Beta-hydroxy-beta-methylbutyrate in functional food ingredients: An overview of biosynthesis, metabolic mechanisms and applications

β-Hydroxy-β-methylbutyrate (HMB) is a metabolite of the essential amino acid leucine, which can be produced naturally in mammals and is also found in trace amounts in citrus fruits and fish. Studies have shown that HMB plays an important role in maintaining human health by improving muscle health and inhibiting muscle catabolism. This review summarises the synthesis and metabolism of HMB and discusses its potential use as a nutrient, highlighting and analysing the importance of HMB supplementation for athletes' physical recovery and the treatment of muscular dystrophy-related diseases between 2019 and 2025. This study will help us to deepen our understanding of the application of HMB as a dietary supplement for the treatment of different diseases, providing the latest insights into its sustainability.