title: Orally administered betaine has an acute and dose-dependent effect on serum betaine and plasma homocysteine concentrations in healthy humans.
abstract: Betaine, i.e., trimethylglycine, is linked to homocysteine metabolism. A 3-mo daily betaine supplementation decreased even normal plasma total homocysteine (tHcy) concentrations in humans. The pharmacokinetic characteristics and metabolism of betaine in humans have not been investigated in detail. The aim of this study was to assess the pharmacokinetics of orally administered betaine and its acute effect on plasma tHcy concentrations. Healthy volunteers (n = 10; 3 men, 7 women) with normal body weight (mean +/- SD, 69.5 +/- 17.0 kg), 40.8 +/- 12.4 y old, participated in the study. The betaine doses were 1, 3, and 6 g. The doses were mixed with 150 mL of orange juice and ingested after a 12-h overnight fast by each volunteer according to a randomized double-blind crossover design. Blood samples were drawn for 24 h and a 24-h urine collection was performed. Orally administered betaine had an immediate and dose-dependent effect on serum betaine concentration. Single doses of 3 and 6 g lowered plasma tHcy concentrations (P = 0.019 and P < 0.001, respectively), unlike the 1-g dose. After the highest dose, the concentrations remained low during the 24 h of monitoring. The change in plasma tHcy concentration was linearly associated with betaine dose (P = 0.006) and serum betaine concentration (R2 = 0.17, P = 0.025). The absorption and elimination of betaine were dose dependent. The urinary excretion of betaine seemed to increase with an increasing betaine dose, although a very small proportion of ingested betaine was excreted via urine. In conclusion, a single dose of orally administered betaine had an acute and dose-dependent effect on serum betaine concentration and resulted in lowered plasma tHcy concentrations within 2 h in healthy subjects.
authors.affiliation: Department of Clinical Nutrition, University of Kuopio, Finland. Ursula.Schwab@uku.fi
authors.forename: Ursula
authors.initials: U
authors.lastname: Schwab
authors.forename: Anneli
authors.initials: A
authors.lastname: Törrönen
authors.forename: Esa
authors.initials: E
authors.lastname: Meririnne
authors.forename: Markku
authors.initials: M
authors.lastname: Saarinen
authors.forename: Georg
authors.initials: G
authors.lastname: Alfthan
authors.forename: Antti
authors.initials: A
authors.lastname: Aro
authors.forename: Matti
authors.initials: M
authors.lastname: Uusitupa
mesh_terms: D000284:Administration, Oral; D000328:Adult; D019540:Area Under Curve; D001622:Betaine / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005765:Gastrointestinal Agents / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D006207:Half-Life; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007408:Intestinal Absorption; D008297:Male
chemical_list: D005765:Gastrointestinal Agents; D006710:Homocysteine; D001622:Betaine