Betaine supplementation and plasma homocysteine in healthy volunteers

Elevated plasma total homocysteine concentrations are considered a risk factor for giving birth to a child with a neural tube defect1-2 and for cardiovascular disease.3 Epidemiological studies suggest that elevated homocysteine concentrations are an independent and graded risk factor for vascular disease, with no apparent threshold.3-6 Therefore, it appears that a decrease in plasma total homocysteine concentration in the lower range is still relevant. Homocysteine can be transsulfurated to cysteine using vitamin B6 as a cofactor. It can also be remethylated to methionine. This reaction either uses 5-methyltetrahydrofolate as a substrate in a vitamin B12–dependent reaction or it uses betaine. In humans, the folate-dependent remethylation takes place in all cells, whereas the betaine-dependent remethylation reaction is mainly confined to the liver.7 Supplementation with folic acid has been shown to decrease total plasma homocysteine concentrations in healthy volunteers