A recent study found that high levels of cardiorespiratory fitness were associated with a 49 percent lower risk for coronary heart disease among individuals who were at high genetic risk for this disease.
IT MIGHT BE MORBIDLY tempting to think that because you have a family history of heart disease, it's not within your power to prevent a possible heart attack in the future. After all, you've been told by your doctor that you're at higher risk for cardiovascular disease.
But as public health experts – and probably your doctor – stress, lifestyle has a big impact on cardiovascular health. And while advice to eat well and be physically active is broadcast to all, new research – and the largest study of its kind published last month in the American Heart Association journal Circulation – also drive home this point. The researchers concluded that high levels of cardiorespiratory fitness – as estimated by an individual's grip strength; monitored, or objective, physical activity; self-reported, or subjective, physical activity; and a treadmill exercise test – were associated with a 49 percent lower risk for coronary heart disease and a 60 percent lower risk for the heart rhythm disorder atrial fibrillation, among individuals who were at high genetic risk for these diseases.
"The more physically active or the more fit you were, the lower risk you had for future cardiovascular disease of all of these types," says the study's senior author Dr. Erik Ingelsson, a professor of medicine at Stanford University.
[See: 10 Heart Health Breakthroughs.]
Experts say given how lifestyle factors and genetics can both affect risk, the findings aren't so surprising. However, the degree to which physical activity can make a difference in this higher risk group, and the continued misassumption that genetic risk equates to a loss of control, make the latest research particularly poignant. "In the general population there is sometimes that assumption that if you're at high genetic risk, you can't do anything about it," Ingelsson says.
In fact, people with a genetic risk for heart disease can still lower their risk overall in various ways. In addition to lifestyle changes like exercising, that includes taking medication where appropriate to lower high cholesterol or high blood pressure, says Dr. Nieca Goldberg, an American Heart Association spokesperson and medical director at the Joan H. Tisch Center for Women's Health at the NYU Langone Medical Center in New York City. "We can lower a person's risk, whether they have a family history or not."
While the research published in Circulation was observational and evaluated overall risk reduction, other studies suggest it's possible for physical activity to lower disease risk even at a genetic level. For example, the obesity epidemic in the U.S. has clear implications for contributing to higher rates of cardiovascular disease and myriad other health problems, from diabetes to cancer. And while it's long been appreciated how physical activity can help prevent weight gain or shed pounds, research also suggests it can modify the effects of the FTO gene – sometimes called the "fat gene" – that puts some people at higher risk of obesity.
A recent meta-analysis of more than 200,000 adults published in the journal PLOS Genetics in April took a genome-wide look at how physical activity might attenuate, or offset, genetic risk for obesity. It identified novel genetic risks for obesity. While researchers were only able to demonstrate the impact of physical activity on reducing the effect of the FTO gene – replicating previous findings – it reinforced the impact exercise can have even at a genetic level.
[See: 8 Weird Ways Obesity Makes You Sick.]
When it comes to evaluating how lifestyle changes like exercising interact with genetic risk for obesity, it's difficult to home in on specific genes (beyond the FTO gene), because the impact each has individually may be relatively small (with the cumulative impact being more significant). "However, we do think that there are behaviors that we do that can definitely influence our genes and make them be expressed or not expressed," says Mariaelisa Graff, a research assistant professor in the department of epidemiology at the University of North Carolina. One example: If you're moving a lot – versus being sedentary – you may have more control over genetic risk for obesity. "We found that genes tend to explain more variance in people that are inactive than active," Graff says. "Physical activity … seemed to somehow attenuate what we're seeing expressed in people that are active, and not so much in people that are inactive. So we do think that there are genes that are influenced by our behaviors, certainly."
Previous research links obesity to a higher risk of at least 13 different types of cancer, including colon, ovarian and breast cancers. For those, as well as other cancers, genetics – or having a family history of the disease – can also increase a person's risk of developing that cancer.
There's no direct evidence showing that exercise affects genetic predisposition for cancer. But it's clear that, as with cardiovascular risk, physical activity can reduce a person's overall risk for various cancers by helping with weight maintenance. In so doing, "we may not be affecting, per se, the gene that's causing cancer – so we're not doing any kind of genetic manipulation," says Dr. Lawrence Wagman, executive medical director of The Center for Cancer Prevention and Treatment at St. Joseph Hospital in Orange, California. "But we are, in fact, doing something that is [addressing] another one of the risk factors."
Cancer, in particular, is an area where experts say people often equate genetic risk with being something like a foregone conclusion. But in fact, Wagman says, what people do has a significant impact on their overall cancer risk – from screening in instances where that may be appropriate to keeping weight under control – even if their genes had raised their risk.
[See: 8 Questions to Ask Your Doctor About Colon Cancer.]
The same essential message, experts say, rings true for other diseases as well. "If you're dealt with bad genetic cards, you can do something about that by being physically active and fit," Ingelsson says. But of course that's not to say you have to be genetically predisposed to a particular condition to benefit from staying active. "Even if you are at low genetic risk," he adds, "you should still do exercise."
