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Betaine (TMG, trimethylglycine)

A methyl-donor from beetroot with modest but repeatable strength gains — plus a homocysteine-lowering bonus.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsAmino acidsPerformanceMethylation

Betaine (trimethylglycine) is derived from the amino acid glycine and found in beets. It has two distinct roles: a performance aid and a methylation nutrient.

Key takeaways

  • Betaine (TMG) is a methyl donor derived from glycine, concentrated in beetroot.
  • Around 2.5 g/day for ≥1 week may modestly enhance strength and power.1
  • It also helps recycle homocysteine to methionine, lowering homocysteine levels.
  • Well tolerated at typical doses.

What it is

Betaine anhydrous (trimethylglycine, TMG) donates methyl groups and acts as an osmolyte in cells. It is both a sports supplement and a nutrient involved in methylation.

The evidence

Several trials suggest ~2.5 g/day for at least a week can improve muscular strength and power, especially lower-body strength, though not every study agrees.1 Separately, betaine reliably lowers homocysteine.

Dose & how to use

2.5 g/day (often split), taken consistently. Whole-food sources include beets, spinach and wheat bran.

Safety & who benefits

Safe at supplement doses; very high intakes can raise blood lipids in some people. Of interest to strength and power athletes and for homocysteine management.

Bottom line: a low-cost, modestly effective strength aid that doubles as a methylation nutrient — worth a look for lifters.

References

Adult research summary for education, not a prescription. These are food supplements, not treatments for disease.

  1. Cholewa JM, et al. Effects of betaine on body composition, performance, and homocysteine. J Int Soc Sports Nutr 2013. pmc.ncbi.nlm.nih.gov

This article summarises nutrition and exercise science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.