Obesity and smoking speed up aging, researchers said on Tuesday.
They showed that people who smoke cigarettes or are obese have shorter telomeres, the caps on chromosomes that prevent them from fraying, which makes them biologically older than their non-smoking, leaner counterparts.
“Our findings suggest that obesity and cigarette smoking accelerate human aging,” said Dr. Tim Spector, of St. Thomas’ Hospital in London.
Telomeres shorten each time a cell divides. The loss is associated with aging which is why telomeres are thought to hold the secrets of youth and the aging process.
Shorter telomeres
As telomeres get smaller, the chromosomes can become unstable and increase the risk of mutation.
“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 aging and accounts for why these people get heart disease, diabetes, osteoarthritis and other age-related disease,” Spector told a news conference.
Oxidative stress is damage to cells and DNA caused by free radicals — charged particles found in the environment and produced by processes in the body.
Spector and scientists at the University of Medicine and Dentistry in New Jersey compared telomere length from blood samples of 1,122 British women between the ages of 18 and 76.
Nearly 120 of them were obese, 531 had never smoked, 203 were smokers and 369 had quit. The research is published in The Lancet medical journal.
From 4 to 8 years older
The scientists found a decrease in telomere length that corresponded to the more obese the women were and the amount of cigarettes they had smoked.
There was a difference between being obese and lean which corresponded to 8.8 years of aging. Being a current or ex-smoker equated to about 4.6 years and smoking a pack a day for 40 years corresponded to 7.4 years of aging.
“Our results emphasize the potential wide-ranging effects of the two most important preventable exposures in developed countries — cigarettes and obesity,” the researchers said in the journal.
Obesity, which affects about 300 million people worldwide, increases the risk of diabetes, heart disease, stroke and other illnesses.
Researchers have shown that cigarette smokers die on average 10 years earlier than non-smokers but that kicking the habit can halve the risk. Smoking is a leading cause of lung cancer and COPD (Chronic Obstructive Pulmonary Disease), which includes emphysema and chronic bronchitis. It also increases the risk of heart disease.
