The effect of B-vitamins on the prevention and treatment of cardiovascular diseases: a systematic review and meta-analysis.

CONTEXT: Previous research evaluating the effects in B-vitamins on the prevention and treatment of cardiovascular disease (CVD) has substantial limitations and lacks recently published large prospective studies; hence, conducting an updated meta-analysis is needed. OBJECTIVE: We investigated the association between vitamin B status and human CVD development in order to provide more specific advice about vitamin B intake for those at risk of CVD. DATA SOURCES: Relevant articles were identified by JSTOR, PubMed, and ProQuest databases. DATA EXTRACTION: Key words used to identify the studies included the different combinations of B-vitamins, folate, folic acid, vitamin B6, vitamin B12, homocysteine, cardiovascular disease, stroke, coronary disease, myocardial infarction, and cerebrovascular and transient ischemic attack. The database search was supplemented by hand-searching of reference lists of selected articles. DATA ANALYSIS: Pooled estimates were calculated from the mean differences using a random-effects model. RESULTS: Supplementation with folic acid was reported to have a clinical benefit of significantly reducing carotid intima-media thickness. Higher intakes of folic acid, vitamin B6, and vitamin B12 were generally associated with a lower risk of CVD in the general population, except in those without normal renal function and those with unstable angina or past non-ST-elevation myocardial infarction. CONCLUSION: Vitamin B supplementation resulted in the greatest cardiovascular benefit in those with normal renal function and without unstable angina or non-ST-elevation myocardial infarction recently. Factors such as age, gender, and genetic polymorphisms contribute to varying effects.