Dietary supplements can be downright dangerous for kidney patients. Even a simple multivitamin with potassium and phosphorus can cause serious problems--and even death--especially in patients approaching end stage renal disease. If you have kidney disease, always consult your nephrologist before you take any dietary supplement or over-the-counter drug. Taking dietary supplements is more likely to cause serious health problems than it is to improve kidney function.
Vitamin Risks
As renal function declines, the kidneys are less able to clear substances from the blood. This is particularly true for oil soluble vitamins. Levels of vitamins A, E, and K can become unnaturally high in patients with chronic kidney disease. Consequently, doctors do not recommend supplementation with these vitamins.
Mineral Risks--Potassium
The difference in potassium concentrations on either side of the nerve membrane makes it possible for the nerve to fire. Since nervous function is critical to life, healthy kidneys filter out excess potassium and keep potassium levels within a healthy range. As renal failure approaches, kidneys are less able to perform this critical function, so potassium levels can become elevated. Nerves begin to misfire, possibly causing irregular heartbeats. Dietary supplements that contain potassium aggravate this problem.
Mineral Risks - Phosphorus
Healthy kidneys also filter phosphorus from the blood. By keeping a healthy balance between phosphorus and calcium, the kidneys insure that calcium stays in the bones. If phosphorus levels get too high--as they often do in kidney patients--the phosphorus starts to pull calcium from the bones. This reduces bone density and weakens bones. Dietary supplements that contain phosphorus can aggravate this problem
Safe Supplementation
As patients approach renal failure, they are often malnourished because the number of foods that they can safely eat becomes rather small. If this occurs, nephrologists might prescribe special vitamins that don't include potassium, phosphorus and other dangerous nutrients. While these vitamins will not improve renal function, they will make you healthier so that the transition to dialysis or transplantation is easier.
Fish Oil
Many nephrologists allow their patients to take high doses of fish oil. While this supplement does not improve kidney function, Dr. James Donadio published a very influential paper in the August 1999 issue of the "Journal of the American Society of Nephrology" that shows that supplementation with fish oil may slow the rate of renal decline. While the jury is still out on this finding, this supplement is generally permitted because it appears to be relatively harmless.
References
- National Institute of Diabetes and Digestive and Kidney Diseases: Chronic Kidney Disease (CKD) and D Assessment, Management, and Diet: Treating CKD Patients Who Are Not on Dialysis - An Overview Guide
- National Institute of Diabetes and Digestive and Kidney Diseases: Treatment Methods for Kidney Failure: Hemodialysis
- National Institute of Diabetes and Digestive and Kidney Diseases: Chronic Kidney Disease-Mineral and Bone Disorder
- National Kidney Foundation: Potassium and Your CKD Diet
- National Kidney Foundation: Phosphorus and Your CKD Diet
- "Journal of the American Society of Nephrology;" The Long-Term Outcome of Patients with IgA Nephropathy Treated with Fish Oil in a Controlled Trial; Dr. J.V. Donadio, et al; August 1999
