The benefits of a Mediterranean diet are extolled once more as Harvard researchers report that compounds found in red wine and certain vegetables may be the key to a longer, healthier life.
The researchers at Harvard Medical School and BIOMOL Research Laboratories claim to have found a way to duplicate the benefits of restricted calories in yeast with two polyphenols, resveratrol and flavones, found in red wine and olive oil respectively.
Calorie restriction - in mammals, reducing intake to 60 or 70 per cent of the normal daily calories - may be one of many mild stresses that trigger beneficial effects, a phenomenon called hormesis, suggest the researchers.
To explain their new findings, the researchers propose that plant polyphenols, which increase in response to stressful conditions, such as dieting, cue organisms to prepare for impending harsh conditions by switching to a more beneficial survival programme.
The findings, reported in the August 24 Nature advanced online edition, revealed that the polyphenol resveratrol extended yeast life span by up to 80 per cent.
In addition to being the most potent of the molecules, in experiments with human cells, resveratrol activated a similar pathway to that in yeast cells requiring SIRT1. This reportedly enabled 30 per cent of the treated human cells to survive gamma radiation compared to 10 per cent of untreated cells.
As the molecules were also active in human cells cultured in the laboratory, the scientists are hopeful that the research will lead to the discovery and development of new drugs to lengthen life and prevent or treat ageing-related diseases.
Other studies have already linked resveratrol to health benefits in certain age-related diseases, including neurodegeneration, cancer and clogged arteries.
The researchers add that for these particular polyphenols, the beneficial effects seem to be independent of their well known antioxidant properties. Instead, the molecules are said to activate sirtuins - a family of enzymes which extend the life span of yeast.
"We think sirtuins buy cells time to repair damage," said molecular biologist David Sinclair, assistant professor of pathology at Harvard Medical School and co-author of the new study. "There is a growing realisation from the ageing field that blocking cell death - as long as it doesn't lead to cancer - extends life span."
"The sirtuin stimulation provided by certain, but not all, polyphenols may be a far more important biological effect than their antioxidant action," added co-author Konrad Howitz, director of molecular biology at BIOMOL, a biochemical reagents company in Pennsylvania in the US.
The team notes that researchers have already found that mice, rats, worms, flies, and yeast all live longer on a low-calorie diet, which also seems to protect mammals against cancer and other ageing-related diseases.