Homocysteine lowering and cardiovascular events after acute myocardial infarction. Homocysteine lowering with folic acid and B vitamins in vascular disease. Lowering homocysteine in patients with ischemic stroke to prevent recurrent stroke, myocardial infarction, and death: the Vitamin Intervention for Stroke Prevention (VISP) randomized controlled trial. Mortality and cardiovascular events in patients treated with homocysteine-lowering B vitamins after coronary angiography: a randomized controlled trial. Effects of homocysteine-lowering with folic acid plus vitamin B12 vs placebo on mortality and major morbidity in myocardial infarction survivors: a randomized trial. B vitamins in patients with recent transient ischaemic attack or stroke in the VITAmins TO Prevent Stroke (VITATOPS) trial: a randomised, double-blind, parallel, placebo-controlled trial. Effect of homocysteine-lowering therapy on arterial elasticity and metabolic parameters in metformin-treated diabetic patients. Effects of short-term treatment with metformin on serum concentrations of homocysteine, folate and vitamin B12 in type 2 diabetes mellitus: a randomized, placebo-controlled trial. Folate administration reduces circulating homocysteine levels in NIDDM patients on long-term metformin treatment.
Homocysteine is a risk factor for cardiovascular disease. We evaluated the efficacy of homocysteine-lowering treatment with B vitamins for secondary prevention in patients who had had an acute myocardial infarction.
                The trial included 3749 men and women who had had an acute myocardial infarction within seven days before randomization. Patients were randomly assigned, in a two-by-two factorial design, to receive one of the following four daily treatments: 0.8 mg of folic acid, 0.4 mg of vitamin B12, and 40 mg of vitamin B6; 0.8 mg of folic acid and 0.4 mg of vitamin B12; 40 mg of vitamin B6; or placebo. The primary end point during a median follow-up of 40 months was a composite of recurrent myocardial infarction, stroke, and sudden death attributed to coronary artery disease.
                The mean total homocysteine level was lowered by 27 percent among patients given folic acid plus vitamin B12, but such treatment had no significant effect on the primary end point (risk ratio, 1.08; 95 percent confidence interval, 0.93 to 1.25; P=0.31). Also, treatment with vitamin B6 was not associated with any significant benefit with regard to the primary end point (relative risk of the primary end point, 1.14; 95 percent confidence interval, 0.98 to 1.32; P=0.09). In the group given folic acid, vitamin B12, and vitamin B6, there was a trend toward an increased risk (relative risk, 1.22; 95 percent confidence interval, 1.00 to 1.50; P=0.05).
                Treatment with B vitamins did not lower the risk of recurrent cardiovascular disease after acute myocardial infarction. A harmful effect from combined B vitamin treatment was suggested. Such treatment should therefore not be recommended. (ClinicalTrials.gov number, NCT00266487.).
                Copyright 2006 Massachusetts Medical Society. In observational studies, lower homocysteine levels are associated with lower rates of coronary heart disease and stroke. Folic acid and vitamins B6 and B12 lower homocysteine levels. We assessed whether supplementation reduced the risk of major cardiovascular events in patients with vascular disease.
                We randomly assigned 5522 patients 55 years of age or older who had vascular disease or diabetes to daily treatment either with the combination of 2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12 or with placebo for an average of five years. The primary outcome was a composite of death from cardiovascular causes, myocardial infarction, and stroke.
                Mean plasma homocysteine levels decreased by 2.4 micromol per liter (0.3 mg per liter) in the active-treatment group and increased by 0.8 micromol per liter (0.1 mg per liter) in the placebo group. Primary outcome events occurred in 519 patients (18.8 percent) assigned to active therapy and 547 (19.8 percent) assigned to placebo (relative risk, 0.95; 95 percent confidence interval, 0.84 to 1.07; P=0.41). As compared with placebo, active treatment did not significantly decrease the risk of death from cardiovascular causes (relative risk, 0.96; 95 percent confidence interval, 0.81 to 1.13), myocardial infarction (relative risk, 0.98; 95 percent confidence interval, 0.85 to 1.14), or any of the secondary outcomes. Fewer patients assigned to active treatment than to placebo had a stroke (relative risk, 0.75; 95 percent confidence interval, 0.59 to 0.97). More patients in the active-treatment group were hospitalized for unstable angina (relative risk, 1.24; 95 percent confidence interval, 1.04 to 1.49).
                Supplements combining folic acid and vitamins B6 and B12 did not reduce the risk of major cardiovascular events in patients with vascular disease. (ClinicalTrials.gov number, NCT00106886; Current Controlled Trials number, ISRCTN14017017.).
                Copyright 2006 Massachusetts Medical Society. In observational studies, elevated plasma total homocysteine levels have been positively associated with ischemic stroke risk. However the utility of homocysteine-lowering therapy to reduce that risk has not been confirmed by randomized trials.
                To determine whether high doses of folic acid, pyridoxine (vitamin B6), and cobalamin (vitamin B12), given to lower total homocysteine levels, reduce the risk of recurrent stroke over a 2-year period compared with low doses of these vitamins.
                Double-blind randomized controlled trial (September 1996-May 2003).
                3680 adults with nondisabling cerebral infarction at 56 university-affiliated hospitals, community hospitals, private neurology practices, and Veterans Affairs medical centers across the United States, Canada, and Scotland.
                All participants received best medical and surgical care plus a daily multivitamin containing the US Food and Drug Administration's reference daily intakes of other vitamins; patients were randomly assigned to receive once-daily doses of the high-dose formulation (n = 1827), containing 25 mg of pyridoxine, 0.4 mg of cobalamin, and 2.5 mg of folic acid; or the low-dose formulation (n = 1853), containing 200 microg of pyridoxine, 6 microg of cobalamin and 20 microg of folic acid.
                Recurrent cerebral infarction (primary outcome); coronary heart disease (CHD) events and death (secondary outcomes).
                Mean reduction of total homocysteine was 2 micromol/L greater in the high-dose group than in the low-dose group, but there was no treatment effect on any end point. The unadjusted risk ratio for any stroke, CHD event, or death was 1.0 (95% confidence interval [CI], 0.8-1.1), with chances of an event within 2 years of 18.0% in the high-dose group and 18.6% in the low-dose group. The risk of ischemic stroke within 2 years was 9.2% for the high-dose and 8.8% for the low-dose groups (risk ratio, 1.0; 95% CI, 0.8-1.3) (P =.80 by log-rank test of the primary hypothesis of difference in ischemic stroke between treatment groups). There was a persistent and graded association between baseline total homocysteine level and outcomes. A 3- micromol/L lower total homocysteine level was associated with a 10% lower risk of stroke (P =.05), a 26% lower risk of CHD events (P<.001), and a 16% lower risk of death (P =.001) in the low-dose group and a nonsignificantly lower risk in the high-dose group by 2% for stroke, 7% for CHD events, and 7% for death.
                In this trial, moderate reduction of total homocysteine after nondisabling cerebral infarction had no effect on vascular outcomes during the 2 years of follow-up. However, the consistent findings of an association of total homocysteine with vascular risk suggests that further exploration of the hypothesis is warranted and longer trials in different populations with elevated total homocysteine may be necessary. Observational studies have reported associations between circulating total homocysteine concentration and risk of cardiovascular disease. Oral administration of folic acid and vitamin B(12) can lower plasma total homocysteine levels.
                To assess the effect of treatment with folic acid and vitamin B(12) and the effect of treatment with vitamin B(6) as secondary prevention in patients with coronary artery disease or aortic valve stenosis.
                Randomized, double-blind controlled trial conducted in the 2 university hospitals in western Norway in 1999-2006. A total of 3096 adult participants undergoing coronary angiography (20.5% female; mean age, 61.7 years) were randomized. At baseline, 59.3% had double- or triple-vessel disease, 83.7% had stable angina pectoris, and 14.9% had acute coronary syndromes.
                Using a 2 x 2 factorial design, participants were randomly assigned to 1 of 4 groups receiving daily oral treatment with folic acid, 0.8 mg, plus vitamin B(12), 0.4 mg, plus vitamin B(6), 40 mg (n = 772); folic acid plus vitamin B(12) (n = 772); vitamin B(6) alone (n = 772); or placebo (n = 780).
                The primary end point was a composite of all-cause death, nonfatal acute myocardial infarction, acute hospitalization for unstable angina pectoris, and nonfatal thromboembolic stroke.
                Mean plasma total homocysteine concentration was reduced by 30% after 1 year of treatment in the groups receiving folic acid and vitamin B(12). The trial was terminated early because of concern among participants due to preliminary results from a contemporaneous Norwegian trial suggesting adverse effects from the intervention. During a median 38 months of follow-up, the primary end point was experienced by a total of 422 participants (13.7%): 219 participants (14.2%) receiving folic acid/vitamin B(12) vs 203 (13.1%) not receiving such treatment (hazard ratio, 1.09; 95% confidence interval, 0.90-1.32; P = .36) and 200 participants (13.0%) receiving vitamin B(6) vs 222 (14.3%) not receiving vitamin B(6) (hazard ratio, 0.90; 95% confidence interval, 0.74-1.09; P = .28).
                This trial did not find an effect of treatment with folic acid/vitamin B(12) or vitamin B(6) on total mortality or cardiovascular events. Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease.
                clinicaltrials.gov Identifier: NCT00354081. Blood homocysteine levels are positively associated with cardiovascular disease, but it is uncertain whether the association is causal.
                To assess the effects of reducing homocysteine levels with folic acid and vitamin B(12) on vascular and nonvascular outcomes.
                Double-blind randomized controlled trial of 12,064 survivors of myocardial infarction in secondary care hospitals in the United Kingdom between 1998 and 2008.
                2 mg folic acid plus 1 mg vitamin B(12) daily vs matching placebo.
                First major vascular event, defined as major coronary event (coronary death, myocardial infarction, or coronary revascularization), fatal or nonfatal stroke, or noncoronary revascularization.
                Allocation to the study vitamins reduced homocysteine by a mean of 3.8 micromol/L (28%). During 6.7 years of follow-up, major vascular events occurred in 1537 of 6033 participants (25.5%) allocated folic acid plus vitamin B(12) vs 1493 of 6031 participants (24.8%) allocated placebo (risk ratio [RR], 1.04; 95% confidence interval [CI], 0.97-1.12; P = .28). There were no apparent effects on major coronary events (vitamins, 1229 [20.4%], vs placebo, 1185 [19.6%]; RR, 1.05; 95% CI, 0.97-1.13), stroke (vitamins, 269 [4.5%], vs placebo, 265 [4.4%]; RR, 1.02; 95% CI, 0.86-1.21), or noncoronary revascularizations (vitamins, 178 [3.0%], vs placebo, 152 [2.5%]; RR, 1.18; 95% CI, 0.95-1.46). Nor were there significant differences in the numbers of deaths attributed to vascular causes (vitamins, 578 [9.6%], vs placebo, 559 [9.3%]) or nonvascular causes (vitamins, 405 [6.7%], vs placebo, 392 [6.5%]) or in the incidence of any cancer (vitamins, 678 [11.2%], vs placebo, 639 [10.6%]).
                Substantial long-term reductions in blood homocysteine levels with folic acid and vitamin B(12) supplementation did not have beneficial effects on vascular outcomes but were also not associated with adverse effects on cancer incidence.
                isrctn.org Identifier: ISRCTN74348595. Epidemiological studies suggest that raised plasma concentrations of total homocysteine might be a risk factor for major vascular events. Whether lowering total homocysteine with B vitamins prevents major vascular events in patients with previous stroke or transient ischaemic attack is unknown. We aimed to assess whether the addition of once-daily supplements of B vitamins to usual medical care would lower total homocysteine and reduce the combined incidence of non-fatal stroke, non-fatal myocardial infarction, and death attributable to vascular causes in patients with recent stroke or transient ischaemic attack of the brain or eye.
                In this randomised, double-blind, parallel, placebo-controlled trial, we assigned patients with recent stroke or transient ischaemic attack (within the past 7 months) from 123 medical centres in 20 countries to receive one tablet daily of placebo or B vitamins (2 mg folic acid, 25 mg vitamin B6, and 0.5 mg vitamin B12). Patients were randomly allocated by means of a central 24-h telephone service or an interactive website, and allocation was by use of random permuted blocks stratified by hospital. Participants, clinicians, carers, and investigators who assessed outcomes were masked to the assigned intervention. The primary endpoint was the composite of stroke, myocardial infarction, or vascular death. All patients randomly allocated to a group were included in the analysis of the primary endpoint. This trial is registered with ClinicalTrials.gov, NCT00097669, and Current Controlled Trials, ISRCTN74743444.
                Between Nov 19, 1998, and Dec 31, 2008, 8164 patients were randomly assigned to receive B vitamins (n=4089) or placebo (n=4075). Patients were followed up for a median duration of 3.4 years (IQR 2.0-5.5). 616 (15%) patients assigned to B vitamins and 678 (17%) assigned to placebo reached the primary endpoint (risk ratio [RR] 0.91, 95% CI 0.82 to 1.00, p=0.05; absolute risk reduction 1.56%, -0.01 to 3.16). There were no unexpected serious adverse reactions and no significant differences in common adverse effects between the treatment groups.
                Daily administration of folic acid, vitamin B6, and vitamin B12 to patients with recent stroke or transient ischaemic attack was safe but did not seem to be more effective than placebo in reducing the incidence of major vascular events. These results do not support the use of B vitamins to prevent recurrent stroke. The results of ongoing trials and an individual patient data meta-analysis will add statistical power and precision to present estimates of the effect of B vitamins.
                Australia National Health and Medical Research Council, UK Medical Research Council, Singapore Biomedical Research Council, Singapore National Medical Research Council, Australia National Heart Foundation, Royal Perth Hospital Medical Research Foundation, and Health Department of Western Australia.
                Copyright 2010 Elsevier Ltd. All rights reserved. Metformin may affect the risk of atherothrombotic disease. However, metformin increases levels of homocysteine (Hcy), considered an independent risk factor for atherosclerosis. We evaluate whether homocysteine-lowering has a beneficial effect on arterial elasticity and metabolic parameters in metformin-treated diabetic patients. In double-blind, placebo-controlled study, 60 diabetic patients treated with high dose of metformin were randomly assigned to receive daily oral supplementation with folate (1000 mcg), vitamins B12 (400 mcg) and B6 (10mg) (group 1) or placebo (group 2). Lipid profile, HbA1C, insulin, C-peptide, hs-CRP, vitamin B12, folic acid, homocysteine, endothelin, homeostasis model assessment-insulin resistance (HOMA-IR) were measured. Arterial elasticity was evaluated using pulse wave contour analysis (HDI CR 2000, Eagan, MN). The two groups were similar at baseline in terms of hemodynamic and arterial elasticity parameters. After a 4-month small artery elasticity index (SAEI) was significantly greater in patients who received Hcy-lowering agents than in the placebo group: 4.3+/-2.04 ml/mm Hg x 100 versus 3.2+/-1.1 ml/mm Hg x 100, p=0.01. Post-treatment vitamin B12 and folic acid levels were greater in group 1 versus group 2: 738.1+/-279.9 pg/ml versus 566.1+/-167.4 pg/ml, p=0.007 and 14.9+/-4.8 ng/ml versus 8.3+/-2.9 ng/ml, p<0.0001, respectively. Hcy level decreased significantly in the treatment group from 10.0+/-4.4 to 7.6+/-2.5 micromol/l, p=0.002 and did not change in placebo group (p=0.9). Hcy-lowering therapy improved small arterial elasticity in diabetic patients treated with high dose of metformin. The improvement was associated with a decrease in Hcy as well as an increase in folic acid and vitamin B12. These findings suggest that Hcy-lowering may have beneficial vascular effect in metformin-treated diabetic patients. Metformin is a key treatment option in type 2 diabetes. However, metformin may decrease vitamin B12 levels and increase levels of homocysteine, a cardiovascular risk factor. We investigated whether 16 weeks of treatment with metformin affects serum concentrations of homocysteine, folate and vitamin B12 in subjects with type 2 diabetes treated with insulin.
                Placebo-controlled, randomized trial. Measurements: at baseline and 16 weeks later.
                This trial was conducted in the outpatient clinics of three general hospitals in The Netherlands.
                A total of 745 patients with type 2 diabetes, treated with insulin and not known with a contraindication for the use of metformin, were approached; 390 gave informed consent and entered the study. Thirty-seven subjects dropped out (12 placebo and 25 metformin users).
                Addition of metformin or placebo to insulin therapy. PRIMARY OUTCOME PARAMETERS: Serum homocysteine, folate, vitamin B12, indices of glycaemic control and body weight.
                Amongst those who completed 16 weeks of treatment, metformin use, as compared with placebo, was associated with an increase in homocysteine of 4% (0.2 to 8; P=0.039) and with decreases in folate [-7% (-1.4 to -13); P=0.024] and vitamin B12 [-14% (-4.2 to -24); P<0.0001]. In addition, the increase in homocysteine could be explained by the decreases in folate and vitamin B12.
                In patients with type 2 diabetes, 16 weeks of treatment with metformin reduces levels of folate and vitamin B12, which results in a modest increase in homocysteine. The clinical significance of these findings remains to be investigated. Metformin treatment increases circulating homocysteine levels. We studied whether administration of folate reduces serum total homocysteine levels in patients on long-term metformin treatment.
                A prospective, randomized, double-blind, placebo-controlled study lasting for 12 weeks and taking place in a university hospital setting.
                Thirty patients treated with a metformin dose of at least 1000 mg day-1 for a minimum of 1 year were included. At baseline serum total homocysteine levels were within the reference range. One patient who withdrew and one who died were excluded from the statistical evaluation. Twenty-six of the remaining patients suffered from NIDDM, the other two from hyperlipidaemia.
                Patients were randomized into two groups at week 0. The folate group received 0.25 mg day-1 of folate in addition to 60 mg day-1 of Fe2+, while the placebo group received only 60 mg day-1 of Fe2+.
                Fasting homocysteine, cysteine, cysteinylglycine, vitamin B12 and folate were measured at week 0, 4 and 12. Changes from week 0 to week 4 and from week 0 to week 12 were calculated.
                Folate administration reduced serum levels of total homocysteine in the folate group as compared with the placebo group by 13.9% (P < 0.01) and 21.7% (P < 0.001) at week 4 and 12, respectively. In the folate group versus the placebo group serum levels of vitamin B12 increased by 9.9% (P = 0.010) and 9.6% (P = 0.043) while folate levels increased by 96.9 and 89.9% at week 4 and 12, respectively.
                The present study indicates that the homocysteine-increasing effect of metformin can be counteracted by folate administration.
This updated Cochrane review found no evidence to suggest that homocysteine-lowering interventions in the form of supplements of vitamins B6, B9 or B12 given alone or in combination should be used for preventing cardiovascular events. Furthermore, there is no evidence suggesting that homocysteine-lowering interventions are associated with an increased risk of cancer.