WASHINGTON, Sept 20: Researchers said on Thursday they had found more ways to activate the body’s own anti-ageing defences -- perhaps with a pill that could fight multiple diseases at once.

Their study, published in the journal Cell, helps explain why animals fed very low-calorie diets live longer, but it also offers new ways to try to replicate the effects of these diets using a pill instead of hunger, the researchers said.

“What we are talking about is potentially having one pill that prevents and even cures many diseases at once,” said David Sinclair, a pathologist at Harvard Medical School who helped lead the research.

Sinclair helped found a company that is working on drugs based on this research, Sirtris Pharmaceuticals.

The key is a family of enzymes called sirtuins. They are controlled by genes called SIRT1, SIRT2 and so on.

Last year, researchers showed that stimulating SIRT1 can help yeast cells live longer.

Sinclair, working with colleagues at his company, at Cornell University in New York and the US National Institutes of Health, identified the actions of two more sirtuin genes called SIRT3 and SIRT4.

They found the enzymes controlled by these genes help preserve the mitochondria -- little organs inside of cells that provide their energy.

“These two genes, SIRT3 and SIRT4, they make proteins that go into mitochondria. ... These are little energy packs inside our cells that are very important for staying healthy and youthful and, as we age, we lose them and they get less efficient,” Sinclair said in a videotaped statement.

SLOWING EVERYDAY AGING: “They are also very important for keeping the cells healthy and alive when they undergo stress and DNA damage, as we undergo every day during the aging process.”