Many CKD patients and their families have questions about vitamins – should they take vitamins, which ones and how much? Often they receive different advice from different people. Over-the-counter vitamins seem like a safe “back-up” to a healthy diet and the benefits, while often vague, are touted by the media, alternative healthcare practitioners, and numerous books.
This past week a study was published in the Journal of American Medical Association that all CKD patients with diabetes should be aware of. Researchers were trying to determine if vitamin therapy could slow down the progression of kidney disease and prevent heart attacks and stroke. In this study, patients with diabetes and diabetic kidney disease who took high dose B-vitamin therapy had a greater decrease in kidney function and much higher rates of heart attacks and strokes compared with those who took a placebo!
The doses of folic acid, vitamin B12, and, vitamin B6 used in the study are considered “pharmacological” which means to have a “drug-like” effect and significantly higher than the daily recommended intake. What is concerning however is that some over-the-counter vitamin preparations contain high amounts of some of these same vitamins. B complex vitamins may provide as much as four times the Vitamin B6 used in this study and a single nutrient supplement like vitamin B12 can be commonly found at the dose used. These vitamins are all “water soluble” and are filtered by your kidneys.
What does this mean for someone with chronic kidney disease and diabetes? Well I would strongly recommend talking to your kidney care team and reviewing all of your vitamins. If you’re taking any large doses of B-vitamins that weren’t prescribed by your physician, stop them. Talk to your renal team before starting any new products.
This study leaves us with many questions but it serves as an important warning that you can have too much of a good thing.
Reference: Effect of B-Vitamin Therapy on Progression of Diabetic Nephropathy. JAMA. 2010;303(16):1603-1609