Association between serum iron and gallstones in US adults: a cross-sectional study

Gallstones are a common digestive disorder that threatens human health. Iron deficiency may be related to the formation of gallstones, but there is limited current epidemiological research. The objective of this study was to investigate the relationship between iron status and gallstones.

The datasets from the National Health and Nutrition Examination Survey (NHANES) 2017-2020 were used in a cross-sectional investigation. Gallstones were determined by using the 2007-2010 NHANES questionnaire. Multivariate linear regression models were used to examine the association between serum iron, serum ferritin and iron intake with the risk for gallstones. Subgroup analysis based on gender, age, race, and diabetes were performed. Fitted smoothing curves were used to describe the linear relationship.

The research involved 7847 participants aged 20 and above, among whom 845 were identified as having gallstones. Participants with higher serum iron levels tended to have a lower gallstones prevalence. A negative relationship between serum iron and gallstones prevalence was observed (OR = 0.979, 95% CI:0.965-0.992). The group with the highest serum iron tertile had a 23.7% lower risk of gallstones compared to the lowest tertile (OR = 0.763, 95% CI:0.628‒0.929). Gallstone prevalence was inversely correlated with iron intake in model 1. The negative association between serum iron and gallstones remained stable in stratifications, including gender, age, race, and diabetes.

Elevated serum iron was associated with a decreased prevalence of gallstones. However, to confirm the impact of long-term iron metabolism on gallstone formation, additional prospective research is necessary.