An Overview of Betaine Supplementation, Sports Performance, and Body Composition

Trimethylglycine (betaine) serves three major roles in mammal physiology: (1) a major osmolyte that accumulates in most tissues and assists in cell volume regulation, (2) a possible chaperone to stabilize native protein structure and prevent degradation under stressful conditions, and (3) a methyl donor in the metabolic process of transmethylation of homocysteine to methionine. Most ingested betaine is absorbed by the tissues, and tissue uptake is thought to be increased when cells are exposed to metabolic and osmotic stress. In several studies, supplementation with 2-3. g/day of betaine has been shown to enhance resistance training-based performance and improve body composition outcomes when associated with a resistance training program. Mechanistic research in humans is scarce; however, numerous animal studies suggest that the osmotic and methylation properties of betaine may enhance body composition and performance via the following mechanisms: stimulation of lypolysis and inhibition of lipogenic genes/enzymes, stimulation of autocrine/endocrine insulin-like growth factor 1 (IGF-1) release and insulin-receptor signaling, reduction of proinflammatory cytokines, and phosphorylation of proteins in the Akt-mTOR protein synthetic pathway. This chapter will present the studies that have investigated the effects of betaine supplementation on physical performance and body composition outcomes and explore the potential mechanisms underlying these effects in differing models.