Betaine – more muscle, less fat?

Bodybuilders who took 2.5 g of betaine daily for 6 weeks improved body composition. Sports scientists from Coastal Carolina University have published the results of their experiment in the International Society of Sports Nutrition. 1 But how does betaine affect hypertrophy and fat loss? Well, we don’t know yet. The reason most scientists in nutrition and sports supplementation are interested in betaine is the role they play in converting the potentially dangerous amino acid homocysteine into a harmless compound.

Homocysteine is an intermediate amino acid discovered in 1932 that is formed during methionine metabolism. According to current scientific knowledge, it is an independent risk factor for ischemic heart disease, cerebrovascular disease (e.g. ischemic stroke), peripheral arteries and venous thrombosis. Excessive methionine supply or disorders of its transformation lead to an increase in homocysteine concentration in the cells from which it passes into the blood and is then excreted in the urine. Under normal conditions, homocysteine concentration is moderate – its formation and breakdown are balanced.

Betaine chemical structure
Betaine chemical structure

methionine => demethylation => homocysteine

The norm for homocysteine is between 4 and 14 mol/L.


  • has an impact on the occurrence of e.g. ischemic stroke,
  • causes oxidative stress, e.g. by affecting lipid metabolism (the process of vascular endothelial dysfunction),
  • may cause dysfunctions in the genetic code of DNA and RNA (hypo- and hypermethylation),
  • lowers adenosine => increases platelet aggregation => thromboembolic risk,
  • reduces the synthesis of nitric oxide (NO) through the influence of asymmetric dimethylarginine arising in hyperhomocysteinemia,
  • increases thromboxane synthesis, while thromboxane causes contraction of e.g. damaged blood vessels and platelet aggregation,
  • causes LDL deposition within the coronary vessels (S-homocysteilation process), most likely has an effect on the atherosclerotic process,
  • disrupts coagulation processes,
  • has an impact on the development of atherosclerosis of renal vessels in hypertension,
  • probably contributes to diseases involving dementia (e.g. Alzheimer’s disease).

Homocysteine is further converted to homocysteine thiolactone, which inhibits muscle protein synthesis, probably mainly by disrupting insulin receptor function (insulin is the main anabolic hormone that is associated with muscle growth and reversal of catabolic processes, which is why it has found such widespread use in doping). Bodybuilders provide large amounts of animal protein, which means they also deliver large amounts of methionine. Perhaps, according to the researchers, this is what causes them to produce so much homocysteine thiolactone. Perhaps, that’s why betaine supplementation accelerates muscle growth (inhibits the effect of the homocysteine metabolite).

What did the study look like?

Twenty-three people were selected in terms of training experience and percentage of body fat. They were assigned to the placebo (12 people) or betaine (11 people) group. 2.5 g betaine or placebo was administered daily. Both groups completed six weeks of exercise, and they were three two-week cycles.

Squeeze and squat training volumes were recorded, and changes in training volume were evaluated in each microcycle. Urine was collected at the beginning of the study (BL), after 2, 4 and 6 weeks and the concentration of homocysteine thiolactone (HCTL) was determined. Patients were examined before and after 6 weeks of treatment. The cross-sectional area of the shoulder and thigh (CSA), i.e. hypertrophy, was estimated by measuring circumference and skin fold. Density was estimated using a caliper (skin fold measurement) and this data was used to estimate the% BF content, body fat (FM) and lean body mass (LBM). The increase in performance was assessed by means of vertical jump (VJ), bench press – 1 maximum repetition and squat per 1 maximum repetition.


At the end of the sixth week, bodybuilders who took betaine lost several percent of their body fat. In addition, betaine supplementation also resulted in a significant increase in lean body mass. Bodybuilders in the betaine group gained more muscle, which was found, for example, by measuring shoulder circumference. In the placebo group, the increase was negligible (0.1 cm3). Similarly, the thigh circumference was greater in the betaine group compared to the placebo group.