The renal diet restricts the consumption of foods and beverages that make the kidneys work harder. When the kidneys function normally, they work with other organs to remove waste from the blood and maintain a proper balance of fluid in the circulatory system. When kidney disease damages the kidneys, the organs do not maintain these normal functions. The renal diet aims to reduce the complications associated with kidney disease.
Significance
Normal kidneys maintain normal levels of phosphorus, sodium and potassium in the blood. When the kidneys function properly, they also remove the byproducts of protein metabolism from the blood. Damaged kidneys do not carry out these functions, so the renal diet limits daily intake of protein, sodium, potassium and phosphorus. The National Kidney and Urologic Diseases Information Clearinghouse explains that reducing the intake of these substances prevents them from building up in the blood and improves the health of people who have kidney disease.
Function
Patients with kidney disease follow a renal diet to slow down the progression of kidney disease. Kidney disease has five stages that correspond to the severity of the condition. Stage one represents the mildest form of kidney disease, while stage five represents the most severe form, according to the National Kidney Foundation. Physicians also refer to stage five kidney disease as end-stage renal disease. Following a renal diet does not completely reverse kidney disease, but it can prevent the disease from advancing into the most severe stages.
Effects
Following a renal diet reduces some of the effects of kidney disease on the body. MayoClinic.com explains that too much sodium increases blood pressure and causes swelling in people with impaired kidney function. Reducing sodium intake reduces blood pressure levels and relieves water retention. Eating foods that contain low levels of phosphorus and potassium prevents these minerals from building up in the blood. Because protein breakdown creates waste products, eating less protein reduces the amount of waste produced by the body. This means the kidneys do not have to work as hard to filter waste from the blood.
Meal Planning
Careful meal planning helps patients with kidney disease follow the renal diets prescribed by their physicians. VCU Medical Center recommends 1/2-cup servings of fruits and vegetables, with no added sugar or salt. Patients with kidney disease can reduce their phosphorus consumption by avoiding or limiting the intake of cola drinks, cheese, milk, potatoes and corn. Avoiding salted nuts, potato chips, fast food, frozen meals, canned vegetables and canned soups reduces the amount of sodium consumed at each meal. Eating small portions of red meat and poultry reduces the amount of protein consumed each day.
Considerations
Some people with kidney disease have other serious medical conditions. This makes careful diet planning even more important. People with kidney disease and diabetes need to follow a diabetic renal diet, which has the same restrictions as the renal diet and also controls the amount of carbohydrates consumed each day, as explained by the American Association of Kidney Patients. Those with kidney disease and heart disease also need to control the amount of cholesterol and fat consumed each day. Anyone who has kidney disease along with another medical condition should seek the advice of a physician or registered dietitian to determine the best way to plan meals and snacks.
References
- National Kidney and Urologic Diseases Information Clearinghouse: Eat Right to Feel Right on Hemodialysis
- National Kidney Foundation: Glomerular Filtration Rate (GFR)
- MayoClinic.com: Sodium: How to Tame Your Salt Habit Now
- VCU Medical Center: The Renal Diet (PDF)
- American Association of Kidney Patients: How Can I Follow My Diabetic and Renal Diet Restrictions?
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