I. The importance of dietary treatment
Normal kidney has the functions of forming urine, excreting metabolic waste, regulating water, electrolytes, acid-base balance, secreting erythropoietin and synthesizing active vitamin D. When kidney function is impaired, a series of symptoms and signs such as proteinuria, edema, hypertension, anemia, metabolic acidosis, azotemia and uremia can appear. Diet therapy can reduce the formation of metabolic waste, reduce the intake of harmful substances, maintain water, electrolytes, acid-base balance, maintain good nutrition, reduce the burden of renal excretion, reduce further damage to the surviving kidney units, and delay the development of the disease, which is an essential measure for the treatment of chronic renal insufficiency.
Second, the principles and methods of dietary therapy
1.Protein.
(1) The final metabolites of protein are urea, uric acid, creatinine and other nitrogenous substances, which are mainly excreted by the kidneys. When the amount of protein in the diet exceeds the body’s needs, the excess will be decomposed. Therefore, the amount of protein should be limited in the first place.
(2) The extent to which various proteins are utilized in the body (biomass value) varies. Eggs, milk, meat, fish, poultry and other animal proteins have a high biomass value and are high-quality proteins, which produce less metabolic waste. Rice, noodles, grains, beans and soy products and other plant-based proteins have lower raw material prices and produce more metabolic waste. Therefore, the intake of plant-based protein should be reduced as much as possible, and the proportion of high-quality protein should be increased accordingly under the premise that the total amount of protein remains unchanged, both to limit the quantity of protein and to improve the quality of protein.
(3) Low-protein diet is not the lower the better, but should be arranged according to the actual situation and according to the kidney function. The supply of calories must be ensured in the case of ensuring a low protein diet, and only when adequate supply of calories is given can protein be fully utilized.
(4) Normal protein diet is about 1g per kg body weight per day, and low protein diet is 0.6g per kg body weight per day. low protein diet must be supplemented with essential amino acids to adequately maintain nutrition and ensure protein metabolism. 3 times a week for hemodialysis patients is 1.0-1.2g/kg per day, of which 75% should be high quality protein.
2. Calories.
Sufficient calorie intake is required to ensure that the daily protein intake is fully utilized and to reduce the breakdown of protein to provide heat. The general requirement is 30-35 kcal per kg of body weight, at least to keep the weight from decreasing. The source of calories is provided by sugar, vegetable fats and oils, and low protein starch.
3. Sodium.
The amount of sodium in the diet should depend on the function of the kidneys and the presence or absence of swelling and hypertension. Patients with renal insufficiency should not exceed 3g per day, generally 2-3g is appropriate. Sodium is not only found in salt, but also in soy sauce, monosodium glutamate, and ketchup, so you should eat less processed and pickled foods and choose more natural and unprocessed foods. Food with limited sodium is light and tasteless, so it is recommended to use sugar and vinegar method and add onion, ginger, garlic, cinnamon and other seasonings to increase the patient’s appetite.
4.Potassium
The amount of potassium in the diet mainly depends on the blood potassium. When urine is low and blood potassium is high, high potassium foods such as fresh fruits, vegetables, melons, various vegetable soups and meat soups should be restricted; when blood potassium is low or there is polyuria, vomiting, diarrhea, and when eating too little, potassium intake, especially fruits, should be increased.
5.Calcium
Patients mostly have hypocalcemia, and dietary supplementation is difficult to meet the needs, must be supplemented with calcium, that is, calcium, but also can reduce the absorption of phosphorus in the diet.
6.Phosphorus and purine
Patients mostly have hyperphosphatemia and hyperuricemia (uric acid is the final metabolite of purine), so in limiting phosphorus and purine intake, eat less animal offal, broth, necessary to make with the taking of phosphorus binding agent.
7.Vitamins
Additional water-soluble vitamins, especially vitamin B6, C, folic acid, etc., should be added.
8.Water
For those who are not on dialysis, the water intake is the previous day’s urine volume plus 500-800ml, check the weight and keep the weight stable; for those on hemodialysis, the daily weight change should not exceed 0.5kg as a principle.
In short, dietary treatment should follow the following principles: high quality low protein, low phosphorus, low purine; adequate calories, rich vitamins and minerals such as calcium and iron; moderate amounts of sodium, potassium and easily digestible food.