If you haven’t already, you will be hearing a lot in the coming years about telomeres—a part of our cellular anatomy that holds dramatic new information about the trajectory of our health and may turn out to provide the single most important biomarker of aging.
A telomere is the protective cap at the end of a chromosome, the thread-like structure that carries the genetic material of our cells. Think of it as akin to the plastic tips that prevent the ends of a shoelace from fraying. Telomeres keep our chromosomes intact, healthy and functioning—allowing them to reproduce cells, which is the key to healthy aging, if not life itself.
It’s the length of a telomere that’s crucial. The longer it is, the healthier you are. And the older you are, the shorter your telomeres generally get. Most cells can replicate about 50 times before their telomeres become too short to protect essential parts of the DNA during the replication process. Once they are reduced to about half the length they were in early adulthood, those critically short telomeres either trigger the aging or death of cells so that they can no longer replicate, or they make normal cells in some tissues susceptible to transforming into cancerous ones.
Telomeres have recently become a valid biomarker of aging as researchers have developed methods to measure them and to evaluate the beneficial effects of therapies to maintain and even increase their length. Indeed, telomere length may well become the first breakout biomarker of aging—so vital to staying healthy and vital longer that it will surpass cholesterol as the number you need to know if you are serious about your health as you get older.
Monitoring and intervening in cholesterol levels was a major advance in its day, and it’s still a useful tool as a snapshot of heart health. But telomere length can tell us so much more—not just about the health of our cardiovascular systems but about all the body’s organ systems, and the body as a whole. Most crucially, while cholesterol does not correlate with age, many studies over the past few years have made a direct association between telomere length, age, and many of the chronic diseases of aging—everything from cancer to dementia.
Researchers have developed a lab test requiring only a simple blood draw to measure telomere length that will become increasingly available in the coming years. And just as drugs like Lipitor have come on the market to lower cholesterol, therapies are being developed to maintain and even increase telomere length as we age. Biotech companies are working on compounds that would activate the enzyme telomerase, building telomeres back up when they get worn down.
Using telomere length as a biomarker involves some nuance. First, it’s the shortest telomeres that tell the story, not the average length of all of them—though it’s also true that if your mean telomere length is short, then your cells are likely to be harboring a greater percentage of critically short telomeres.
And not all telomeres are good biomarkers of aging. The ones we need to look at are only those in cells known as leukocytes— immune cells in blood and lymph tissue commonly known as white blood cells. So the precise biomarker is known as LTL—leukocyte telomere length. Recent research has established an association between LTL and age-related diseases. For instance, it has emerged as a much better indicator than cholesterol for atherosclerosis, the stiffening and narrowing of arteries that is a precursor to heart disease and stroke.
Like cholesterol, telomere length has a heredity component but is generally most affected by environmental and lifestyle factors that influence the attacks and stressors our cells must withstand over our lifetimes. Smokers and people who are obese, or stressed, or don’t eat healthy or exercise regularly have been shown to have shortened LTL. In fact, every bad habit you can think of shortens telomeres, so it is really an integration of all the risk factors for cardiovascular disease—and more.
Research has found that measuring telomeres provides much more information than cholesterol levels about the cumulative oxidative stress and inflammation—the processes that attack and age the cells throughout the body—that an individual has undergone over the years.
The brilliance of telomere length as a biomarker of aging is that it is essentially an historical record of the need for white blood cells to divide to fight off infection or tumors, and of the burden of oxidative stress from the cell-damaging molecules known as free radicals. A cholesterol count can’t give us anything like the record of cumulative damage that a telomere measurement can. It’s why you may not necessarily have problems if your cholesterol is high—but you do have problems if your telomeres are short. It’s also why LTL tells us about our risk for nearly all the diseases of aging, not just cardiovascular disease. And it’s why young people who have their telomeres measured will have a baseline and a way of tracking how they are aging.
Measuring telomere length involves a simple blood draw like any other, though the lab work itself is anything but routine. It costs about $300, but that’s less than it was a year ago, and it’s expected to continue to go down in price as testing becomes more widely available in the next few years.