Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

BACKGROUND: Remethylation of homocysteine to methionine can occur through either the folate-dependent methionine synthase pathway or the betaine-dependent betaine-homocysteine methyltransferase pathway. The relevance of betaine as a determinant of fasting total homocysteine (tHcy) is not known, nor is it known how the 2 remethylation pathways are interrelated. OBJECTIVE: The objectives of the study were to examine the relation between plasma betaine concentration and fasting plasma tHcy concentrations and to assess the effect of folic acid supplementation on betaine concentrations in healthy subjects. DESIGN: A double-blind randomized trial of 6 incremental daily doses of folic acid (50-800 microg/d) or placebo was carried out in 308 Dutch men and postmenopausal women (aged 50-75 y). Fasted blood concentrations of tHcy, betaine, choline, dimethylglycine, and folate were measured at baseline and after 12 wk of vitamin supplementation. RESULTS: Concentrations of tHcy were inversely related to the betaine concentration (r = -0.17, P < 0.01), and the association was independent of age, sex, and serum concentrations of folate, creatinine, and cobalamin. Folic acid supplementation increased betaine concentration in a dose-dependent manner (P for trend = 0.018); the maximum increase (15%) was obtained at daily doses of 400-800 microg/d. CONCLUSIONS: The plasma betaine concentration is a significant determinant of fasting tHcy concentrations in healthy humans. Folic acid supplementation increases the betaine concentration, which indicates that the 2 remethylation pathways are interrelated.

Original publication

DOI

10.1093/ajcn/81.6.1378

Type

Journal article

Journal

Am J Clin Nutr

Publication Date

06/2005

Volume

81

Pages

1378 - 1382

Keywords

Administration, Oral, Aged, Betaine, Choline, Dietary Supplements, Dose-Response Relationship, Drug, Double-Blind Method, Fasting, Female, Folic Acid, Hematinics, Homocysteine, Humans, Male, Methionine, Methylation, Middle Aged