B‐complex vitamin therapy for preventing cardiovascular events

Cardiovascular disease is the number one cause of death worldwide. The most common causes of its morbidity and mortality are ischaemic heart disease, stroke and congestive heart failure. Many people with cardiovascular diseases may be asymptomatic, and might have high risk for developing a myocardial infarction, angina pectoris, stroke (ischaemic, haemorrhagic or both). 'Emergent or new risk factors' for cardiovascular disease have been recently added to the established risk factors (diabetes mellitus, high blood pressure, active smoker, adverse blood lipid profile). One of these risk factors is an elevated circulating total homocysteine (tHcy) levels. Homocysteine is an amino acid, and its levels in blood are influenced by blood levels of B‐complex vitamins: cyanocobalamin (B12), folic acid (B9) and pyridoxine (B6). High tHcy levels are associated with an increased risk for atherosclerotic diseases. Hence, it has been suggested that B vitamins supplementation might reduce the risk of myocardial infarction, stroke, angina pectoris. Preventive strategies might include healthy people with low or high risk for developing cardiovascular disease (primary prevention) and people with an established cardiovascular disease (secondary prevention). In this review we included eight randomised controlled trials equivalent to 24,210 participants. We found no evidence that homocysteine‐lowering interventions, in the form of supplements of vitamins B6, B9 or B12 given alone or in combination, at any dosage compared with placebo or standard care, prevents myocardial infarction, stroke, or reduces total mortality in participants at risk or with established cardiovascular disease.