Betaine gives bodybuilders more muscle and less fat
Bodybuilders who take a daily 2.5 g betaine [structural formula shown here] for six weeks will improve their body composition. Sports scientists from Coastal Carolina University draw this conclusion in the Journal of the International Society of Sports Nutrition. But how betaine stimulates muscle build-up and fat breakdown at the same time remains a mystery.
The reason most nutritional scientists are interested in betaine has to do with the role it plays in converting the potentially dangerous amino acid homocysteine [structural formula shown here] into a harmless compound. The figure below shows this process.
Homocysteine is further converted into homocysteine thiolactone [formula shown here], which inhibits the synthesis of muscle proteins, probably mainly by interfering with the functioning of the insulin receptor. [[J Mol Endocrinol. 2005 Feb;34(1):119-26.]
Bodybuilders eat large amounts of animal protein, which means they ingest large amounts of methionine. Maybe, the researchers reasoned, that's what causes them produce so much homocysteine thiolactone that betaine supplementation speeds up their muscle growth.
The researchers tested their hypothesis by doing an experiment with two dozen experienced recreational bodybuilders – men aged between 18 and 35. All of the men followed the same intensive training schedule for six weeks. Half of them were given a placebo; the other half took 2.5 g betaine every day.
At the end of the six weeks the bodybuilders who had taken betaine had lost a couple of percent fat mass. On top of that, the betaine supplementation also resulted in a significant increase in lean body mass. The scans that the researchers did showed that the bodybuilders in the betaine group had also gained more muscle in their arms.
The amount of homocysteine thiolactone [HCTL] was lower in the betaine users in week 2, week 4 and week 6 of the study in comparison to the amount they had at the start of the study [BL].
The researchers observed no significant effects of betaine on maximal strength or power.
Despite the effects they observed on the concentration of homocysteine thiolactone, the researchers don't think they have uncovered the mechanism through which betaine improves muscle mass and breaks down fat. At the start of the experiment the participants' concentration of homocysteine thiolactone was 0.028 nanomoles per millilitre. That's low. The range is 0.011 to 0.473 nanomoles per millilitre. "Based on the small differences in HCTL changes, betaine supplementation may have impacted body composition via other mechanisms", the researchers write.
One possibility the researchers suggest is that betaine works as a natural synthol. "Because betaine is a powerful osmolyte, the increases in lean mass may have been due to cellular swelling without an appreciable increase in myofibril protein accretion."
The research was financed by DuPont, a manufacturer of betaine. A DuPont Nutrition & Health employee participated in the study.
J Int Soc Sports Nutr. 2013 Aug 22;10(1):39.
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