There are two types of diets for kidney disease. One type of diet is specifically for people who have progressive chronic renal failure, or kidney failure, but are not on dialysis yet. Along with medicine, a low-protein diet may slow the worsening of kidney failure. The other more restrictive type of diet is for people on dialysis whose kidneys have totally failed and are no longer working at all. This is called end stage renal disease, or ESRD.
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.
Eating a low-protein diet before starting dialysis may help preserve kidney function. Protein restriction can delay the start of dialysis. The healthcare provider will 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 speak to the healthcare provider before using any 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. They are 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 specialized 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:
Salt substitutes should not be used because they contain potassium. Acceptable alternatives to salt include the following:
spices that don’t contain salt
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 make the heart work harder. This can cause serious heart trouble.
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. It may even cause death. 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:
dried beans and lentils
fresh tomatoes, tomato paste and puree, and tomato juice
lima beans and succotash
pumpkins and squash
spinach and Swiss chard
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. Losing calcium makes the bones weak 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:
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. Instead, it is 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 takes a lot of planning. It is a very personalized diet. How much each nutrient needs to be restricted varies from individual to individual. Kidney disease usually requires frequent visits to the healthcare provider. 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 provider.
Functions and Sources
How does the nutrient affect the body?
Normally, kidneys filter many substances from the blood. These substances include the following:
by-products of chemical reactions in the body
waste products from the foods we eat
Eventually these substances are passed out of the body in the urine. When the kidneys are damaged, they cannot filter the blood. Substances can build up to harmful levels. This buildup can damage other organs of the body and cause numerous problems. Certain substances are restricted in the diet to prevent this toxic buildup.