Reduced Systemic Levels of Bile Acids in Individuals with Coronary Artery Disease: Insights from a Systematic Review.

Bile acids (BAs) play a key role in cholesterol metabolism and inflammation. Although altered circulating BA profiles have been reported in cardiometabolic disorders such as type 2 diabetes (T2D) and obesity, their relationship with coronary artery disease (CAD) remains poorly understood. We conducted a systematic review of human studies searching PubMed, Web of Science, and Scopus, assessing circulating BA concentrations in adults with angiographically confirmed CAD compared to non-CAD (NCAD) controls. Risk of bias was evaluated using the Newcastle-Ottawa Scale. From 2782 records, four observational studies met the inclusion criteria. All reported lower circulating BA concentrations in individuals with CAD compared to NCAD controls, with differences ranging from -5.4% to -52.8%. Two studies found a significant inverse association between BA levels and CAD. One study reported lower BA levels only in CAD in men, while another found the reduction more pronounced in individuals with T2D. However, all studies were observational, and most lacked adjustment for confounders such as sex and age. Current evidence suggests that lower circulating BA levels are linked to CAD and may be influenced by sex and T2D status. Further mechanistic and prospective studies are needed to clarify the relevance and directionality of this association.