Changes in basal and postmethionine load concentrations of total homocysteine and cystathionine after B vitamin intervention.
نویسندگان
چکیده
BACKGROUND Vitamin B-6 is necessary for the metabolism of homocysteine and is often used in combination with folic acid and vitamin B-12 in clinical trials that investigate whether the lowering of plasma total homocysteine (tHcy) can prevent vascular disease. OBJECTIVE We compared the effects of vitamin B-6 with the effects of folic acid and vitamin B-12, as used in the Western Norway B-vitamin Intervention Trial (WENBIT), on basal and postmethionine load (PML) tHcy and cystathionine concentrations. DESIGN Ninety patients with suspected coronary artery disease were randomly assigned to 1 of 4 groups to receive daily oral treatment with 1) 0.8 mg folic acid, 0.4 mg vitamin B-12, and 40 mg vitamin B-6 (group A); 2) 0.8 mg folic acid and 0.4 mg vitamin B-12 (group B); 3) 40 mg vitamin B-6 (group C); or 4) placebo (group D). For the first 2 wk, groups A and B received additional folic acid (5 mg/d). A methionine-loading test was performed at baseline and after 3 mo. RESULTS Treatment with folic acid and vitamin B-12 caused a rapid and significant lowering of basal (31%) and PML tHcy concentrations (22%), with no effect on cystathionine. Vitamin B-6 did not change basal tHcy and had a significant but limited effect on PML tHcy concentrations. However, vitamin B-6 treatment markedly lowered basal and PML cystathionine by 31% and 42%, respectively. CONCLUSION The folic acid and vitamin B-12 combination applied in WENBIT provides rapid, substantial, and long-term tHcy-lowering effects, whereas the effect of vitamin B-6 on tHcy was relatively small and confined to PML tHcy. However, vitamin B-6 treatment caused a marked reduction in plasma cystathionine. Cystathionine could be a useful marker for assessment of the vitamin B-6 effect and should, together with tHcy, be related to clinical outcome in ongoing trials.
منابع مشابه
Betaine as a determinant of postmethionine load total plasma homocysteine before and after B-vitamin supplementation.
OBJECTIVE Betaine is a substrate in the betaine-homocysteine methyltransferase reaction, converting homocysteine to methionine. There are only sparse data on plasma betaine as a determinant of the plasma total homocysteine (tHcy) concentration. METHODS AND RESULTS Ninety patients undergoing coronary angiography were randomized into 4 groups administered oral: (1) folic acid (0.8 mg), vitamin ...
متن کاملThe effect of a subnormal vitamin B-6 status on homocysteine metabolism.
Homocysteine, an atherogenic amino acid, is either remethylated to methionine or metabolized to cysteine by the transsulfuration pathway. The biochemical conversion of homocysteine to cysteine is dependent upon two consecutive, vitamin B-6-dependent reactions. To study the effect of a selective vitamin B-6 deficiency on transsulfuration, we performed oral methionine load tests on 22 vitamin B-6...
متن کاملResponse of homocysteine, cystathionine, and methylmalonic acid to vitamin treatment in dialysis patients.
BACKGROUND Hyperhomocysteinemia is observed in >80% of hemodialysis patients and is considered a risk factor for cardiovascular disease. Vitamin treatment lowers total homocysteine (tHcy) concentrations in plasma and may therefore reduce the associated risk. Current treatment strategies have not achieved normalization of tHcy in the majority of dialysis patients. METHODS We administered folic...
متن کاملDietary and supplementary betaine: acute effects on plasma betaine and homocysteine concentrations under standard and postmethionine load conditions in healthy male subjects.
BACKGROUND Betaine comes from the diet and from choline, and it is associated with vascular disease in some patient groups. Betaine supplementation lowers plasma total homocysteine. OBJECTIVE We compared the acute effects of dietary and supplementary betaine and choline on plasma betaine and homocysteine under standard conditions and after a methionine load. DESIGN In a randomized crossover...
متن کاملBetaine and folate status as cooperative determinants of plasma homocysteine in humans.
OBJECTIVE Two published studies have demonstrated that betaine in the circulation is a determinant of plasma total homocysteine, but none had sufficient power to investigate the possible effect modification by folate status. METHODS AND RESULTS We measured homocysteine, betaine, folate, vitamin B(6), and related compounds in serum/plasma from 500 healthy men and women aged 34 to 69 years befo...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The American journal of clinical nutrition
دوره 80 3 شماره
صفحات -
تاریخ انتشار 2004