The Western Norway B-vitamin intervention trial (WENBIT) failed to find protective effects associated with homocysteine-lowering intervention with folates, or with vitamin B6.
The study included 3090 patients with established heart disease, mainly stable angina and coronary artery disease. Their mean age was 61.8 years. They were randomised into four groups: placebo; vitamin B6 alone; folic acid plus vitamin B12; and a combination of folic acid with vitamins B12 and B6. Mean follow-up was 38 months.
Homocysteine levels were lowered by 28% in the groups receiving folate, and remained unchanged in the non-folate group. However, lower levels did not appear to have a protective effect. In all, 422 patients experienced at least one event (all cause mortality, non-fatal myocardial infarction, unstable angina or nonfatal thromboembolic stroke).
Ebbing said that WENBIT confirms the findings of similar trials completed in the last few years: “At this time, vitamin B supplementation is not justified as secondary prevention for coronary artery disease.”
It is too early to give up research on homocysteine, she said, which is a marker for increased risk, but may not be a causal factor. “These are very complex mechanisms,” Ebbing added. “There are lots of vitamins and cofactors in the system. If you put large doses of folate and vitamin B12into one part of this big system, it might upset the balance in some way.”