Betaine Anhydrous (Trimethylglycine)
An osmolyte and methyl donor (trimethylglycine) taken for modest strength and power benefits. Human trials are mixed but lean slightly positive for resistance-training outcomes. Also reliably lowers homocysteine, a separate, well-established metabolic effect.
01 Overview
Betaine (trimethylglycine) is found in beets and grains and functions both as a cellular osmolyte and as a methyl donor in homocysteine metabolism. Sports interest centres on proposed effects on cellular hydration, creatine synthesis and power output.
Resistance-training trials are inconsistent: several report small improvements in power, strength or body composition, while others find no effect. Its homocysteine-lowering action is well established and is the basis for an approved medical use in homocystinuria, but that is distinct from any ergogenic claim.
02 Mechanism
Acts as an intracellular osmolyte supporting cell hydration and as a methyl donor in homocysteine remethylation, potentially aiding creatine synthesis and protein metabolism.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 2.5–5 g/day | Oral | Typical ergogenic dose; often split into two servings. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Modest strength/power gainsSome resistance-training trials show small improvements in power and strength; others show none. | Small, inconsistent | Disputed | |
| Lowered plasma homocysteineReliably lowers homocysteine via remethylation; a well-established metabolic effect distinct from performance. | Dose-dependent reduction | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Gastrointestinal upsetNausea or diarrhoea at higher doses. | Mild | Occasional | Observational | |
| Body odour ('fishy' smell)High doses can produce a fishy body odour from trimethylamine formation, especially in susceptible individuals. | Mild | Rare | Observational |