Abstract
Background and aims: Betaine is an osmolyte that when catabolised decreases plasma total homocysteine. A betaine-rich meat has acute effects similar to a supplement, but the effects of a longer-term increase in dietary betaine intake need clarification. We compared the effects of two weeks of dietary and supplementary betaine on plasma betaine and homocysteine concentrations both fasting and after a methionine toad.
Methods and results: In a randomized crossover study, 8 healthy mates (22-36 y) consumed either a betaine-rich diet (similar to 800 mg/day) or a betaine supplement (0.5 g twice daily) for 14 days. Fasting blood samples were collected on day -5, -1 (pre-treatment) 0, 2, 6, 9, 13 (treatment), 14 and 18 (post-treatment). Post-methionine toad blood samples were collected on day -5, 0, 6 and 13, white 24 h urine samples were collected on day -5, 0, 6, 13 and 14. Plasma betaine, dimethylglycine, homocysteine and urine betaine, dimethylglycine and creatinine concentrations were measured. Plasma betaine concentrations significantly increased for both treatments compared to pre-treatment values (P < 0.001). Fasting homocysteine levels were minimally affected. Both treatments reduced post-methionine toad homocysteine and this effect tended to be greater following a betaine-rich diet (P = 0.108). Small increases in urinary betaine excretion were observed following both treatments (approximate to 1.5% of supplement; approximate to 1.3% of dietary betaine). Most was attributable to increased excretion of betaine as dimethylglycine.
Conclusions: Supplemental or dietary betaine similarly increase circulating betaine concentrations and attenuate the post-methionine toad rise in homocysteine concentrations. (c) 2009 Elsevier B.V. All rights reserved.