A new pill, which, if taken at 40, could boost a person's chances of living longer is being developed by scientists.
Prof Nir Barzilai, director of the Institute of Ageing at the Albert Einstein College of Medicine in New York, said that one can go on to live for 100 years despite following a poor diet and even smoking, only if their genes are programmed for longevity.
Those who lived very long lives were genetically programmed to do so, which insulated them from the effects of "environmental" factors like smoking and a poor diet.he professor studied 500 Jewish people between 95 and 112.
"These people smoked, they are overweight, they have high cholesterol," the Telegraph quoted him as saying.
He said about 30 per cent of them were obese, while 30 per cent of them had smoked to the age of 95.
"They are protected from the environment by their genotype," he said.
Living a healthy life might help most people increase their life expectancy by a few years, but it won't be of any use for those who wanted to live much longer, he said.
His findings support anecdotal stories of countless people who have lived to a grand old age seemingly in spite of smoking, lack of exercise or a poor diet.
He said that centenarians tended to have genes, which delayed the onset of age-related illnesses like heart disease and Alzheimer's.
"When they eventually die, they die of the same things that people die of in their 70s or 80s. It's just that they die 30 years later," he said.
Identifying these genes opened the doorway to developing longevity drugs, which mimicked their effects, he said.
The researchers have already identified a number of such genes among the centenarians.
Laboratories are now working on creating a drug which mimics the effects of three of them - two that increase the production of so-called 'good' cholesterol in the body, which reduces the risk of heart disease and stroke, and a third that helps prevent diabetes.
Barzilai said that testing could begin by 2012, with it appearing on the market "within five or 10 years".
"People will take a pill, starting at 40, and their lives will be longer," he predicted.
Barzilai will address the Royal Society in London on the subject of 'interfering with ageing to treat ageing-related disease'.