When Dr. Nir Barzilai met the 100-year-old Helen Reichert, she was smoking a cigarette. Dr. Barzilai, the director of the Institute for Aging Research at the Albert Einstein College of Medicine, recalled Mrs. Reichert saying that doctors had repeatedly told her to quit. But those doctors had all died, Mrs. Reichert noted, and she hadn’t. Mrs. Reichert lived almost another decade before passing away in 2011.
There are countless stories about people who reach 100, and their daily habits sometimes flout conventional advice on diet, exercise, and alcohol and tobacco use. Yet decades of research shows that ignoring this advice can negatively affect most people’s health and cut their lives short.
So how much of a person’s longevity can be attributed to lifestyle choices and how much is just luck — or lucky genetics? It depends on how long you’re hoping to live.
Research suggests that making it to 80 or even 90 is largely in our control. “There’s very clear evidence that for the general population, living a healthy lifestyle” does extend the life span, said Dr. Sofiya Milman, a professor of medicine and genetics at the Albert Einstein College of Medicine.
One study published last year, which analyzed the lifestyles of more than 276,000 male and female United States veterans, found that adopting eight healthy behaviors could add up to 24 years to people’s lives. They included eating a healthy diet, getting regular physical activity, sleeping well, managing stress, having strong relationships, and not smoking, abusing opioids or drinking to excess.
If the veterans adhered to all eight behaviors, the researchers calculated that they could expect to live to about age 87. To most people, that probably sounds pretty good; after all, it’s almost 10 years longer than the average U.S. life expectancy. But to Dr. Milman, who was not involved in the study, the results showed that “even if you do everything right,” you still can’t expect to live to 100.
If you want to become a centenarian, you’re going to need a little help from your ancestors. Because the older someone gets, the more genetics seem to matter.
Overall, scientists think that how long we live is about 25 percent attributable to our genes, and 75 percent attributable to our environment and lifestyle. But as people near 100 and beyond, those percentages start to flip, said Dr. Thomas Perls, a professor of medicine at the Chobanian and Avedisian School of Medicine at Boston University.
Indeed, studies have revealed that many people with exceptionally long lives don’t have healthier habits than the average American. And yet, they live longer and have lower rates of age-related diseases, like heart disease, cancer and dementia.
In the Long Life Family Study, for instance, “We have families where there’s a lot of smoking; we have some families where they’re couch potatoes,” said Michael Province, a professor of genetics and biostatistics at the Washington University School of Medicine, who leads the study along with Dr. Perls.
But what these families also tend to have are some special gene variants that experts think help them avoid disease and live longer.
Some genes may affect people’s likelihood of developing specific conditions. For example, the APOE gene is known to influence the risk for Alzheimer’s disease: Those who carry the APOE4 variant have an increased risk, while those with the APOE2 version are at a decreased risk. Dr. Province said that long-lived families have a higher prevalence of APOE2 than the average population.
Other genes appear to influence the aging process itself. One that has cropped up in several studies of centenarians is called FOXO3, which is involved in many fundamental aspects of cellular health. Because these genes affect the biology of aging, it’s possible that they can protect against multiple age-related diseases, Dr. Milman said.
One key benefit of these types of longevity genes might be counteracting unhealthy behaviors. A study that Dr. Milman and Dr. Barzilai conducted comparing the offspring of centenarians with a control population found that, across the two groups, those with healthy lifestyles had a similarly low prevalence of cardiovascular disease. But among those with unhealthy lifestyles, the centenarian offspring still had low rates of disease, while the control group did not.
The experts emphasized that many of these genes are very rare, likely occurring in less than one percent of the population. (Probably not coincidentally, a similarly small percentage of people make it to age 100.) There’s also not one single gene that offers protection against all of aging and age-related diseases; it’s more likely that there are hundreds that combine to make a difference.
Having the right set of genes to impact longevity is “like winning the lottery,” Dr. Perls said. So even if your mother made it to 100, you should still practice behaviors you know are good for you, just in case you didn’t hit the genetic jackpot.
And whatever you do, don’t take health advice from a centenarian. For them, lifestyle probably didn’t matter much, Dr. Barzilai said. For the rest of us, it really does.