The scientists from University of Wisconsin-Madison found in a study with mice that a diet supplemented with the compound resveratrol starting at their equivalent of middle age slowed the ageing process down.

Grapes and red wine have an abundance of resveratrol and some research has shown that in high doses, resveratrol extends the life span of fruit flies and worms and prevents early death in mice fed a high-fat diet.

For this study the mice were given relatively low doses of resveratrol but still experienced important ageing-related benefits say the researchers.

The mice began the resveratrol diet when they were 14 months old (middle age for mice) and were then followed until they were about 30 months old (old age).

Tests then conducted to assess cardiac function and gene activity related to ageing, revealed that low doses of resveratrol can retard some aspects of the ageing process, including heart ageing.

The effect of resveratrol was seen to be stronger in the heart than in the brain and muscles, but did prevent some ageing-related changes in the other tissues.

The researchers suspect resveratrol works by mimicking some of the effects of caloric restriction, which is known to retard ageing in several tissues and extend life span.

Other research has shown that animals on a diet where the caloric intake is greatly reduced have also lived longer than animals with normal diets.

But as the the researchers say perpetual hunger is a heavy price to pay for greater longevity.

Most striking say the researchers, was how the resveratrol, like calorie restriction, blocked the decline in heart function typically associated with ageing.

According to Tomas Prolla, a professor of genetics who helped lead the study, it is highly likely that the findings are applicable to humans and more research can be expected in future on the effects of resveratrol supplementation in people.

The study is published in the scientific journal PLoS ONE.

To conduct the study, the researchers analyzed data from more than 30,000 licensed pesticide applicators participating in the Agricultural Health Study, a prospective study following the health history of thousands of pesticide applicators and their spouses in North Carolina and Iowa. The 31,787 applicators in this study included those who completed an enrollment survey about lifetime exposure levels, were free of diabetes at enrollment, and updated their medical records during a five-year follow-up phone interview. Among these, 1,171 reported a diagnosis of diabetes in the follow-up interview. The majority of the study participants were non-Hispanic white men.

Researchers compared the pesticide use and other potential risk factors reported by the 1,171 applicators who developed diabetes since enrolling in the study to those who did not develop diabetes. Among the 50 different pesticides the researchers looked at, they found seven specific pesticides ” aldrin, chlordane, heptachlor, dichlorvos, trichlorfon, alachlor and cynazine - that increased the likelihood of diabetes among study participants who had ever been exposed to any of these pesticides, and an even greater risk as cumulative days of lifetime exposure increased.

All seven pesticides are chlorinated compounds, including two herbicides, three organochlorine insecticides and two organophosphate pesticides.

"The fact that all seven of these pesticides are chlorinated provides us with an important clue for further research," said Kamel. Previous studies found that organochlorine insecticides such as chlordane were associated with diabetes or insulin levels. The new study shows that other types of chlorinated pesticides, including some organophosphate insecticides and herbicides, are also associated with diabetes. The researchers also found that study participants who reported mixing herbicides in the military had increased odds of diabetes compared to non-military participants.

Reference:Montgomery MP, Kamel F, Saldana TM, Alavanja MCR, Sandler DP. Incident diabetes and pesticide exposure among licensed pesticide applicators: Agricultural Health Study 1993 “ 2003, Amer J Epidemiol, 2008;167:1235-46.

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