Short people have an increased risk of heart disease that may be partly due to their genes, a new study suggests.
Researchers analyzed information from more than 65,000 people with coronary artery disease and 128,000 people who did not have this disease. Coronary artery disease is a type of heart disease in which plaque builds up in the arteries that supply blood to the heart.
The researchers looked at 180 genetic markers known to affect people's height, to see if they were also linked with coronary artery disease.
The study found that, for every 2.5-inch increase in a person's height, the risk of coronary artery disease decreased by 13.5 percent, on average. For example, the risk of coronary artery disease would be about 32 percent higher for a 5-foot-tall person compared to a person who is 5 feet 6 inches, the researchers said.
Although many lifestyle factors, such as smoking, affect people's risk of developing coronary heart disease, the findings emphasize that "the causes of this common disease are very complex," said study researcher Dr. Nilesh Samani, a professor of cardiology at the University of Leicester in the United Kingdom.
The study also found that people who had more of the height-increasing genetic markers were at lower risk for coronary artery disease. People who had the most height-increasing genetic markers were 26 percent less likely to have coronary artery disease than those with the fewest height-increasing genetic markers. [Where Is Heart Disease Risk the Highest and Lowest? (Maps)]
The link between height and coronary artery disease was found only in men, and not women. However, there were fewer women than men in the study, which may have affected the ability of the study to detect a significant finding in women.
A number of studies have linked short stature with heart disease risk, but it was not known whether this link was a direct link or whether it was due to other factors, such as poor nutrition during childhood that could affect both a person's height and his or her heart disease risk.
"By using the power of very-large-scale genetic studies, this research is the first to show that the known association between increased height and a lower risk of coronary heart disease is at least in part due to genetics, rather than purely down to nutrition or lifestyle factors," Jeremy Pearson, associate medical director of the British Heart Foundation, which funded the study, said in a statement.
Dr. Andrew Freeman, director of clinical cardiology at National Jewish Health in Denver, said the findings agree with earlier research showing that people at the high and low extremes of height are at increased risk for early death. For example, a 2012 study found that shorter people are more likely to die from heart problems or stroke.
But that doesn't mean that people who are short should be worried about the findings.
"Just because you're shorter, or you have genes to be shorter, doesn't necessarily mean you're going to have coronary artery disease," said Freeman, who was not involved in the study.
While there's not much people can do about their genes, "the goal is to take the genes you have been given and put them in the best possible environment, Freeman said. Habits such as eating a more plant-based diet, exercising regularly and not leading a sedentary lifestyle "can have a huge impact," on reducing heart disease risk, Freeman said.
The study also found a link between the height genetic markers and people's cholesterol and fat levels, which are risk factors for coronary artery disease. This suggests that the link between genetically determined short height and coronary artery disease is due, in part, to higher cholesterol and fat levels in shorter people.
However, these risk factors could only explain part of the link, meaning that other factors likely play a role. There could be a shared biological process that determines both height and the development of heart disease, the researchers said.
Because the study found an association, not a cause-and-effect relationship, it does not prove that the genes that determine height also cause heart disease.
Freeman noted that because the study included mostly people from Western countries, there may be lifestyle factors that affect the findings that the researchers weren't able to take into account.
The study is published online today (April 8) in the New England Journal of Medicine.