A number of studies over the past two decades have shown that religious people tend to be healthier. But a new study suggests that when it comes to heart disease and clogged arteries, attending religious services or having spiritual experiences may not protect against heart attacks and strokes.

This study suggests “there’s not a lot of extra burden or extra protection afforded by this particular aspect of people’s lives,” said Dr. Donald Lloyd-Jones, of the Feinberg School of Medicine, Northwestern University, Chicago, who led the study, published in the journal Circulation.

In their review of data from nearly 5,500 people who were part of another study, Lloyd-Jones and his colleagues -- one of whom, Matthew Feinstein, is a Northwestern medical student who suggested the research -- expected to see less risk for heart disease among those with more “religiosity.”

The authors defined religiosity as participation in religious activities, prayer or meditation, and spirituality, regardless of denomination. They did not report the religious faiths of study participants.

Over the course of 4 years, those in the study had 152 events related to heart disease or clogged arteries, including 9 deaths, 42 heart attacks, and 24 strokes. That rate of such events -- less than one percent per year -- was lower than in the general population, which the team expected because they excluded people who were already diagnosed with heart disease and related conditions.

However, neither the rate of heart disease events, nor the number of certain risk factors -- such as high cholesterol, diabetes, and high blood pressure -- differed among those who were more or less religious or spiritual. The only exceptions: Those who went to religious services, otherwise prayed or meditated, or were highly spiritual were more likely to be obese, and less likely to smoke.

Given that many religions discourage smoking tobacco, the smoking finding was not difficult to explain, Lloyd-Jones said, and is consistent with earlier studies.

The reasons for the obesity finding, which is similar to some previous studies but the opposite of others, are less clear. “We’re not sure whether it is that religious people are more likely to gain weight through activities they pursue, or maybe heavier people seek out religion as a result of stigmatization,” Lloyd-Jones said.

Dr. Harold G. Koenig, a professor of psychiatry and medicine at Duke University, Durham, North Carolina, said the obesity finding was not surprising, given that congregations and families often “fellowship” over meals.

Koenig, who has studied the potential connection between health and religion, was not involved in Lloyd-Jones’ work. He said the research is well-done, but it has a lot of limitations that make the meaning of the results unclear. For example, he said the low rate of heart attacks and other events could be a weakness of the study, because at small numbers, the likelihood of an effect is more difficult to tease out.

Koenig also noted that half of the people studied were either African American or Hispanic -- groups that, on average, have poorer access to health care than do whites and Asian Americans, who made up the rest of the study sample.

African Americans, on average, are also some of the most religious people in the world, Koenig said. “When you’ve got a population with this big a difference, struggling, and under stress, religion would have to overcome an enormous number of risk factors to have a significant effect.”

Lloyd-Jones agreed that the study is “not the final word. But it’s very interesting.”

Heart disease “is very complex,” Lloyd-Jones said. “It does not arise from a single source. Each of us brings our own mix of genes and environment.”

SOURCE: Circulation, online January 25, 2010.