Patients with chronic kidney disease are often encouraged to modify their diet to prevent complications and slow further deterioration of kidney function. Diet modification becomes especially important as chronic kidney disease progresses. Patients may benefit from the services of a dietician for their special dietary needs associated with kidney disease.
Chronic Kidney Disease
Although many factors can contribute to kidney failure, diabetes remains the leading risk factor in the development of renal disease. Chronic kidney disease (CKD) is characterized as a slow deterioration of kidney function. As the kidney deteriorates, it becomes less effective in the removal of fluid, wastes, toxins and other metabolites. In addition, the kidney may lose the ability to produce important biomolecules and regulate electrolytes. Many patients require hemodialysis and a kidney transplant once kidney function completely declines.
Electrolytes and Minerals
The kidneys are primarily responsible for regulating the amount of electrolytes such as sodium and potassium in our body. They also regulate the amounts of certain minerals within our body including calcium and magnesium. As kidney function declines, these minerals may accumulate and cause adverse effects. Unfortunately, in the case of calcium, the kidney synthesizes the active form of vitamin D that is required for dietary calcium absorption. As vitamin D synthesis is impaired in CKD, patients may have calcium levels that are too low. Routine blood work is often required to determine how much minerals and electrolytes should be contained in the diet.
Low-Protein Diet
CKD patients face a unique problem when it comes to protein intake. On the one hand, kidney disease may result in protein loss from the body. In addition, hemodialysis patients may have increased protein needs due to their catabolic state. On the other hand, protein breakdown produces metabolites that place heavy burden on the kidney and in some cases are toxic to kidney cells. In general, a restriction in dietary protein intake may help to slow the progression of kidney disease.
MDRD Study
According to the University of Pittsburgh in a document prepared for the American Dietetics Association, the Modification of Diet in Renal Disease Trial (MDRD) found that patients with moderate renal failure, defined as a glomerular filtration rate between 25 to 55 ml/min, had a slower decline in renal function when placed on a low-protein diet of 0.58 g/kg/day versus a standard protein diet of 1.3 g/kg/day. Unfortunately, the report states that lower protein intake did not have a significant impact on renal function in patients with severe kidney disease.
Phosphorus
Hemodialysis and CKD patients are frequently told to limit their intake of dietary phosphorus. Unfortunately, phosphorus is commonly found in many foods including dairy, meat, fish and beans. In addition, popular beverages such as soda contain high amounts of phosphorus. When the kidney cannot efficiently remove phosphorus, it can accumulate and complex with calcium to form crystals that may lodge and cause injury inside of tissues and organs. Patients with concerns regarding chronic kidney disease should contact their physician. In many cases, a certified dietician can help to formulate an appropriate diet plan.
References
- National Kidney Foundation: Nutrition and Chronic Kidney Disease
- National Kidney and Urologic Diseases Information Clearinghouse: Nutrition for Later Chronic Kidney Disease in Adults
- University of Pittsburgh: Cost-Effectiveness of Nutrition Therapy in the MDRD Study
- MayoClinic.com: Chronic kidney failure
