Myths About Betaine
Betaine is sold as a strength booster, a fat burner and even "the new creatine". Our editorial team examines the most common myths and sets out what the research actually supports.
Betaine: a quick introduction
Betaine, chemically trimethylglycine (TMG), is a compound found naturally in sugar beet, spinach, wheat bran and shellfish. In the body it acts as a methyl donor, helping to convert the amino acid homocysteine into methionine, and as an osmolyte that helps cells maintain their water balance under stress.
In sports nutrition, betaine anhydrous is sold as a stand-alone powder and as an ingredient in pre-workouts. It has been studied for strength, power and body composition, with results that are interesting but less consistent than marketing suggests.
Its popularity has produced a number of myths. Some exaggerate its benefits, others confuse it with entirely different products. This article goes through the most common ones.
The aim is not to dismiss betaine but to place it accurately among the many supplements competing for an athlete's budget.
Myth 1: betaine HCl and betaine anhydrous are the same thing
This is probably the most widespread confusion. Betaine hydrochloride (betaine HCl) is sold as a digestive aid, marketed to increase stomach acidity. Betaine anhydrous is the form studied in sports and homocysteine research.
| Feature | Betaine anhydrous (TMG) | Betaine HCl |
|---|---|---|
| Main use | Sports supplement, homocysteine metabolism | Marketed as a digestive aid |
| Research in sport | Several controlled trials | Essentially none |
| Effect on stomach acid | None intended | Releases hydrochloric acid |
| Key caution | May raise cholesterol at higher doses | Can irritate the stomach; not for people with ulcers or reflux |
Taking betaine HCl in the hope of improving strength makes little sense and may cause heartburn or stomach irritation. Check the label carefully.
A prescription form of betaine anhydrous is used under specialist care to treat homocystinuria, a rare inherited disorder. This medical use should not be confused with sports supplementation.
Myth 2: betaine works like creatine
Betaine is sometimes described as "the new creatine". There is a biochemical link: betaine can contribute methyl groups used in the body's own creatine synthesis. But this does not mean it produces the same effects.
Creatine is one of the most thoroughly researched supplements, with consistent benefits for repeated high-intensity efforts and muscle gain when combined with training. Betaine's evidence base is far smaller.
Some trials, such as those by Lee and colleagues and by Cholewa and colleagues, reported improvements in power output, training volume or body composition with around 2.5 g a day. Other studies found no meaningful difference from placebo.
A reasonable view is that betaine may offer a modest benefit for some people, while creatine remains the better-supported first choice.
Myth 3: betaine is a fat burner
Marketing sometimes presents betaine as a supplement that "melts fat". A study by Cholewa and colleagues in trained men reported improved body composition with betaine during a resistance training programme, which fuelled these claims.
However, a controlled trial by Schwab and colleagues in overweight people on a diet found that betaine did not affect body weight, body composition or resting energy expenditure. Results therefore depend on context, and betaine is not a fat-loss agent in its own right.
Any body composition benefit appears, at best, to be small and to require consistent training and nutrition. It should not be expected to compensate for an energy surplus.
Supplements marketed for fat loss sometimes combine betaine with high-dose stimulants. The risks of those products come mainly from the stimulants, not from betaine.
Myth 4: betaine is completely risk-free
Betaine is generally well tolerated, but "natural" does not mean free of side effects. Some people experience digestive discomfort, nausea or diarrhoea, especially with larger doses on an empty stomach.
A meta-analysis by Zawieja and colleagues found that betaine supplementation moderately increased total cholesterol, with effects more evident at higher doses. For people with raised cholesterol or cardiovascular risk, this is worth discussing with a doctor.
- Studies in sport have typically used around 2.5 g a day, often split into two doses with food.
- The EU authorised health claim on homocysteine metabolism is linked to an intake of at least 1.5 g a day.
- People with kidney disease, high cholesterol or those who are pregnant or breastfeeding should seek advice first.
- Anyone with a diagnosed metabolic disorder must follow specialist guidance.
Athletes subject to testing should use batch-tested products, as multi-ingredient formulas can be contaminated with prohibited substances.
Editorial conclusions
Betaine is a genuine nutrient with a clearly established role in homocysteine metabolism, recognised in an authorised EU health claim. Its performance and body composition effects are possible but modest and inconsistent.
It is not the same as betaine HCl, not a replacement for creatine and not a fat burner. At higher doses it may raise cholesterol, which matters for people with cardiovascular risk.
Used sensibly, it is a low-risk option for curious athletes, but not a priority purchase.
You may also want to read our articles on creatine monohydrate, homocysteine and B vitamins, and what to look for in a pre-workout.
References
- Cholewa JM, Wyszczelska-Rokiel M, Glowacki R, et al. Effects of betaine on body composition, performance, and homocysteine thiolactone. J Int Soc Sports Nutr. 2013;10(1):39.
- Lee EC, Maresh CM, Kraemer WJ, et al. Ergogenic effects of betaine supplementation on strength and power performance. J Int Soc Sports Nutr. 2010;7:27.
- Schwab U, Törrönen A, Toppinen L, et al. Betaine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects. Am J Clin Nutr. 2002;76(5):961–967.
- Olthof MR, van Vliet T, Boelsma E, Verhoef P. Low dose betaine supplementation leads to immediate and long term lowering of plasma homocysteine in healthy men and women. J Nutr. 2003;133(12):4135–4138.
- Zawieja EE, Zawieja B, Chmurzynska A. Betaine supplementation moderately increases total cholesterol levels: a systematic review and meta-analysis. J Diet Suppl. 2021;18(1):105–117.
- Cholewa JM, Guimarães-Ferreira L, Zanchi NE. Effects of betaine on performance and body composition: a review of recent findings and potential mechanisms. Amino Acids. 2014;46(8):1785–1793.
