Creatine monohydrate for lean mass, strength, and bone density in postmenopausal women: a systematic review and meta-analysis.

抄録

Background: Menopause is accompanied by accelerated losses in muscle mass and strength and declining bone density. Whether creatine monohydrate benefits postmenopausal women are uncertain.Methods: We systematically reviewed randomized, placebo-controlled trials examining creatine supplementation, with or without resistance training (RT), in postmenopausal women. MEDLINE, Embase, Scopus, Web of Science, SPORTDiscus, and Cochrane CENTRAL were searched from 2000 to August 2025, supplemented by trial registries and reference-list screening. Eligible studies included postmenopausal women aged ≥40-45 years, intervention durations ≥6 weeks for primary analyses, and outcomes including DXA-derived lean mass, one-repetition maximum (1RM) strength, bone mineral density, physical function, and safety. Dual screening, duplicate extraction, and Cochrane RoB 2 assessment were performed. Random-effects meta-analysis used the Paule-Mandel estimator for τ² with Hartung-Knapp-Sidik-Jonkman adjustment. Heterogeneity (τ², I²), 95% prediction intervals, subgroup analyses by RT status, exploratory dose/duration meta-regression, small-study effects, and GRADE certainty were assessed.Results: Seven RCTs (n = 608 randomized; duration 12-104 weeks, median 38 weeks) enrolled postmenopausal women (mean age ≈ 62 y). Lean mass (k = 5; n = 338) favored creatine: mean difference (MD) + 0.37 kg (95% CI + 0.05 to + 0.69; I² = 25%; τ² = 0.01; 95% PI -0.10 to + 0.84). Leg-press 1RM (k = 3; n = 111) improved with creatine: MD + 7.5 kg (95% CI + 2.2 to + 12.8; I² = 0%). Benefits were evident when creatine ≥ 5 g·day⁻¹ was combined with RT; trials using ≤ 3 g·day⁻¹ without RT showed no measurable effect. Bone density was unchanged overall. Adverse events were mild and similar to placebo; renal indices were unchanged. Risk of bias was mostly "some concerns;" one large, preregistered, double-blind RCT was at low risk.Conclusions: In postmenopausal women, creatine, particularly ≥ 5 g·day⁻¹ with RT, yields small but meaningful gains in lean mass and strength without evidence of harm. Effects on bone density remain unclear.Registration: This review was not prospectively registered. De-identified data and supplementary materials were deposited on OSF after completion of the analysis (DOI: 10.17605/OSF.IO/BVTRZ).