Obesity, Smoking Linked to Faster Aging
Difference seen deep inside cells, say researchers
June 13, 2005 -- Everybody ages, but the pace may pick up with obesity and
A new study isn't intended to be alarming. It has limitations, having only
looked at genetic markers in white blood cells of about 1,100 healthy white
Still, the researchers don't pull any punches. "Our findings suggest
that obesity and cigarette smoking accelerate human aging," write professor
Tim Spector, MD, and colleagues. Spector directs the Twin Research and Genetic
Epidemiology Unit at St. Thomas' Hospital in London. The study appears in
The Lancet's online edition.
Obesity and smoking have both repeatedly been shown to be serious health
hazards. However, they can also be overcome. If Spector's study is right, the
finding may be one more reason to go for a smoke-free life at a healthy weight,
even if it takes hard work and time to get there.
Cellular Aging Study
The women in Spector's study were all twins aged 18-76 years. The group
consisted of 45 pairs of identical twins and 516 pairs of nonidentical
The researchers examined the length of the telomeres in their white blood
cells. Telomeres are the tips of the chromosomes, which contain DNA. They
gradually shorten over a lifetime. That's a normal part of the aging process.
Telomere length was checked by isolating white blood cells from the women's
Smoking and obesity were linked to shorter telomere length, say the
Assuming their results pan out, the researchers were able to estimate the
number of years lost to cigarettes -- or extra pounds.
- The difference in telomere length between being lean and being obese
corresponds to 8.8 years of aging.
- Smoking (previous or current) corresponds on average to 4.6 years of
- Smoking a pack per day for 40 years corresponds to 7.4 years of aging.
Keep in mind that those time spans refer to telomere length, not overall
"Our results emphasize the potential wide-ranging effects of the two
most important preventable exposures in developed countries -- cigarettes and
obesity," write the researchers.
They point out that there was "considerable variation" in telomere
length between participants and call for larger studies on the topic.
"Obesity and smoking are important risk factors for many age-related
diseases. Both are states of heightened oxidative stress…and inflammation,"
say the researchers. That could wear down the white blood cells' telomeres, and
bigger studies should be done to check that, the study notes.
Other researchers have also suggested that telomere length indicates aging.
In May, a small study tied weight gain and insulin resistance to shortened
telomeres. That report appeared in the journal Circulation.
Last November, a study in the Proceedings of the National Academy of
Sciences showed a link between chronic stress and shorter telomeres. A
third study, published in The Lancet's Feb. 1, 2003 issue, showed an
association between shorter telomeres and greater risk of death from heart
disease and infectious diseases.