Nutritional Tips for Kidney Cancer Patients

The kidneys are the main organs of regulation and excretion of the human body. The main function of the kidneys is filtering blood and expelling waste products and excess water.

Single-kidney patients (who had a kidney removed because of cancer) may suffer from impaired kidney functionality. As a result, the contralateral kidney has to work twice as hard. In these patients it is recommended to follow an appropriate diet even during the administration of specific cancer medical treatment. Nutritional directions should be customized and tailored for each patient, based on their kidney functionality (assessed through specific examinations evaluated by your doctor). Generally speaking, we can provide some advice on the type of diet to follow, and on which macronutrients (carbohydrates, lipids and proteins) and micronutrients (vitamins and minerals) you should pay attention to to avoid further impairing in the kidney’s functionality.

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The protein content
should be carefully evaluated according to the level of kidney failure of the patient. The doctor will indicate how many grams of protein the patient will have to eat daily. Proteins are mainly found in meat, fish, dairy products, eggs, legumes, tofu, but also in nuts, cereals, seeds and vegetables. Since proteins are often present in food, it is necessary to calculate their intake correctly—to avoid the risk of taking an excess of them.

If the kidney function is impaired, it is recommended to keep also the sodium intake under control. It is therefore necessary to accurately establish the amount of sodium that does not cause in the patient overload, nor insufficient intake. Sodium (called non-discretionary sodium) is present in all foods, so we have to reduce the so-called discretionary sodium, that is, the one added in cooking and/or at the table. A low sodium diet therefore excludes canned food or salt-preserved food and promotes the choice of foods with a low content of sodium.

In the presence of kidney failure, the potassium content must also be controlled, to avoid an excess increase of the levels of this microelement in the blood. According to the LARN (Nutrient Reference Assumption Levels), the recommended potassium intake level for healthy adults is 3.9 g/die. Based on the degree of kidney failure and potassium levels in the blood, the doctor will suggest the correct amount of potassium to take in. Potassium is found in a great many foods, but for sure vegetables and fruits are its main sources. The potassium content in food is significantly reduced when foods are cut into small pieces and cooked in abundant liquid (the latter instead will become rich in potassium). Steaming, microwave and pressure cooking unlike boiling keep the potassium content quite unchanged.

As for the amount of phosphorus to take in, LARN recommend a consumption of 700 mg/die from the healthy adult population. As with potassium, in patients with kidney cancer it is necessary to evaluate every single situation in order to determine the correct daily dose. The highest concentrations of phosphorus are found in cereal seeds (11 mg/g in wheat germ) and legumes (3 to 6 mg/g). Other sources of phosphorus are eggs, white meat, fish, cereals (about 1-2 mg/g), milk (about 0.9 mg/g) and vegetables (0.4 – 0.7 mg/g).