Betaine (trimethylglycine) is a nutrient found in a variety of plants, animals and microorganisms . It plays an important role in several aspects of human health and nutrition and studies show that diets high in betaine decrease disease risk [1,3-5]. It is a compound that is involved in the metabolism of choline and homocysteine. In the recent years, betaine has gotten much attention for its potential role as an ergogenic aid and has become a common ingredient in various pre-workout supplements.
Rich natural sources of betaine (trimethylglycine) :
- bran (1,330 mg per 100 g)
- wheat germ (1,241 mg per 100 g)
- spinach (600 mg per 100 g)
- beets (250 mg per 100 g)
- wheat bread (200 mg per 100 g)
- shellfish (218 mg per 100 g)
Ergogenic Effects of Betaine Supplementation
A research article published in Journal of the International Society of Sports Nutrition  examined the effects of two drink solutions on cycling sprint performance on college-aged males (n = 9) and females (n = 7). A commercial carbohydrate-electrolyte beverage as the placebo and the same carbohydrate-electrolyte beverage with 2.5 g of betaine (minimum purity is 99%; BetaPower™) as the experimental drink.
They analyzed average and maximum peak and mean power. As shown in Figure 1 below compared to baseline, betaine group increased average peak power (6.4%), maximum peak power (5.7%), average mean power (5.4%), and maximum mean power (4.4%) for all subjects combined. Compared to placebo, betaine group significantly increased average peak power (3.4%), maximum peak power max (3.8%), average mean power (3.3%), and maximum mean power (3.5%) for all subjects combined. There were no changes in lean mass.
Figure 1 – Individual cycle runs power comparison for all subjects. A: peak power; B: mean power. * p < 0.05 compared to corresponding baseline value. # p < 0.05 compared to corresponding placebo value. W = watts, BL = baseline, PL = placebo, Be = betaine.
Hoffman and associates  found that two-weeks of betaine supplementation in active, college males appeared to improve muscle endurance of the squat exercise and increase the quality of repetitions performed. Elaine C. Lee et al.  investigated the ergogenic effects of betaine supplementation on strength and power performance on 12 male subjects that underwent a 14-day experimental trial separated by a 14-day washout period, in a balanced, randomized, double-blind, repeated measures, crossover design. The conclusion of the study was that betaine supplementation increases power, force and maintenance of these measures. Supplementation with betaine has also been reported to elevate levels of blood nitric oxide almost 3-fold . This means that by increasing muscle blood flow during exercise and increasing the delivery of nutrients and extraction of waste products betaine could improve performance. Betaine has also been reported to affect muscle signalling proteins . It may enhance muscle protein synthesis by reducing homocysteine and homocysteine thiolactone which inhibits Akt-phosphorylation and subsequent mechanistic target of rapamycin (mTOR) activation by reducing insulin receptor substrate-1 activation .
On the other hand, a study by Trepanowski and colleagues  reported a moderate increase in total repetitions and volume load in the bench press exercise (but not leg exercise) with 14-day betaine (2.5 g/day) supplementation, without other beneficial effects on performance.
Betaine has been shown to increase serum growth hormone, insulin-like growth factor 1, and insulin in animals; these compounds are likely to promote protein synthesis by stimulating the mTOR pathway .
Other Possibly Beneficial Uses of Betaine
Betaine has also been marketed as a supplement designed to promote heart health as well as a weight loss. There are two studies that have probably contributed to these beliefs. Ursula Schwab et al.  have shown that betaine may reduce homocysteine levels (a marker of risk to heart disease) without affecting body composition and another study in chickens by Garcia Neto et al.  has shown that supplementing with betaine can affect liver metabolism, fat metabolism, and fat deposition. However, studies in humans report no effect of betaine supplementation on fat mass [6,9].
There seems to be very little evidence in human models that support the role of betaine as a supplement for weight loss, thus it is not recommended for supplementation.
Side Effects and Precautions
Although betaine has been shown to lower homocysteine, its ingestion has been associated with dose-dependent increase in low-density-lipoprotein (LDL) cholesterol [11,9]. A possible mechanism of betaine on LDL cholesterol formation is that betaine administration spares the use of choline, making more choline available for phosphatidylcholine biosynthesis in the liver which increases VLDL formation . However, a more recent epidemiological review reported that long-term betaine (and choline) supplementation prevents cardiovascular disease mortality by decreasing inflammation and other risk factors .
(Other common names: Trimethylglycine hydrochloride, Trimethylglycine HCL, Betaine Chlorhydrate, Betaine HCl, TMG, Trimethyl Glycine, Trimethylglycine)
- Craig SAS: Betane in human nutrition. Am J Clin Nutr 2004, 80:539-549.
- Zeisel SH, Mar MH, Howe JC, Holden JM: Concentrations of choline-containing compounds and Trimethylglycine in common foods. J Nutr 2003, 133:1302-1307.
- Konstantinova SV, Tell GS, Vollset SE, Nygard O, Bleie O, Ueland PM: Divergent associations of plasma choline and Trimethylglycine with components of metabolic syndrome in middle age and elderly men and women. J Nutr 2008, 138:914-920.
- Cho E, Willett WC, Colditz GA, Fuchs CS, Wu K, Chan AT, Zeisel SH, Giovannucci EL: Dietary choline and Trimethylglycine and the risk of distal colorectal adenoma in women. J Natl Cancer Inst 2007, 99:1224-1231.
- Shaw GM, Carmichael SL, Yang W, Selvin S, Schaffer DM: Periconceptional dietary intake of choline and Trimethylglycineand neural tube defects in offspring. Am J Epidemiol 2004, 160:102-109.
- Pryor JL, Craig SAS, Swensen T: Effect of Trimethylglycine supplementation on cycling sprint performance. Journal of the International Society of Sports Nutrition 2012, 9:12.
- Hoffman, Jay R., et al. “Effect of betine supplementation on power performance and fatigue.” Journal of the International Society of Sports Nutrition 6.1 (2009): 1-10.
- Lee, Elaine C., et al. “Ergogenic effects of betine supplementation on strength and power performance.” J Int Soc Sports Nutr 7 (2010): 27.
- Schwab, Ursula, et al. “Trimethylglycine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects.” The American journal of clinical nutrition 76.5 (2002): 961-967.
- Garcia Neto M, Pesti GM, Bakalli RI: Influence of dietary protein level on the broiler chicken’s response to methionine and Trimethylglycine supplements. Poult Sci 2000, 79(10):1478-84.
- Zeisel, Steven H. “Beatine supplementation and blood lipids: Fact or artifact?.”Nutrition reviews 64.2 (2006): 77-79.
- Rajaie, Somayeh, and Ahmad Esmaillzadeh. “Dietary choline and beaaine intakes and risk of cardiovascular diseases: review of epidemiological evidence.”ARYA atherosclerosis 7.2 (2011): 78.
- Trepanowski, John F., et al. “The effects of chronic Trimethylglycine supplementation on exercise performance, skeletal muscle oxygen saturation and associated biochemical parameters in resistance trained men.” The Journal of Strength & Conditioning Research 25.12 (2011): 3461-3471.
- Iqbal, Omer, et al. “TMG induced release of tissue factor pathway inhibitor and nitric oxide: implications in the management of cardiovascular disease.” The FASEB Journal20.4 (2006): A655-A655.
- Ismaeel, Ahmed. “Effects of betaine supplementation on muscle strength and power: a systematic review.” The Journal of Strength & Conditioning Research 31.8 (2017): 2338-2346.
- Li, Yin, et al. “Homocysteine upregulates resistin production from adipocytes in vivo and in vitro.” Diabetes 57.4 (2008): 817-827.