People with kidney (or renal) disease must follow an extremely strict diet. Simply eating "healthy" is not even an option. The kidneys' job is to filter. When the kidneys fail, there are certain minerals and products that are no longer filtered. These products build up in the blood stream and the person eventually has to have dialysis to pull those products out and "clean the bloodstream." Restricting foods that are harmful helps renal patients avoid complications.
Excessive salt intake makes a person retain water. Retaining water can be very dangerous for people with kidney failure, as they cannot get rid of extra fluid through urinating. Excessive salt can also lead to high blood pressure, a problem often associated with kidney failure. Chronic high blood pressure can lead to worsening of kidney failure.
One of the most dangerous foods for kidney failure patients is foods high in potassium. Potassium is filtered through the kidneys. High potassium levels can cause heart failure, dangerous heart rhythms and even sudden cardiac death. Foods high in potassium are bananas, oranges, tomatoes, dried fruits and vegetables, milk, chocolate, nuts and seeds and dairy products. Low potassium foods include apples, berries, watermelon, fresh beans, lettuce, cucumbers, onions and vanilla-flavored desserts. A renal diet should contain less than 2000 mg of potassium a day. Many salt substitutes contain potassium, so it is imperative to read labels. Chewing tobacco and snuff also contain a lot of potassium, so these products should be avoided as well.
Foods high in phosphorus must also be avoided. Cola, peanut butter and nuts, liver, and dairy are all high in phosphorus. Broccoli, non-dairy creamers, sherbet, winter squashes and hard candy contain a low phosphorus content. Phosphorus not only builds up in the bloodstream, but it also draws calcium out of the bones, creating complications associated with low calcium levels. If patients cannot maintain their calcium levels by diet alone, their physician may prescribe calcium supplements for them.
Protein particles are some of the hardest for the kidneys to filter. The unfiltered proteins become urea, a waste product in the blood that makes renal patients very sick and must be dialyzed out to remove it. While protein is necessary for building and maintaining healthy muscle and fighting infection, it must be strictly limited. Foods high in protein include meat, poultry, eggs and milk. Fresh beans and vegetables are sources of low protein foods.
One of the most important dietary restrictions for kidney patients is to monitor their fluid intake. Persons in the latter stages of kidney failure become oliguric (produce very little urine) or even aliguric (produce absolutely no urine). The fluid builds up in their body between dialysis treatments. Too much fluid can cause fluid to build up in the lungs and even death. Fluids must be strictly limited, including foods that have a high water content.
It is extremely important, especially for renal patients, to read labels. Processed foods, such as frozen dinners and soups, are often very high in sodium. Many sauces, such as steak or barbecue sauce and spices such as rubs are high not only in sodium, but can be very high in potassium as well. Reading labels will help to avoid these foods.