Betaine is the amino acid glycine, but with 3 methyl groups attached to it. Its job is to donate the extra methyl groups for a variety of biochemical processes in the body.
One reaction is by donating to the amino acid homocysteine to create methionine. Methionine plays a significant role in muscle protein synthesis and muscle strength.
Clinical studies have shown betaine supplementation improved athletic endurance in multiple sports. That's muscle growth, strength, and endurance all in one! We stack betaine with creatine because they work in synergy.