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High-dose B-vitamins harmful to patients with diabetic nephropathy

Clinical Question:
Are high-dose B-vitamins beneficial for adults with diabetic nephropathy?

Bottom Line:
High-dose B-vitamins may actually increase the risk of adverse outcomes -- including myocardial infarction, stroke, and mortality -- in adults with both type 1 and type 2 diabetic nephropathy. High-dose B-vitamins are also either harmful or of no benefit to patients at high risk of cardiovascular disease, chronic renal failure, and cognitive impairment. The B-vitamins belong on the same "Do Not Use" shelf alongside the vitamin E. (LOE = 1b)

House AA, Eliasziw M, Cattran DC, et al. Effect of B-vitamin therapy on progression of diabetic nephropathy. A randomized controlled trial. JAMA 2010;303(16):1603-1609.  [PMID:20424250]

Study Design:
Randomized controlled trial (double-blinded)



Outpatient (specialty)

Supplemental folic acid and B vitamins are not beneficial in adults at high risk of cardiovascular disease or in those with chronic renal failure. Whether this is also true for patients with diabetic nephropathy is unknown. These investigators identified 238 adults, 18 years or older, with type 1 or type 2 diabetes and nephropathy defined as at least 300 mg per day of urinary albumin excretion. Patients randomly received, in double-blind fashion (concealed allocation assignment), a once-daily capsule containing folic acid (2.5 mg), pyridoxine (25 mg), and cyanocobalamin (1 mg), or an identical placebo. Individuals assessing outcomes remained masked to treatment group assignment. Complete follow-up occurred for more than 96% of patients for a median length of 32 months. Analyses were by intention to treat. Although plasma homocysteine levels were significantly lower in the intervention group, the patients assigned to the B-vitamin group had a significantly greater reduction in renal glomerular filtration rate compared with patients in the control group. There was no difference in the need for dialysis between the 2 treatment groups. Most important, patients in the B-vitamin supplementation group also experienced an increased risk of the composite outcome of myocardial infarction, stroke, and all-cause mortality (number needed to treat to harm = 11).


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