THURSDAY, Dec. 15 (HealthDay News) -- Gay men who live in states where same-sex marriage is legal are healthier, have less stress, make fewer doctor visits and have lower health-care costs, a new study finds.

It included more than 1,200 patients at a large Massachusetts health clinic that provides services for gay men and other sexual minorities.

During the 12 months after the 2003 legalization of same-sex marriage in Massachusetts, there was a significant decrease in medical care visits, mental health visits and mental health-care costs among gay and bisexual men, compared to the 12 months before the law changed.

This led to a 13 percent reduction in health-care visits and a 14 percent reduction in health-care costs. The health benefits were similar for single gay men and those with partners.

No reduction was seen in HIV-related health visits by HIV-positive men, which suggests that those in need of HIV/AIDS care continued to use needed health-care services, the researchers said.

The study was published online Dec. 15 in the American Journal of Public Health.

"These findings suggest that marriage equality may produce broad public health benefits by reducing the occurrence of stress-related health conditions in gay and bisexual men," lead author Mark Hatzenbuehler, a Robert Wood Johnson Foundation Health & Society Scholar at Columbia University's Mailman School of Public Health, said in a foundation news release.

Lesbians weren't included in the study because there were too few who visit the clinic.

Previous research has shown that not having the legal right to marry can have a stressful effect on gays, lesbians and bisexuals, according to the release.

"This research makes important contributions to a growing body of evidence on the social, economic and health benefits of marriage equality," Hatzenbuehler said.

More information

The U.S. Centers for Disease Control and Prevention has more about lesbian, gay, bisexual and transgender health.