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

Key summary points Aim This systematic review and meta-analysis aim to explore the effects of HMB on body composition in older adults. Finding Available evidence suggests that HMB supplementation in older adults can promote increased muscle mass but may not be effective in reducing fat mass. The results of subgroup analysis indicated that exercise might limit the effect of HMB supplementation in older people, but this did not indicate that exercise did not help the muscle mass and function of older people. Message This study not only illustrates that HMB supplementation is an effective way to improve sarcopenia in older people but also highlights the urgent need to develop rational exercise programs to meet the needs of older people. 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