A new study suggests that abandoning religion may have a negative impact on some people's health.

The study found that 40 per cent of those who said they practise a religion with strict social, moral and physical guidelines consider themselves to be in excellent health.

As religious adherence decreased, the percentage of those describing themselves as in excellent health also decreased.

About 25 per cent of those who switched to a more liberal religious group said they were in excellent health, and the figure dropped to 20 per cent for people who quit religion all together.

The study was conducted by Christopher Scheitle, a senior research assistant in sociology at Penn State University, and is published in the latest issue of the Journal of Health and Social Behaviour.

He said: "Strict groups typically require members to abstain from unhealthy behaviours, such as alcohol and tobacco use.

"These groups also create both formal and informal support structures to promote positive health.

"The social bonds of belonging to the group might be another factor for better health."

In the study, The Church of Jesus Christ of Latter-Day Saints (Mormon) and Jehovah’s Witnesses were defined as “strict” religions. Both of the exclusive groups have strict guidelines for how members should live, including no alcohol or tobacco consumption.

The two religious groups are not embraced by theological Christian conservatives, with the first group claiming the Book of Mormon as a holy text and the second rejecting the doctrine of the Trinity, among other major differences.

In his report, Scheitle suggested the decline in health could be a result of resuming unhealthy behaviours prohibited by a particular faith, losing the formal and informal support structures that promote positive health, or suffering from increased stress.

“You could lose your friends or your family becomes upset when you leave, leading to psychological stress and negative health outcomes,” he said.

The sociologist said more studies need to be conducted to determine the correlation between leaving a religion and health. He emphasised that the study does not show that leaving a religion directly results in bad health.

Results of Scheitle’s study based on the examination of 30,523 cases collected from 1972 through 2006 in the General Social Surveys conducted by Opinion National Research Center.

Out of this data pool, the researcher narrowed the number down to 423 people in strict religious group, 96 people who switched religion, and 54 who are no longer affiliated with any religion.