NEW YORK (Reuters Health) – In patients with diabetic nephropathy, high doses of B vitamins accelerate kidney dysfunction and increase the rate of myocardial infarction (MI) and strokes, according to a Canadian study.

B vitamins are used to lower high plasma levels of homocysteine, which is linked to an elevated risk for diabetic nephropathy and vascular diseases, the authors explain in the April 28th Journal of the American Medical Association. But previous research has suggested either a neutral effect or even potential harm from B vitamins.

The multicenter, double-blinded DIVINe trial, conducted between 2001 and 2007, enrolled 238 patients with diabetic nephropathy. Senior author Dr. J. David Spence, from the University of Western Ontario, London, and colleagues randomly assigned patients to treatment with a single daily tablet containing 2.5 mg folic acid, 25 mg vitamin B6 and 1 mg vitamin B12, or to placebo.

A total of 118 subjects completed the 36-month follow-up, but 119 subjects in each group were included in the modified intention-to-treat analyses.

Subjects in the B-vitamin group had a