Low-fat diets and testosterone in men: Systematic review and meta-analysis of intervention studies

Background Higher endogenous testosterone levels are associated with reduced chronic disease risk and mortality. Since the mid-20th century, there have been significant changes in dietary patterns, and men’s testosterone levels have declined in western countries. Cross-sectional studies show inconsistent associations between fat intake and testosterone in men. Methods Studies eligible for inclusion were intervention studies, with minimal confounding variables, comparing the effect of low-fat vs high-fat diets on men’s sex hormones. 9 databases were searched from their inception to October 2020, yielding 6 eligible studies, with a total of 206 participants. Random effects meta-analyses were performed using Cochrane’s Review Manager software. Cochrane’s risk of bias tool was used for quality assessment. Results There were significant decreases in sex hormones on low-fat vs high-fat diets. Standardised mean differences with 95 % confidence intervals (CI) for outcomes were: total testosterone [−0.38 (95 % CI −0.75 to −0.01) P = 0.04]; free testosterone [−0.37 (95 % CI −0.63 to −0.11) P = 0.005]; urinary testosterone [−0.38 (CI 95 % −0.66 to −0.09) P = 0.009]; and dihydrotestosterone [−0.3 (CI 95 % −0.56 to −0.03) P = 0.03]. There were no significant differences for luteinising hormone or sex hormone binding globulin. Subgroup analysis for total testosterone, European and North American men, showed a stronger effect [−0.52 (95 % CI −0.75 to −0.3) P