The job of the kidneys is to rid the body of protein waste products and maintain the right levels of fluid, sodium, potassium and phosphorus in your body. When the kidneys fail fluids and waste products collect in the blood to toxic levels. Although dialysis removes some of your body's excess waste products, it doesn't completely replace natural kidney function. For this reason, dialysis patients need to control the intake of certain foods and fluids. By following your diet, you can feel better and avoid complications.