Vitamin B dangerous for diabetics with kidney disease

Vitamin B therapy should not be prescribed to diabetics with kidney disease; those who are using it should stop the regimen, a new study suggests. The study is published in the April 28 edition of the Journal of the American Medical Association

The study, led by Dr. David Spence and colleagues at The University of Western Ontario, showed that diabetics using vitamin B treatment consisting of folic acid, bitamin B6 and vitamin B12 had a more severe decline in kidney function, which is measured by glomerular filtration rate or GFR.

GFR is used to evaluate the level of kidney function.

Additionally, those who used the vitamin B therapy were twice as likely to have heart and stroke incidents, the researchers found.

Dr. Spence and colleagues performed the study in hopes that they might observe the high dose vitamin B therapy might actually improve kidney function and reduce the risk of heart attacks and stroke. The results are surprising.

Diabetic nephropathy is kidney disease, or damage resulting from diabetes.  According to a press release by University of Western Ontario, 21 million Americans and more three million Canadians have diabetes; more than 40 percent of diabetics will develop nephropathy.

Dr. Spence did find that high doses of vitamin B were associated with reduced levels of homocysteine in those who were treated.  Homocysteine is believed to increase clotting of the blood, but there is a debate over how much this amino acid could contribute to the risk of coronary heart disease, stroke, and peripheral vascular disease.

"Because B vitamins are water soluble, we suspect that while healthy people would excrete excess vitamins in urine, those with renal failure would not be able to do so, perhaps causing the adverse affects we have seen in this study," said Spence. 

"Vitamin B therapy may still be beneficial in people with normal kidney function, but this is clear evidence that high doses of vitamin B should not be given to those with kidney problems." 

David Liu and editing by Rachel Stockton