Gallstones are hardened deposits of digestive fluid that form in the gallbladder. They are a common problem; more than 3 million cases of gallstones are seen over the course of a year, according to the National Institutes of Health.

Researchers from Tulane University in New Orleans reviewed the results of seven U.S. studies including more than 800,000 people and 51,000 cases of coronary artery disease.

Six percent of women and 3 percent of men had a history of gallstones. These people tended to be older, were more often smokers or regular aspirin users, were less physically active, had a higher body mass index and more often had a history of high blood pressure, diabetes, or high cholesterol.

After adjusting for the common heart disease risk factors, as well as age, lifestyle, and other factors, researchers found that people with a history of gallstones had a 23 percent higher risk of heart disease compared to others.

This study, which appears in Arteriosclerosis, Thrombosis, and Vascular Biology, was observational, which means it doesn’t say gallstones cause coronary heart disease, but it does suggest that they talk to their doctors and discuss this, along with their other risk factors.