How quickly are you aging?

From Scientific American:

My-what-long-telomeres-you-have_1 Doctors routinely urge their patients to quit smoking and exercise regularly. But what if there were a blood test that could show smokers and couch potatoes the damage their lifestyle was actually wreak­ing on their chromosomes?

Two groups of prominent researchers have started companies to provide just such a test, which would measure the length of one’s telomeres. Telomeres are caps on the ends of chromosomes, protecting them much as plastic tips on the ends of shoelaces keep the laces from fraying. Whenever chromosomes—the store­houses of our genes—are replicated in preparation for cell division, their telomeres shorten. That shrinking has led many scientists to view telomere length as a marker of biological aging, a “molecular” clock ticking off the cell’s life span, as well as an indicator of overall health. Studies comparing the telomere length of white blood cells among groups of volunteers show distinct correlations between telomere length and lifestyle. Those who exercise regularly have longer telomeres than those who do not. Folks who perceive themselves as the most stressed have shorter telomeres than those who see themselves as the least. Certain diseases, too, correlate with shorter telomeres, including cardiovascular, obesity and Alzheimer’s.

More here.