Smoking and obesity can increase the rate of biological ageing by shortening the length of telomeres, which are caps on chromosomes that keep them from wearing away, a study has found.
“Our findings suggest that obesity and cigarette smoking accelerate human ageing,” said Dr Tim Spector of St Thomas’ Hospital in London, lead author of the study.
The length of telomeres becomes shorter every time cell division takes place. The shorter the telomeres become, the greater are the chances of the chromosomes being rendered unstable and of cell mutations taking place.
Under the study, Spector and his team measured the concentrations of leptin, which is a regulator of body fat, and the length of telomeres in the blood of 1,122 women aged between 18 and 76 years. Out of these around 120 were obese, 531 were non-smokers and had never smoked, 203 were regular smokers and 369 had quit smoking.
Researchers found that the length of telomeres in women who were obese and those who smoked regularly were significantly shorter than non-smokers and those who maintained healthy weight.
The difference indicated by the length of telomeres between lean and obese women was found to be around 8.8 years. Women who smoked or were smokers earlier were found to have biologically aged 4.6 years faster than non-smokers. Those who smoked one whole packed per day for 40 years were found to have aged 7.4 years faster than those who were non-smokers.
“Obesity and cigarettes cause oxidative stress to increase and this cumulative damage over time causes the loss of these telomeres, which we believe is a marker of accelerative ageing and accounts for why these people get heart disease, diabetes, osteoarthritis, Alzheimer’s and other age-related disease,” Dr Spector said.
Oxidative stress is the term given to the damage wreaked on the DNA and cells by free radicals, which are by-products of certain chemical reactions in the body.
“Our results emphasize the potential wide-ranging effects of the two most important preventable exposures in developed countries – cigarettes and obesity,” Dr Spector said, adding, “If you’re an obese smoker you will be at least 10 years older, biologically. Every cigarette smoker knows they’re going to die early. The new message is it’s not only your heart or lung cancer that’s going to get you, it’s your whole body that’s being damaged. Your chromosomal clock is going faster.”
The study has been published in medical journal
The Lancet.
