Vitamins are an important part of a healthy diet, but research is needed to help further understand the benefits of each vitamin in maintaining health or preventing disease. B vitamins (eg, folic acid, B6, and B12) are one type of vitamin that is regularly studied to see if they prevent disease. Some research has indicated that B vitamins can help decrease blood levels of homocysteine (an amino acid in the blood associated with increased risk of heart disease, stroke, and kidney disease). The hope is that as a result of these benefits, B vitamins may decrease the risk of heart disease or stroke.
People with diabetes are at a higher risk for developing diseases such as stroke, heart disease, or nephropathy (kidney disease). Researchers from Canada wanted to determine what, if any, protective benefits vitamin B may have for people with diabetes. The study, published in the Journal of the American Medical Association, found that B-vitamin therapy may cause more harm than good.
The randomized trial included 252 patients with type 1 or type 2 diabetes and diabetic nephropathy. They were given high dose B-vitamin therapy that included daily supplements of folic acid, B6, and B12, or a placebo pill. Researchers followed the progress of patients and recorded relevant changes, such as decreases in kidney function (glomerular filtration rate), stroke, heart attack, and homocysteine levels. After 36 months, patients on vitamin therapy had:
There was no significant difference in the need for dialysis, long-term blood glucose levels, or blood pressure. There was also no significant difference in the individual rates of heart attack, stroke, need for opening heart arteries, or death.
A randomized trial is a reliable form of research, but it takes more than one study to confirm results. For patients with diabetic nephropathy, the vitamin B therapy appeared to have few benefits and some increased risks. The main benefit, decrease in homocysteine levels, did not appear to be protective against other serious illnesses. In fact, the vitamin therapy appeared to decrease kidney health and increase the risk of stroke.
This study is a good example of why people should be cautious when taking high doses of supplements. Some efforts at being healthier may actually increase risks. This study worked with high doses of vitamin B supplements. Most diets and typical multi-vitamins will not result in doses at these levels. It is important to talk to your doctor if you plan to take vitamins or supplements. This is even more important if you are managing a condition such as diabetes or kidney disease. Work with your doctor or a dietitian to plan how to get the most from your diet for your best health.
American Diabetes Association
National Diabetes Information Clearinghouse
House AA, Eliasziw M, Cattran DC, et al. Effect of B-vitamin therapy on progression of diabetic nephropathy: a randomized controlled trial.JAMA. 2010 Apr 28;303(16):1603-9.
Last reviewed 5/17/2010 by Brian P. Randall, MD