Performance supplements

Betaine

Some training studies suggest body-composition changes, but maximal-strength findings are weaker and lipid effects deserve attention.

Small randomized training trials plus lipid experiments

Betaine molecular structure — Structure reference · C5H11NO2

Practical use

Applying the explained evidence

Where it fits: Some training studies suggest body-composition changes, but maximal-strength findings are weaker and lipid effects deserve attention.
Put the information into practice: The useful question is whether adding betaine improves outcomes beyond the same training program. Improvements shared by both groups should not be credited to the supplement.
Connect evidence to your training: Specify the outcome you want to improve and a repeatable way to measure it. Check whether the study participants, activity and product match the claim; avoid crediting one supplement for changes made alongside several training or diet changes.
Keep this limit in view: The female trial did not find a significant treatment interaction for maximum strength.

Six-week trained-men trial

Eight-week untrained-women trial

Overview

Betaine, or trimethylglycine, participates in methyl-group metabolism. Changes in homocysteine-related markers, body composition and cardiovascular risk are not interchangeable outcomes.

Risks and limitations

Randomized supplementation studies have reported higher LDL cholesterol and triglycerides. A favorable homocysteine result therefore does not establish net cardiovascular benefit. The size of the effect depends on the tested exposure and population.

How to read this

The useful question is whether adding betaine improves outcomes beyond the same training program. Improvements shared by both groups should not be credited to the supplement.

Research explained

Trained men

Who was studied

23 men, 11 active and 12 placebo; six-week periodized resistance training.

What was found

Bench-press work capacity improved in selected training blocks and body-composition estimates favored betaine. No significant between-group advantage in bench or squat maximum strength was found.

What it cannot establish

Skinfold/girth estimates are not direct muscle imaging; small sample, several outcomes and short duration.

Read the original study

Untrained women

Who was studied

23 collegiate women; eight weeks of resistance training.

Fat-mass reduction: betaine: 2 kg
Fat-mass reduction: placebo: 0.8 kg

What was found

Fat mass fell 2.0 kg with betaine versus 0.8 kg with placebo. Strength, lean mass and muscle-thickness improvements did not significantly differ between groups.

What it cannot establish

Beginners improved substantially with training; the fat-mass result is not evidence of extra muscle gain in experienced men.

Read the original study

Lipid tradeoff

Who was studied

Pooled data from randomized nutrient experiments; 151 participants contributed to three betaine studies.

What was found

A six-week higher-exposure condition increased LDL by 0.36 mmol/L versus placebo, with 95% CI 0.25–0.46. Triglycerides also increased.

What it cannot establish

Different exposures from the training trials; these are biomarkers, not observed heart-attack rates.

Read the original study

Work capacity is not maximal strength

More completed training volume in selected blocks can coexist with no clear extra one-repetition maximum gain.

Supporting source

Training explains shared gains

Both female groups gained strength and lean mass. Only the between-group contrast isolates the added intervention.

Supporting source

One favorable marker is insufficient

Lower homocysteine-related measures cannot erase a less favorable lipid response or establish fewer clinical events.

Supporting source

Measurement influences interpretation

The male study estimated body composition with skinfolds; the female study used different tools. Their kilogram estimates are not identical measurements.

Supporting source