveratrol (2,000mg) or more a day.
Research published in 2013 in the Journal of Physiology suggested that resveratrol could offset the health benefits of exercise in older men. Resveratrol supplements counteracted the health effects of exercise on blood pressure, fat in the blood and oxygen in the body.
Until more high-quality research is available, most doctors are unlikely to recommend resveratrol supplements for anti-ageing or disease prevention.