Many studies have found a correlation between marriage and good health. But two new studies have found something that apparently is at least as good for people and sometimes even better: cohabitation.

“A lot of the previous research has suggested that a marriage is the best thing since sliced bread,” says Jennifer Kohn, an assistant professor of economics and business at Drew University in Madison, N.J. Dr. Kohn and Susan Averett, a professor of economics at Lafayette University in Easton, Pa., took a closer look at that premise by studying data from a large annual survey in the U.K. that asks residents about their health.

In a study published in September in the Journal of Family and Economic Issues, the professors found that marriage was no better than cohabitation or other types of relationships for one’s health. In a second study using the same data, published online in April in the Journal of Health Economics, the researchers split up the population they were researching by age and gender, looking at men and women over and under the age of 45. They found that above age 45, people of both sexes who were living with someone but not married experienced a more positive effect on their health than those who were married.

The professors looked at data from more than 8,000 men and nearly 10,000 women, with a mean age of 46. Individuals were asked about chronic conditions, accidents, mental and emotional health, and problems with vision, hearing, the heart and diabetes, among other things. By using the U.K. data, the professors were able to erase the effects of disparities in health insurance that would have been found in a U.S. sample.

To try to focus on the causal link between health and relationship status, rather than a correlation that could be at least partially coincidental, the professors designed their analysis to eliminate as much as possible the so-called selection effect—the possibility that people who are healthier to begin with are more likely to get married or live together. They also aimed to eliminate other factors that could influence both health and relationship status independently, so that only the direct link between the two would emerge.

“The existing literature has speculated on the mechanism that drives the correlation between marriage and health,” says Dr. Kohn. “Is marriage associated with good health because of the strength of the bonds uniquely associated with marriage that reflect a greater commitment and in some cases at least are harder to dissolve? Or is marriage associated with good health because of the presence of another presumably caring person in the household?”

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