One of the original researchers involved in telomere length studies is currently publishing a book on general health. It is in no way novel in the lineage of such things save for the relentless emphasis on telomeres, the repeating DNA sequences that cap the ends of chromosomes. Telomeres shorten with each cell division, and stem cells generate daughter cells with fresh, long telomeres, so the average length in a cell type is some function of cell division rates and stem cell activity. The thing is, telomere length as presently measured in immune cells from a blood sample is actually a terrible biomarker (of aging or health status) for individual purposes: the well-publicized erosion of average telomere length with age is a statistical phenomenon that only shows up in the data for large populations, and even there it isn't a robust measure. Pick one individual and their health concerns and it isn't yet at all clear that telomere length measures have any practical utility. Two people with the same condition can have quite different telomere lengths, and changes over time are not yet correlated well with health status for any one individual. This is far worse for use in diagnostic medicine than the sort of long-standing metrics obtained from standardized blood tests at the present time.
Molecular biologist Elizabeth Blackburn shared a Nobel Prize for her research on telomeres - structures at the tips of chromosomes that play a key role in cellular aging. But she was frustrated that important health implications of her work weren't reaching beyond academia. So along with psychologist Elissa Epel, she has published her findings in a new book aimed at a general audience - laying out a scientific case that may give readers motivation to keep their new year's resolutions to not smoke, eat well, sleep enough, exercise regularly, and cut down on stress. The main message of "The Telomere Effect," is that you have more control over your own aging than you may imagine. You can actually lengthen your telomeres - and perhaps your life - by following sound health advice, the authors argue, based on a review of thousands of studies.
Telomeres sit at the end of strands of DNA, like the protective caps on shoelaces. Stress from a rough lifestyle will shorten those caps, making it more likely that cells will stop dividing and essentially die. Too many of these senescent cells accelerates human aging. This doesn't cause any particular disease, but research suggests that it hastens the time when whatever your genes have in store will occur - so if you're vulnerable to heart disease, you're more likely to get it younger if your telomeres are shorter. Other researchers in the field praised Blackburn and Epel's efforts to make telomere research relevant to the general public, though several warned that it risked oversimplifying the science. "I think it's a very difficult thing to prove conclusively" that lifestyle can affect telomere length and therefore lifespan, said Harvard geneticist and anti-aging researcher David Sinclair. "To get cause-effect in humans is impossible, so it's based on associations." Judith Campisi, an expert on cellular aging at the Buck Institute for Research on Aging in Novato, Calif., said the underlying research is solid. "If you have a terrible diet and you smoke, you're definitely shortening your life, and shortening your telomeres. Short telomeres increase the likelihood of cells becoming senescent and producing molecules that lead to inflammation, which is a huge risk factor for every age-related disease. So there is a link there, it's just not this exclusive magic bullet, that's all."
One of the challenges with telomere research is that most studies measure the length of telomeres in blood cells. But it may be that the liver is aging faster or slower than the blood - we're not all one age throughout. By measuring telomere length in the blood, "what you're really reporting on is the capacity of immune stem cells to function well," said Matt Kaeberlein, who studies the molecular basis of aging at the University of Washington. "What this may be really telling us is the immune system may be particularly sensitive to lifestyle and environmental factors." Kaeberlein said he's only at the periphery of telomere research, but is skeptical about the predictive value of shorter versus longer telomeres. "It's not at all clear whether the methods are quantitative enough or of high enough resolution to really make those kinds of arguments. I think it has the potential to be a biomarker predicting health outcomes, but I don't know that I would feel comfortable saying people should make lifestyle changes based on a measure of their telomere length."