If heredity puts you at higher risk for a heart attack, maintaining a healthy lifestyle can bring that risk down, below the risk faced by some people whose genes would normally protect them from heart disease, according to an analysis of more than 55,000 people.
“We were a little surprised by how much you could offset your inherited risk by adhering to a healthy lifestyle,” said Sekar Kathiresan, chief author of the new study, published online simultaneously by the New England Journal of Medicine.
The 20 per cent of the population with the highest genetic risk had a 5.1 per cent chance of having a heart attack over 10 years if they practised a healthy lifestyle.
That was lower than the 5.8 per cent likelihood among people with the lowest genetic risk but who had an unfavorable lifestyle.
If you adhere to a healthy lifestyle, you can reduce your risk by maybe 50 per cent
But the study also confirms that genes play a key role in the risk of heart attack, regardless of lifestyle.
Among people who practised heart-healthy habits, the odds of a heart attack among people with a low genetic risk was 3.1 per cent over 10 years compared with 5.1 per cent when their genetic risk was high.
Among people who were obese, did not exercise, smoked, and did not eat a healthy diet, the heart attack rate when the genetic risk was low was almost double (5.8 per cent per decade) the baseline risk of 3.1 per cent. It jumped to 10.7 per cent when their genetic risk was high.
Because people cannot alter their genetic profile and their only option is to change their lifestyle, the good news from the study is that making those lifestyle changes can have a real impact, said Kathiresan, director at the Centre for Human Genetic Research at Massachusetts General Hospital in Boston.
“Many physicians and patients assume if you have a strong inherited risk, you’re destined to have a heart attack; you can’t change the hand that’s dealt to you in terms of genetics,” he said. “But if you adhere to a healthy lifestyle, you can reduce your risk by maybe 50 per cent.”
More than 55,000 people from four databases were included in the study. To rank their inherited risk of a heart attack, the researchers tested them for 50 genetic variants linked to a higher risk of cardiovascular disease.
People who met three or four of the healthy criteria were classified as living a favourable lifestyle. Those who met one or none were classified as having an unfavourable lifestyle.
“This is the first study to look at the interplay of both genetics and lifestyle, and how much you could offset your genetic risk with an optimal lifestyle,” said Kathiresan.
It has been known since the late 1930s that the risk of heart disease is partly inherited. In recent years, genetic studies have refined the risks.
The degree to which lifestyle changes, including quitting smoking, can reduce that risk has remained uncertain.
Among risk factors that people could alter, the researchers found that not smoking cut the overall heart attack risk by 44 per cent, not being obese reduced it by 33 per cent, getting regular physical activity dropped it by 16 per cent and maintaining a healthy diet made a heart attack nine per cent less likely.