Betaine is a cofactor in various methylation reactions.
Betaine works with choline, vitamin B12, and also S-adenosylmethionine(SAMe), a derivative of the amino acid methionine, from which homocysteine is synthesised. It reduces homocysteine levels by re-methylating homocysteine to produce methionine.
As a supplement, betaine is available in the form of the hydrochloride and as such contains 23% hydrochloric acid. It has been used as a digestive aid to treat people with achlorhydria and to reduce high levels of homocysteine. Whether it can reduce near normal levels of homocysteine is open to question.
Betaine has been reported to play a role in reducing plasma homocysteine levels, which may reduce the risk of heart disease. A study in 15 healthy men and women aged 18–35 years showed that betaine 6g daily for 3 weeks reduced plasma homocysteine concentration after 2 weeks by 0.9µmol/L and after 3 weeks by 0.6µmol/L. However, the extent of the decrease was much smaller than that in patients with homocystinuria and appears to be smaller than that established by interventions with folic acid. An RCT in 42 obese subjects found that betaine supplementation (6g daily for 12 weeks) decreased plasma homocysteine concentration by 8.76±1.63µmol/L at the start of the study and 7.93±1.52µmol/L at the end of the study. However, there is insufﬁcient evidence to recommend betaine supplements for the prevention of CHD.
Betaine should be avoided in patients with peptic ulcer.
Pregnancy and breast-feeding
No problems have been reported, but there have not been sufﬁcient studies to guarantee the safety of betaine in pregnancy and breastfeeding.
Betaine may cause gastrointestinal irritation.
Betaine is available in the form of tablets and capsules.
The dose is not established. Dietary supplements provide 250–500mg in each dose.
(excerpted from) Dietary Supplements, Third Edition, by Pamela Mason, BSc, MSc, PhD, MRPharmS, published by Pharmaceutical Press, London, 2007.