potassium, a nutrient important for muscle functioning
phosphorous, a mineral
How does the nutrient affect the body? Normally, kidneys filter many substances from the blood. Eventually these substances are passed through the body in the urine. When the kidneys are damaged, they cannot filter the blood. Substances can build-up to harmful levels. This build-up can damage other organs of the body and cause numerous problems. A diet for kidney disease limits certain nutrients to prevent this toxic build-up.
Information The kidneys also make hormones needed by the body, such as hormones used in making bones and blood. The kidneys have other roles such as a major control for blood pressure.
People with kidney disease are at risk for vitamin deficiencies and anaemia. Their bodies may not be able to make muscle tissue and bones as usual. The extra fluid and sodium in the blood stream can cause high blood pressure. Hormonal changes can cause cholesterol and other fats in the blood to be high. The build-up of toxic substances can make a person with kidney disease feel ill. In children, all these conditions may prevent normal growth and development.
Many people with kidney disease must undergo kidney dialysis, a process that filters the blood through a machine or bags to remove the toxic substances.
A diet for kidney disease takes much planning. It is a very personalised diet. The degree to which each nutrient needs to be restricted varies from individual to individual. Kidney disease usually requires frequent visits to a doctor who specialises in kidney disorders. A dietician is needed to help make meal plans that include the right amounts of each nutrient and to instruct the patient on their special diet. Frequent blood tests show which nutrients need to be limited.
The diet must include just enough protein to provide the essential amino acids needed by the body. The amount needed depends on a person's weight and whether they are on dialysis or not. Meats, eggs, dairy products, nuts and legumes are the main sources of protein. People with kidney disease need to be very careful about the amount of protein they eat. Protein by-products are one of the substances that the kidneys filter for toxic substances. Often, people with kidney disease are advised to get their protein from animal sources. This is because animal protein contains all the essential amino acids. This way they can eat a small amount of protein but still get all of their essential amino acids. Nuts and legumes do not contain all of the essential amino acids. Dialysis removes extra protein from the blood. The diet may include more protein for people on dialysis.
The amount of sodium allowed depends on the kidney condition. Often it is restricted and usually means limiting table salt. Many processed, canned and convenience foods cannot be eaten.
Fruits, vegetables and dairy products may be limited because they are high in potassium.
Restricting the amount of meat and milk eaten helps to control the amount of phosphorous, saturated fat and cholesterol in the diet.
Diets for kidney disease must include a lot of carbohydrate and unsaturated fat to provide enough kilojoules to prevent weight loss. The amount of fluids a person is allowed to drink depends on how much fluid is taken in and urine output.
Due to the many food restrictions, people with kidney disease usually need supplements of vitamins, iron and other minerals. It is important to talk with a doctor and dietician before taking extra supplements when kidney disease exists.
Author: Lanette Meyer, CD Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 19/10/2004 Contributors Potential conflict of interest information for reviewers available on request
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