Diet For Kidney Disease
There are two types of diets for kidney disease.
How does the nutrient affect the body?
Normally, kidneys filter many substances from the blood. These substances include:
Eventually these substances are passed out of the body in the urine. When the kidneys are damaged, they cannot filter the blood as efficiently. Substances can build up to harmful levels, leading to damage to other organs and systems of the body. Certain substances can be restricted in the diet, in order to slow down this toxic buildup.
The kidneys also make hormones needed by the body. These include hormones that help make bones and blood cells. The kidneys also help control blood pressure by limiting the amount of fluid and salt in the bloodstream.
People with kidney disease are at risk for vitamin deficiencies. Their bodies may not be able to make certain blood cells, which can lead to anemia. Their kidneys also prevent the body from maintaining bones as usual. The extra fluid and sodium in the bloodstream that can accumulate as a result of kidney failure can lead to high blood pressure.
Hormonal changes can cause cholesterol and other fats in the blood to be high. The buildup of toxic substances can make a person with kidney disease feel ill. In children, all of these conditions may prevent normal growth and development.
PRE-DIALYSIS DIET Eating a low-protein diet before starting dialysis may help preserve kidney function. Protein restriction can delay the start of dialysis. The healthcare professional can determine whether a low-protein diet would be useful.
A registered dietitian should be consulted to help plan the diet. This diet limits the amount of protein in the diet to about 40g to 50g per day. The protein eaten should be of high quality. Lean meat, fish, poultry, and eggs are good sources of high quality protein. Other nutrients many be low in this type of diet, so a multiple vitamin including folic acid is usually recommended.
It is important that people following this type of diet get adequate calories from carbohydrates and fats. This keeps the body from using protein calories for energy. Sodium, including table salt, may also be restricted. It is also important to consult the healthcare professional about the advisability of salt substitutes. Individuals should consult with a registered dietitian to ensure that this diet is adequate in all nutrients.
DIET FOR PEOPLE ON DIALYSIS People who have ESRD must undergo dialysis or receive a kidney transplant. Dialysis is a process that filters the blood to remove toxic substances. There are two types of dialysis - hemodialysis and peritoneal dialysis. In hemodialysis, the person's blood is filtered through an artificial kidney machine. This machine removes waste products, as well as extra fluid and salt, from the blood just as the person's kidneys would if they were still working.
In peritoneal dialysis, the blood is cleaned inside the body using the abdominal cavity. Fluid is placed into the patient's abdominal cavity. The waste products from the blood pass into the fluid. The fluid and waste products are then drained from the abdominal cavity through a tube.
The diet for people on dialysis may limit the following nutrients:
Protein may or may not be restricted for people with ESRD. The decision depends on remaining kidney function and other factors. A nephrologist, a physician who specializes in kidney diseases, and a registered dietitian can provide guidance on optimal protein intake.
The amount of sodium is restricted in this diet. The following foods are usually limited:
- table salt
Salt substitutes should not be used because they contain potassium. Acceptable alternatives to salt include the following:
Fluid restrictions vary, depending on how much liquid the person's kidneys are able to remove. Any food that is liquid at room temperature contains water. Foods that have a high fluid content are as follows:
ice cream and sherbet
lettuce and celery
All of these foods add to a person's fluid intake. Fluid can build up between dialysis sessions, causing swelling and weight gain. The extra fluid affects the blood pressure and can put an extra strain on the heart.
Potassium Potassium is a mineral that affects how steadily the heart beats. Healthy kidneys keep the right amount of potassium in the blood to keep the heart beating at a steady pace. Potassium levels can rise between dialysis sessions and affect the heartbeat. Eating too much potassium can be very dangerous to the heart and may even cause death for a person on dialysis.
Potassium is found in many foods, including dairy products, meats, and dried beans. There are certain fruits that are especially high in potassium, such as:
cantaloupes, honeydew, and other melons
dates and other dried fruits
grapefruit and grapefruit juice
mangoes and papayas
nectarines and peaches
oranges and orange juice
prunes and prune juice
Vegetables that are high in potassium include the following:
- brussels sprouts
- dried beans and lentils
- fresh tomatoes, tomato paste and puree, and tomato juice
- lima beans and succotash
- pumpkins and squash
- spinach and Swiss chard
- vegetable juice
The kidneys play an important role in balancing the phosphorus and calcium in the body. When a person has kidney disease, the phosphorus from food may build up in the blood. Too much phosphorus in the blood pulls calcium from the bones, making them weaker and more likely to break. Also, too much phosphorus may make the skin itch.
The following foods are high in phosphorus and need to be restricted:
- cola drinks
- milk and cheese
- nuts and peanut butter
Most people on dialysis also need to take a phosphate binder to control the phosphorus in their blood between dialysis sessions. These medications act like sponges to soak up, or bind, phosphorus while it is in the stomach. Once it is bound, the phosphorus does not get into the blood but is instead passed out of the body in the stool.
Diets for kidney disease must include sufficient calories to prevent weight loss and the use of protein for energy. Due to the many food restrictions, people who have kidney disease usually need supplements of vitamins, iron, and calcium. A diet for kidney disease is very individualized and takes quite a bit of planning. How much each nutrient needs to be restricted varies from individual to individual.
Kidney disease usually requires frequent visits to the healthcare professional. A registered dietitian can help plan individualized meals. The dietitian can also instruct the patient on his or her special diet. Frequent blood tests show which nutrients need to be limited. Any new or worsening symptoms should be reported to the healthcare professional.
Mahan, K, MS, RD, CDE&Escott-Stump, S., MA, RD, LDN. (2000). Krause's Food, Nutrition,&Diet Therapy (10th ed.). Pennsylvania: W.B. Saunders Company.
The American Dietetic Association. (1996). Manual of Clinical Dietetics (5th ed.). Library of Congress Cataloging -in-Publication data.