How Old Is Your Immune System?

Credit: Photograph by Adam Levey

Getting sick screws you twice. There's the suffering in the moment, of course. But every time you get an infection, no matter how minor, your immune system has to produce millions of T-cells to destroy the virus or bacteria. "The more colds you get," says Raffaele, "the more you have to crank up that cell replication and the faster the immune system ages." The overtaxed T-cells apparently lose the ability to divide, and instead of dying off to make room for new cells, they hang around, clogging and slowing the system. (This is why a bad flu can lay you low for weeks and, in later years, usher in fatal pneumonia.) In a brutal one-two punch, these old cells also secrete inflammatory chemicals that can chip away at the health and function of every organ in the body, to such a degree that some researchers call the process of aging "inflamm-aging." The more you avoid germs and tamp down inflammation by eating and exercising right, the slower you'll inflamm-age.

Recently we've unearthed a stranger part of the immune system's story, a virus called cytomegalovirus (CMV), which has two insidious traits. First, CMV is seemingly ubiquitous — a 30-something man has about a 50-50 chance of having it, and by his eighth decade, it's virtually a sure thing. Also, CMV has no symptoms, and the body has little ability to get rid of it. So the virus functions as an endless diversion, siphoning off immune cells to neutralize it. Raffaele likens CMV to a "slow-motion HIV." Whereas HIV kills off T-cells, CMV ages those cells before their time, making you far more vulnerable to infections, cancer, and even heart disease.

The rub: You can contract CMV the same way you would a cold or flu virus, and if you do, you have it for life. But testing for CMV still makes sense. The later in life you pick up the virus, the less time it has to wear down your immune system. And testing negative, should you be so fortunate, is motivation to keep it that way.

There's one more piece to this puzzle — telomeres. These are bits of DNA that protect chromosomes from damage when a cell divides (picture the protective plastic at the ends of shoelaces), allowing immune cells to keep dividing and fighting infection. You're born with a set length of telomeres, so how well your immune system ages is partly genetic luck. But lifestyle also matters: Telomeres shrink over the years, but a bad diet, too little or possibly too much exercise, and high stress can speed the loss.

New technologies have sprung up to measure telomere length, and accordingly, Raffaele gives patients a Telomere Age. That's how competitive runner Jeff Dengate, 39, discovered that, while he has the heart and lungs of a 20-something (he runs a sub-five-minute mile), he has the telomeres of a 52-year-old. "It means his body's ability to repair itself over time is not great," says Raffaele. The result: When telomeres hit a critically short length, the body can no longer repair the damage of getting older and disease creeps in.

Telomere science is in its infancy, and even though we know that exercise is associated with longer telomeres, we don't know if Dengate's aggressive running (25 marathons to date) is shortening his faster than average. Short telomeres are linked with middle-age heart attacks, which run in Dengate's family.

How to Better Your Immunity

Be a (Sensible) Germophobe

Basically, give your immune system less to do. We touch our faces some four times an hour: Be careful not to do so after touching surfaces already handled by hundreds of people, many of whom may harbor CMV or other viruses. Also, make handwashing a habit, particularly before you eat.

Manage Stress

When cortisol, our primary stress hormone, stays too high too long, our production of disease-fighting immune cells tanks. That's why chronic stressors like work demands or family problems are a prescription for illness, whether it's seasonal flu or something worse. Meditation, with its focus on deep, steady breathing, is proved to be effective at lowering stress. (Research shows it can also boost immunity and telomere length.)The stress-busting advice Raffaele gives his numerous Wall Street clients: Cut back on constant and cortisol-jacking intense exercise. You need at least one rest day between hard workouts; otherwise you up bodywide inflammation.

Get More Aminos

Whey protein powder can boost the amino acids, which are known to protect and enhance immune function. An amino-acid supplement, glutamine, is another option, as is quercetin, an antioxidant found in colorful fruits and vegetables.

Here is your guide to assessing — and slowing — everything from your cognitive age to your metabolic decline. 

What Is Your Cognitive Age?

How Old Are Your Lungs?

What Is the Real Age of Your Heart?

How Has Your Metabolism Changed with Age?