LOS ANGELES -- Eating less food may help mice -- and possibly people -- live longer by reducing the activity of certain damaging genes in their brains, report scientists from the University of Wisconsin.

The findings should help scientists better understand the tantalising observation that rodents have longer life spans when they are given less to eat.

The study, published on Tuesday in the journal Nature Genetics, used high-tech methods to study more than 6,000 genes in elderly mice kept on either normal or restricted diets.

The researchers found that genes involved in inflammation were less active in the brains of old mice which had been fed less throughout their lives. Inflammation is associated with maladies such as Alzheimer's and Parkinson's disease and may play a role in normal changes of aging.

The activity levels of genes involved in the body's response to stress also were reduced in the elderly mice which had their calories restricted. This implies that restricting calories reduces the amount of stress that the brain is subject to.

The study is landmark, said Dr Caleb Finch, a professor of gerontology and neuroscience at the University of Southern California, who also studies calorie restriction and aging. The findings vastly increase what is known about the effects of caloric restriction, he said.

Studies show that mice and rats live about 30 per cent to 40 per cent longer when their calories are reduced by 30 per cent to 40 per cent. However, Dr Finch said, that does not necessarily pertain to people's diets.

"It's unclear whether this is also applicable to humans, who live vastly longer than the two-year life span of rodents,' he said. Obese people can certainly increase their life spans by eating less, he said, "but whether cutting back daily intake 30 per cent to 40 per cent will slow aging in someone in their 30s, 40s or 50s with good general health is completely unknown." -- AP

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