A protein-reduced diet can reduce the concentration of urinary-excreted substances (substances that need to be excreted through the urine) to keep the symptoms at bay and delay the onset of dialysis or kidney transplantation for as long as possible. Less protein means less stress. The normal average diet contains in the healthy 1.0 to 1.5 g of protein per body kilogram of body weight. That's too much for sick kidneys.
Protein: find the right dose
For the nutrition of a patient with chronic renal insufficiency limiting the protein intake is always a kind of "tightrope walk", because this quickly creates the risk of undersupply with the vital amino acids. Amino acids are building blocks of the proteins (protein) and have besides the structure of the body mass other functions in the body. They act as enzymes, hormones, antibodies in the immune system, the transmission of nerve impulses and much more.
In energy deficits, both the body protein and the few permitted dietary protein are used for energy supply. This in turn leads to an undesirable increase of urea (degradation product of protein) in the blood. However, the dietary requirements depend on the different stages of chronic renal insufficiency and are based on laboratory values. Through an adapted diet sufferers can actively influence the course of the disease.
Dietary protein should be limited according to the severity of chronic renal insufficiency. As a minimum of the protein, however, it must not be less than 0.5 g protein per body kilogram, so that it does not come to the degradation of the body substance. Patients with advanced renal insufficiency should generally have the daily protein intake stabilized at 40 to 60 g.
- It is recommended to use low-protein dietetic special products (low-protein starch, low-protein flours and products made from it, such as bread and pastries).
- Choose high quality protein to provide the essential amino acids in sufficient form. High-quality protein mixtures are ensured by a combination of potatoes and egg, beans and egg, milk and wheat, egg and wheat, legumes and wheat, as well as legumes and milk. The potato-egg mixture has the highest biological value (= number of grams of body protein, which can be built up from 100 g of dietary protein).
In addition to energy supply, fats are suppliers of essential fatty acids and carriers of fat-soluble vitamins.
- Make sure you have enough fat with plenty of monounsaturated fatty acids (eg olive oil or rapeseed oil) and polyunsaturated fatty acids (eg corn oil or thistle oil).
The different sugars are pure carbohydrates and can be used in common amounts. Carbohydrate fortification may be needed to provide adequate energy.
- Carbohydrate carriers such as bread, biscuits and pasta also contain protein and, in the case of advanced kidney disease, are to be exchanged in whole or in part by low-protein special products.
It is important to ensure adequate energy intake, as in insufficient energy intake of the body uses the already limited food protein for energy. The consequence is the unwanted increase of urinary substances in the blood.
- Take at least 35 to 40 calories per kilogram of body weight per day. For energy accumulation carbohydrates such as glucose, table sugar or prescription dietary foods (low protein and low in electrolyte and at the same time high energy) can be used. A fat enrichment of the food is also possible by adding dietary margarine.
- Check your weight daily and see your doctor and dietician if you have a lot of weight.
The ability of the kidney to excrete water does not subside until the end-stage of the disease. Until then, to relieve the kidney, a high fluid intake of 2 to 3 liters is required to flush out the urine-containing substances. In general, the following golden rule applies to avoid edema (storage of water):
- Drink as much as the amount of urine excreted the day before plus 500 ml.
Sodium affects blood pressure and is closely related to the patient's thirst.
- Moderately use saline and prefer fluoridated iodised salt. The daily diet should not contain more than 6 to 8 grams of saline. That's the case with the average diet. When cooking, if possible, do not fry or sizzle at table.
- Do not use diet salts. These are products that consist entirely or partially of potassium salts and can cause hyperkalemia.
- All prepared meals, sauces or broths have a high salt content.
The potassium excretion remains largely normal until an advanced stage of chronic renal insufficiency. A low-potassium diet is usually required only when the amount of urine has decreased significantly (less than 1000 ml per day). An elevated potassium level in the blood can be very dangerous and lead to muscle weakness, cardiac arrhythmias and even heart failure. Since potassium is a water-soluble mineral, the potassium content of potatoes, vegetables and fruits can be reduced by appropriate preparation and preparation.
- Avoid foods rich in potassium, such as spinach, legumes, tomato paste, dried fruit, apricots, bananas, chocolate, nuts, dried fruits, vegetable and fruit juices.
- A reduction in the potassium content (10 to 50 percent) of fruits, vegetables, salads and potatoes is achieved by mincing and rinsing several times.
- Do not continue to use cooking water from vegetables and potatoes.
- Remove the juice from canned fruits and prepare yourself a fresh lemon marinade.
Phosphorus / phosphate
A low-protein diet is usually low in phosphates at the same time. The daily intake of phosphate should not exceed 1000 mg per day, otherwise problems with the bone metabolism may occur.
- Phosphate-rich foods include hard and processed cheese, nuts, whole grains, dried boletus, smoked foods, chocolate and cola drinks.
- If the dietary phosphate reduction is not sufficient, medication (phosphate binders) must be added by the doctor to prevent phosphate uptake in the intestine.
Vitamins and other minerals
A low-protein and low-potassium diet can lead to long-term deficiencies in the supply of vitamins and minerals.
- Important is a targeted substitution of calcium, iron, zinc, vitamin D, vitamins of the B-complex and water-soluble vitamins by the doctor.
Constipation (constipation) in renal insufficiency
In the final stages of chronic renal insufficiency, there is often constipation due to low fluid intake. The consumption of fiber-containing foods such as whole grains, fruits, vegetables and salads usually ensures a healthy intestinal activity and a reduction in the occurrence and severity of diet-related hyperlipidemia (lipid metabolism disorder).
As increased potassium or phosphorus levels limit the consumption of these foods, the risk of constipation is higher. Due to delayed defecation, it can cause bloating, bloating and abdominal pain. The use of conventional laxatives can lead to dependency. For the treatment of constipation, a lactulose preparation is recommended for chronic renal insufficiency in the pre-dialysis stage and dialysis stage.
The knowledge of having to be affected by chronic kidney disease and having to adapt to it, for many affected and their relatives, means a profound change in their life story and life planning. In addition to all the medical needs that come to patients, nutritional therapy is part of the ways to delay the progression of chronic renal failure.