Betaine (Trimethylglycine) for Strength and Power: What the Research Really Shows
Betaine (trimethylglycine), naturally found in beets, spinach, and quinoa, is a common ingredient in pre-workout formulas marketed for strength and power. It acts as both a cellular osmolyte and a methyl donor — but a 2025 systematic review adds important nuance to how strong that evidence base really is.
What the newest systematic review found
- A 2025 systematic review published in Physical Activity and Nutrition analyzed five studies (101 total participants) on betaine and endurance exercise performance.
- Only two of the five studies showed significant improvements: one found a VO2max improvement in professional soccer players after 98 days of supplementation, and another found increased mean power late in a Wingate anaerobic test.
- The remaining three studies found no significant effect on time-to-exhaustion, time-to-completion, or peak power.
- All included studies were rated at high risk of bias, mainly due to poor intervention reporting — the authors explicitly flagged the "paucity of evidence" for betaine's ergogenic potential.
What about strength and power specifically?
- Separate meta-analytic work on strength outcomes reports a moderate effect size (~0.47) for maximal strength, concentrated mainly in the lower body (~0.49 SMD).
- Vertical jump performance improved modestly (~0.36 SMD) once a low-quality outlier study was excluded.
- No significant benefit was found for upper body strength, cycling sprint power, or muscular endurance — the effect appears specific to certain lower-body power/strength metrics, not a global performance booster.
Practical guidance
- Typical studied dose: ~2.5 g/day, taken for at least 1–2 weeks, with more consistent effects reported after 4–6 weeks.
- Betaine is most plausible as a support for lower-body strength and jump-type power, not as a broad endurance or upper-body strength enhancer.
- Given the small number of studies and high risk of bias, treat betaine as a low-cost, low-risk "maybe" rather than a proven ergogenic aid — it is reasonably safe, but the evidence does not yet justify strong claims.
The bottom line
Betaine's evidence base is real but thin: consistent enough to explain its popularity, inconsistent enough that most reviewers call for better-quality trials before drawing firm conclusions. If you already have a solid training program, adequate protein, and creatine dialed in, betaine is a reasonable low-priority addition — not a foundational supplement. This article is for general educational purposes and is not a substitute for individualized medical advice.
Helpful products
- Betaine anhydrous powder — an unflavored, stackable option for testing a 2.5 g/day protocol.
- Milligram-accurate scale — useful for measuring consistent supplement doses.
Source: Physical Activity and Nutrition (Perreras & Kim, systematic review, 2025)
[article_related]
