Healthy lifestyle makes it possible to outsmart your genes
Your genes are not necessarily your destiny – at least when it comes to the risk of heart disease.
Researchers at Massachusetts General Hospital in Boston and colleagues recently showed that living a healthy lifestyle makes it possible to outsmart your genes and significantly reduce the number of heart attacks and other heart issues.
The study, published last November in the New England Journal of Medicine, is one of the American Heart Association’s top 10 heart and stroke science advances of 2016.
Doctors have long preached the importance of healthy lifestyle habits to improve heart health, especially for those with a family history of heart disease. But until now there has never been a systematic evaluation of how – or even if – genetic risk and lifestyle interact to impact a person’s overall risk, according to lead researcher Amit V. Khera, M.D., a cardiologist and genetics researcher at Massachusetts General Hospital.
Study researchers looked at DNA from 55,685 healthy individuals from four studies to determine who had the highest genetic risk for developing heart disease. There are at least 50 genetic variants across the entire genome that can play such a role, said Khera.
Next, they rated how healthy these people were based on four lifestyle factors: no smoking, no obesity, regular exercise and a healthy diet. Then they calculated each group’s 10-year risk of having a heart attack, needing a procedure such as coronary artery bypass or dying from a heart-related cause.
After crunching the numbers the researchers determined that, regardless of the genetic hand they’d been dealt, people who lived a healthy lifestyle lowered their risk by nearly 50 percent compared to those with an unhealthy lifestyle. For example, in one cohort of people at high genetic risk, the rate of coronary events dropped from 11 percent for those with an unfavorable lifestyle to only 5 percent for those who took better care of themselves.
In another study of mostly healthy women, the rate fell from 4.6 percent in the unhealthy group to 2 percent among the healthiest in the segment of women at high genetic risk.
“In every instance, a healthy lifestyle cut risk significantly, whether heart disease runs in your family or you won the genetic lottery,” said Khera.
Researchers set a relatively low bar for what constituted a healthy lifestyle. Hitting three out of four health goals qualified as having a “favorable lifestyle,” and the exercise goal only required strenuous exercise once a week.
“About 40 percent of the people we looked at met this once-a-week exercise standard,” he said. “Had we gone with the stricter government recommendations of exercising three times a week, the impact of a healthy lifestyle would have been even more significant.”
The study, said one heart expert, should provide encouragement for those trying to get healthy.
“It should give hope and strength to people struggling to kick their smoking habit, eat better, lose weight and get more exercise,” said Jennifer L. Hall, Ph.D., chief of the AHA’s Institute for Precision Cardiovascular Medicine.
“And for those who may not believe or understand the impact of their daily lifestyle choices on their health, this study may make a big difference,” Hall said.
As a clinician, Khera said the study will give him ammunition in the form of hard numbers to give patients, even those with a history of heart disease, that lifestyle changes can lower their risk.
“That’s a message physicians have been telling patients for years, because it made sense and seemed logical,” he said. “Now we have actual numbers to provide.”
The study findings may also lead to more targeted interventions – from lifestyle improvements to drug therapy – for those at high genetic risk.
Genetics are totally independent of other heart disease risk factors, such as age, gender and smoking, Khera said. Although genetic tests are not widely available, researchers are building smartphone apps to determine a person’s risk score from direct-to-consumer genetic testing.
“We looked systematically at the extent to which a favorable lifestyle could offset high genetic risk,” he explained. “That’s why this study is so important.”
Until genetic testing becomes commonplace, Khera recommends people give themselves what he calls the “poor man’s DNA test” and simply look at family history of heart disease.
If heart attacks run in your family, he said, “you may want to talk with your doctor or cardiologist about lifestyle changes and medication to decrease your risk.”
The study had several limitations. First, it was a prospective observational study, meaning it followed people over time to see what happened based on existing behaviors instead of randomizing them into good or bad lifestyles.
It also focused on common genetic variants that affect heart health. More rare conditions, such as familial hypercholesterolemia, which causes extremely high cholesterol levels and increases coronary heart disease risk more than 10-fold, may not respond as dramatically to lifestyle changes alone.
Although the study examined only heart disease, Khera said improving lifestyle may have other benefits.
“My sense is that our findings would likely prove relevant for cutting risk for diabetes, cancer and other chronic diseases as well.”