Postoperative Monacolin K Supplementation and Lipid Profile After Sleeve Gastrectomy: A Retrospective Comparative Analysis in Women

Background: Sleeve gastrectomy (SG) reliably reduces weight and triglycerides, but LDL-C responses are variable. In this retrospective observational study, we evaluated whether adjunctive monacolin K (red yeast rice; 3 mg/day) improves early lipid modulation after SG. Methods: In this single-center retrospective study of women only, 149 patients undergoing SG within the national KOS-BAR program were analyzed in four groups: controls without supplementation (CG, n = 62) and three supplementation cohorts receiving monacolin K for 6 months (G1 early (from week 1; n = 46), G2 delayed (months 3–9; n = 10), and G3 delayed (months 6–12; n = 31)). Outcomes included total cholesterol (TC), LDL-C, HDL, and triglycerides (TG). Missing data were imputed; mixed models for repeated measures assessed longitudinal changes. Results: From baseline to 6 months, LDL-C-C increased in the control group (CG; +21.9 mg/dL) and decreased in G1 (mean change: −11.1 mg/dL), with a significant group-by-time interaction (p < 0.001). HDL-C increased in both CG and G1, whereas triglyceride levels decreased more markedly in G1 than in CG (−36.2 vs. −19.6 mg/dL). Total cholesterol decreased in G1 (−13.4 mg/dL) and in G2 at 9 months (−22.5 mg/dL). Conclusions: In the early supplementation group, LDL-C-C levels decreased over the first 6 months after SG, whereas an increase was observed in the control group, which had significantly lower baseline LDL-C concentrations. In women undergoing SG, early postoperative monacolin K supplementation was associated with LDL-C stabilization and enhanced lipid optimization without impeding weight-loss benefits. Delayed initiation yields partial improvements, especially for TG and HDL-C. These observations underscore the need for prospective, sex-stratified studies with appropriate baseline adjustments to clarify the association between monacolin K use and postoperative lipid trajectories after SG.