Betaine (TMG)

Commonly used for

Muscle & StrengthHeart HealthAthletic Performance

What is it? / Overview

Betaine serves as a methyl donor in one-carbon metabolism helping convert homocysteine to methionine. It also functions as an osmolyte within muscle cells and may modestly improve power output and training performance in resistance-trained individuals.

How is it used? / Administration

Form: Anhydrous betaine (trimethylglycine)

Typical dose studied: 2.5–6 g/day (commonly 2.5 g twice daily)

Timing: With meals or 30–60 min before exercise

Evidence for athletic performance modest and more consistent for resistance training than endurance.

How well does it work? / Evidence

~ Moderate evidence

Who should avoid it?

Avoid with: Chronic kidney disease (Stage 3, 4, or 5) — NOT on dialysis; Dialysis (Hemodialysis or Peritoneal Dialysis)

Already taking it? Monitor homocysteine if used therapeutically.

Research & references

Cholewa JM et al. (2013). Betaine and body composition and performance. JISSN. Trepanowski JF et al. (2011). Chronic betaine supplementation and exercise performance. Journal of Strength and Conditioning Research. Schwab U et al. (2002). Betaine and homocysteine reduction. AJCN.