Newswise — CLEVELAND––Gay men are more than twice as likely to develop inflammatory bowel disease (IBD) than heterosexual men when both populations engage in high-risk sexual activity, according to new research from the Digestive Health Research Institute at Case Western Reserve University and University Hospitals Cleveland Medical Center (UH)

The study was published this month in the peer-reviewed medical journal Gut.

“To our knowledge, this is the first large population-based study that demonstrates a higher prevalence of IBD in men who engage in high-risk same-sex sexual activity,” said Emad Mansoor, study lead author and assistant professor at the Case Western Reserve School of Medicine and UH. “Our study is expected to open a new field of research into gastrointestinal inflammatory conditions.”

“Studying the cause of IBD in this underrepresented patient population in comparison to other patient groups,” said Fabio Cominelli, corresponding study author, professor at the School of Medicine and chief scientific officer at UH, “will allow us to further investigate the cause of disease development in Crohn’s disease and ulcerative colitis patients and develop personalized precision medicine and treatment strategies, while also reducing stigma.”

The study’s impact is significant, as more than 7.1% of the United States population identifies as LGBTQIA+, an increase from 5.6% in 2020, according to Gallup.

The findings

The team evaluated self-reported data from patients treated at 58 healthcare organizations in the U.S. between 2002 and 2022.

The data showed that in patients with a diagnosis of high-risk same-sex sexual activity, 0.8% were diagnosed with Crohn’s disease and 1.26% with ulcerative colitis. These findings were compared to men who engage in high-risk heterosexual activity, of which, 0.49% had Crohn’s disease and 0.52% had ulcerative colitis.

High-risk sexual activity as defined in this study includes sexual contact without barrier protection as well as having multiple sexual partners.

The team also further analyzed the data in relation to Crohn’s disease and found men who engaged in high-risk same-sex sexual activity were more likely to have peri-anal disease including peri-anal abscess, rectal abscess and stricturing disease of the colon or small intestine. Among those with severe manifestations of ulcerative colitis, men who engaged in high-risk same-sex sexual activity were more likely to undergo partial colectomy.

The findings will be further evaluated by the team–including investigation into the potential role of the gut microbiome–during a long-term study that allows investigators to track participants over time.

Continuing research with NIH funding

The team will continue its research to better understand if and how LGBTQIA+ individuals are more susceptible to gastrointestinal disorders through funding awarded this year for the Cleveland Digestive Diseases Research Core Center (DDRCC). 

The center recently received a $100,000 supplementary grant from the National Institutes of Health (NIH). It will allow the researchers to significantly expand the number of LGBTQIA+ patients included in the DDRCC’s biorepository core, which collects plasma, tissue and stool samples and gut microbiome analyses.

“This supplementary grant is an addition to our $1 million NIH grant funding that is running 2020 through 2025,” Cominelli said. “We are in the process of opening a new clinic dedicated to LGBTQ+ patients with the goal of improving access to healthcare. Our goal is to improve patient access and develop new therapies for gastrointestinal conditions.”



Case Western Reserve University is one of the country's leading private research institutions. Located in Cleveland, we offer a unique combination of forward-thinking educational opportunities in an inspiring cultural setting. Our leading-edge faculty engage in teaching and research in a collaborative, hands-on environment. Our nationally recognized programs include arts and sciences, dental medicine, engineering, law, management, medicine, nursing and social work. About 5,800 undergraduate and 6,300 graduate students comprise our student body. Visit to see how Case Western Reserve thinks beyond the possible.

About University Hospitals / Cleveland, Ohio Founded in 1866, University Hospitals serves the needs of patients through an integrated network of more than 20 hospitals (including five joint ventures), more than 50 health centers and outpatient facilities, and over 200 physician offices in 16 counties throughout northern Ohio. The system’s flagship quaternary care, academic medical center, University Hospitals Cleveland Medical Center, is affiliated with Case Western Reserve University School of Medicine, Northeast Ohio Medical University, Oxford University and the Technion Israel Institute of Technology. The main campus also includes the UH Rainbow Babies & Children's Hospital, ranked among the top children’s hospitals in the nation; UH MacDonald Women's Hospital, Ohio's only hospital for women; and UH Seidman Cancer Center, part of the NCI-designated Case Comprehensive Cancer Center. UH is home to some of the most prestigious clinical and research programs in the nation, with more than 3,000 active clinical trials and research studies underway. UH Cleveland Medical Center is perennially among the highest performers in national ranking surveys, including “America’s Best Hospitals” from U.S. News & World Report. UH is also home to 19 Clinical Care Delivery and Research Institutes. UH is one of the largest employers in Northeast Ohio with more than 30,000 employees. Follow UH on LinkedIn, Facebook and Twitter. For more information, visit

Journal Link: Gut