Effects of oral administration of β-hydroxy β-methylbutyrate on lean body mass in older adults: a systematic review and meta-analysis.

OBJECTIVE: Beta-hydroxy beta-methylbutyrate (HMB), a metabolite of leucine, is currently widely used in athletes to increase muscle mass and strength and has also been used as a nutritional supplement in recent years to maintain muscle mass in muscular atrophic diseases of older people. However, the effects of HMB supplementation on muscle mass, muscle strength, and physical function in older people remain controversial. The purpose of this review was to explore the effects of HMB on body composition in older adults.

METHODS: The PubMed, EMBASE and Cochrane Central Register of Controlled Trials databases were searched to obtain the randomized controlled trials needed as a basis for systematic review and meta-analysis.

RESULT: A total of 9 studies (448 participants) were eventually found eligible. The pooled results showed that HMB supplementation significantly increased fat-free mass in older people compared with the control group (effect size: 0.37; 95% Cl 0.16, 0.58; Z value = 3.47, P = 0.001; Fixed-effect model). But it had no effect on fat mass (effect size: - 0.04 95% CI - 0.26, 0.18; Z value = 0.36, P = 0.716, fixed-effect model). Subgroup analysis of HMB supplementation alone showed a significant improvement in fat-free mass in older people (effect size: 0.59; 95% CI 0.32, 0.87; Z = 4.24, P < 0.001; fixed-effect model), whereas HMB supplementation combined with exercise intervention showed no additional fat-free mass change (effect size: 0.06; 95% CI - 0.26, 0.38; Z = 0.38, P = 0.705; Fixed-effect model).

CONCLUSION: HMB supplementation is beneficial for improving body composition in older people. However, the effect of HMB supplementation combined with exercise therapy to improve muscle mass is not obvious. Exercise programs need to be designed according to the different physical health of older people.