Nephrology for the Family Physician - O.I. Bakaliuk 2003

Modern approaches to the treatment of specific pathological conditions associated with renal impairment
Dietary therapy in kidney diseases

When addressing this issue, the emphasis, in our view, should shift toward the dietary management of patients with chronic renal failure (CRF). This is justified by the fact that the onset of CRF in The final stage of various Kidney diseases shares similar clinical symptoms and requires unified approaches to medical Nutrition therapy, whereas the Treatment of acute Glomerulonephritis (GN), Nephrotic Syndrome (NS), and ACUTE RENAL FAILURE is invariably carried out in a hospital Setting. Nevertheless, we will also outline the fundamental principles of diet therapy for acute and chronic GN without Impairment of the nitrogen-excreting function of the Kidneys.

The basic principle of the diet in acute GN is the restriction of sodium chloride and fluids while maintaining adequate caloric intake and vitamin levels. In the presence of edema, particularly during its progression, dietary sodium chloride is restricted to 0.2-0.3 g/day. It is advisable to recommend any sodium-free diet, such as rice, fruit-rice, fruit-vegetable, or potato diets (where the potassium-to-sodium ratio is approximately 20:1). Subsequently, The amount of dietary salt and fluid intake is determined by urine output, Blood pressure levels, the presence of edema, and the degree of tissue hydrophilicity, although sodium chloride is generally restricted for 2 to 3 months or even longer. It should be borne in mind, however, that prolonged restriction of dietary sodium chloride can lead to severe adverse effects, such as hypochloremic azotemia. Therefore, such patients are advised to undergo so-called "zig-zags," meaning periods of periodically increasing the amount of salt in their diet for short intervals. During the diet expansion phase, a potato-apple-fat regimen is used: 1.5-2 kg of boiled, fried, or baked potatoes, 75 g of butter soaked in Water, and 500 g of well-sweetened apples (M.N. Tumanovsky et al., 1963). Diuretic effects are provided by zucchini, beets, lettuce leaves, watermelons, pumpkins, melons, grapes, and bananas. Vegetable oil, boiled and fried onions, pepper, mustard, parsley, dried dill, cranberries, and caraway seeds are also introduced into the diet (E.M. Neiko, 2000); protein restriction (to 0.4-0.5 g/kg of body weight/day) is applied only in cases of hyperazotemia, although nowadays recommendations regarding the advisability of restricting protein to 0.8 g/kg of body weight/day, even when the nitrogen-excreting renal function is preserved, are increasingly appearing (L. Pyryg, 2001).

The goal of diet therapy in chronic GN is to improve the overall course of the disease. The restriction or excess of certain food ingredients in the diet is limited by the functional state of the kidneys, although THE PRINCIPLE OF a nutritionally complete diet must remain paramount under any circumstances.

When renal function is preserved, the diet of patients with chronic GN includes, alongside porridges and juices, lean meats, fish, milk, eggs, rice, vegetable oil, honey, sour cream, and plant-based foods rich in Vitamins C and P (lemons, rose hips, black currants). Fasting or restriction days are considered appropriate: sugar days (150-200 g of sugar per 2 glasses of water, optionally with fruit/berry juice or lemon); vegetable days (1.5 kg of various vegetables in the form of unsalted salads dressed with a small amount of sour cream, vegetable oil, or preserves); watermelon days (1.5 kg of ripe watermelon divided into 5 portions); fruit or berry days (1.5 kg of identical fruits or berries divided into 5 portions, with 15 g of sugar added to each portion); and compote days (compote made from 1.5 kg of raw fruits/berries or 250 g of dried fruits, adding 100 g of sugar and 4 glasses of water, with the mixture divided into 6 portions).

Dietary management is of particularly crucial importance in CRF.

The main principle of the diet is the restriction of dietary protein. This approach was applied almost empirically for a long time. Researchers' interest increased significantly following the well-reasoned report by S. Giovanetti et al. (1964) on the high efficacy in CRF of a diet with severely restricted daily protein intake (24-25 g/day) and a caloric intake of around 2500 kcal/day, even in the presence of a marked decrease in the Glomerular Filtration rate (GFR down to 10 ml/min). Difficulties in organizing such a diet are primarily associated with the need to exclude foods containing plant Proteins, such as bread, potatoes, and porridges. In addition, to ensure adequate caloric intake, one must consume large amounts of sweets and fats (jam, honey, butter, vegetable oil). However, the Giovanetti diet gained widespread acceptance, and later publications appeared detailing its modifications tailored to the national dietary habits of patients.

Let us point out, for instance, the dietary variant developed at the clinic of A.Ya. Yaroshevsky (1971): patients daily receive 100 g of butter, 100 g of sugar and sour cream, 50 g of dry grape wine, 50-100 g of honey or preserves, a boiled egg, fresh vegetables and fruits, and 1 g of Methionine. The caloric content of such a ration is 2500-2700 kcal/day, containing 18-24 g of proteins, 110-115 g of fats, 350-400 g of CARBOHYDRATES, 0.6 g of sodium, 2.5 g of potassium, and Essential Amino Acids. Instead of bread, the menu includes "bread rolls" baked from starch and rice flour with The addition of sour cream. Meat and fish products are excluded from the diet; to limit phosphorus intake, legumes, nuts, and cocoa are forbidden. Spices (bay leaf, cinnamon) are added to improve palatability. It should be noted that advice on including easily digestible alcohol in the diet is also found in other recommendations (Ch. Waterhouse, 1992)—preserving endogenous protein at the expense of the caloric, diuretic, and antioxidant effects of alcohol.

Below are other Variants of the low-protein diet.

Variant 1. Breakfast: semolina porridge (200 g), milk (50 g), sugar (10 g), butter (10 g), preserves (honey, 50 g). Second breakfast: egg (1 pc.), sour cream (100 g). Lunch: vegetarian borscht (300 g), sugar (2 g), butter (10 g), sour cream (20 g), boiled potatoes (50 g), tomatoes (20 g), onions (20 g), carrots, beets, cabbage (50 g), vermicelli (50 g), fresh apple kissel (200 g). Dinner: fried potatoes (200 g).

Variant 2. Breakfast: boiled potatoes (200 g), tea with sugar (10 g). Second breakfast: egg (1 pc.), sour cream (100 g). Lunch: pearl barley soup (300 g), braised cabbage (300 g), apple kissel (300 g). Dinner: vinaigrette salad (300 g), tea with sugar, honey, or preserves (50 g).

Variant 3. Breakfast: mashed potatoes (300 g), tea with sugar. Second breakfast: egg (1 pc.), sour cream (100 g). Lunch: vegetarian borscht (300 g), boiled potatoes (200 g), apple kissel (200 g). Dinner: buckwheat porridge (70 g), tea with sugar, honey, or preserves (50 g).

Variant 4. Breakfast: buckwheat porridge (50 g), tea with lemon (sugar - 20 g). Second breakfast: carrot patties with sour cream (carrots - 300 g, butter - 20 g, vegetable oil - 20 g, starch - 20 g, sour cream - 20 g), egg (1 pc.), honey - 100 g. Lunch: rice soup (rice - 20 g, potatoes - 100 g, tomato paste - 10 g, butter - 10 g), vegetable stew (potatoes - 300 g, cabbage - 200 g, carrots - 20 g, onions - 10 g, butter - 20 g), egg (1 pc.), fruit compote (fruits - 100 g, sugar - 30 g). Dinner: semolina porridge (semolina - 30 g, sugar - 20 g, butter - 20 g), fruit juice - 200 g.

Variant 5. Breakfast: rice porridge with butter (rice - 40 g, butter - 20 g, sugar - 20 g), tea with preserves or honey (100 g). Second breakfast: fried potatoes (potatoes - 300 g, butter - 20 g, vegetable oil - 20 g), egg (1 pc.), tea (sugar - 30 g), fruits (200 g). Lunch: beet borscht (beets - 150 g, potatoes - 100 g, carrots - 20 g), cabbage patties (cabbage - 200 g, starch - 20 g, butter - 20 g, onions - 10 g, sour cream - 30 g), egg (1 pc.), fruit mors (fruits - 100 g). Dinner: buckwheat porridge (buckwheat groats - 50 g, butter - 20 g), tea (sugar - 30 g).

The Use of special protein-free bread, artificial sago, and protein-free vermicelli is recommended. Certain companies manufacture protein-free bread and semi-finished products for home preparation ("Aproten", Italy; nutritional formula "Survimed Renal", FRG). It is also beneficial to enrich the low-protein diet with fish oil (W.F. Clark et al., 1993).

At the clinic of the Ukrainian Institute of Urology and Nephrology (A.P. Peleshchuk, 1983; T.D. Nykula, 1983, 2001), two variants of a low-protein diet with a balanced Amino Acid Composition have been developed—Table No. 7A (21 g protein/day) and Table No. 7B (40 g protein/day), which utilize traditional Ukrainian dishes and specialized products. These diets incorporate plant fats and pectin-rich products (beets, carrots, apples, pears, marmalade), to which small amounts of seasonings and spices are added (weak vinegar solution, onions, caraway, nutmeg, anise, vanillin, pepper, mustard, horseradish, citric acid).

In these diets, the protein content is restricted to 20-40 g/day, respectively; fat intake ranges from 85-99 g/day, and carbohydrates from 326-346 g/day. The ENERGY VALUE OF such a daily ration is 2191-2337 kcal, ensuring an adequate supply of essential amino acids (valine, Histidine, isoleucine, leucine, Lysine, methionine, Threonine, Tryptophan, phenylalanine), minerals (sodium, potassium, calcium, magnesium, phosphorus, iron), and vitamins (beta-carotene, vitamins A, B₁, B₂, PP, C).

The Nutrition Institute of the Russian Federation has developed additional variants of such diets (7P and 7B), which are also generally characterized by high energy value, as well as an adequate content of polyunsaturated Fatty acids and pectin substances. A detailed description of these diets, as well as the diet for patients undergoing hemodialysis (7G), is provided in the monograph by T.D. Nykula (2001).

The so-called potato-egg diet, proposed by R. Kluthe et al. (1967), has become widespread. The rationale for its use stems from data obtained by the authors showing that a rational combination of animal and plant proteins in the diet promotes nitrogen conservation in body Tissues while minimizing the intake of exogenous nitrogenous products.

M.Ya. Ratner et al. (1987) proposed a variant of this diet: breakfast consists of rice porridge and apple compote; lunch features beet borscht, potato pancakes, and whey; second lunch includes starch muffins and tea; dinner consists of fried eggs with lard, and oranges.

Dietary treatment should be initiated as early as the preazotemic stage of CRF. When the GFR is around 40 ml/min, the protein content should be 40-60 g/day. Such a moderate reduction in daily dietary protein does not lead to patient exhaustion, yet it reduces the workload on the kidneys. When the GFR drops to 20-30 ml/min, the amount of protein in the daily ration is reduced to 30-40 g.

L.A. Pyryg et al. (2001) cite the following calculation: at GFR values within 50-70 ml/min, the patient receives 1 g of protein/kg of body weight/day; at 10-40 ml/min, 0.5-0.6 g of protein/kg of body weight/day; and at 5-10 ml/min, 0.3-0.4 g of protein/kg of body weight/day.

Diets with significantly restricted protein content (up to 25 g/day) are especially effective in early or moderately pronounced CRF (with blood creatinine levels in the range of 0.27-0.62 mmol/L). However, their prolonged use is accompanied by The Development of a negative nitrogen balance, acidosis, and hypernatremia; therefore, subsequent daily protein intake should be at least 0.6 g/kg of body weight/day, split roughly equally between animal and plant sources. A low-protein diet is not prescribed when the GFR is below 4-5 ml/min, creatininemia exceeds 0.7 mmol/L, or in the presence of severe dyspepsia, frequent vomiting, hemorrhagic diathesis, severe Heart Failure, drug-resistant arterial Hypertension, or Urinary Tract obstruction.

Finally, it should be noted that optimal Levels of Protein intake in CRF have not been definitively established, despite more than 50 years of study on this issue (A.G. Kucher, 1997; B. Cianciaruso et al., 1995).

To facilitate calculations when planning a low-protein menu, we provide the amounts of common animal food products (in grams) equivalent to 1 protein unit (7 g of biologically complete protein), as well as the protein content (in grams) in plant-based products (according to A.P. Peleshchuk, 1983).

1 protein unit is contained in 1 egg, 2 egg yolks, 50 g of fatty pork, 40 g of medium-fat pork, 55 g of fried pork sausage, 35 g of veal, 40 g of duck meat, 35 g of goose meat, 35 g of lean river fish, 230 g of milk, 55 g of cottage cheese, 35 g of ham, 30 g of smoked herring, 30 g of sardines in oil, and 50 g of processed cheese. 100 g of dark bread contains 3 g of protein; 150 g of vegetables, 1-2 g; 100 g of lettuce, 1 g; 150 g of potatoes, 3 g; 50 g of rice, 3.5 g; 50 g of dough, 6.5 g; 100 g of wheat flour, 12.1 g; 100 g of protein-free bread, 0.6-0.8 g; 100 g of protein-free flour, 3.8 g; and 100 g of protein-free semolina, 3.5 g. Foods such as butter (vegetable oil), margarine, lard, protein-free bread, protein-free semolina and flour, sugar, honey, and fruit caramel are prescribed without restriction. The effectiveness of such a diet is enhanced by supplementing it with 1-1.5 g of histidine and 0.3 g of iron per day.

Protein-restricted diet therapy is supplemented with parenteral administration of albumin. In this regard, It is worth noting the potential of using a novel plasma substitute—lactoprotein—developed at the Lviv Research Institute of Blood Pathology and Transfusion Medicine. Its composition is as follows: albumin – 50 g, 7% sodium lactate solution – 312 g, sodium chloride – 8 g, calcium chloride – 0.1 g, potassium chloride – 0.075 g, sodium bicarbonate – 0.1 g, glucose – 50 g, sodium caprylate – 3 g, water for injections – up to 1 liter. According to V.V. Orlyk (1999), the use of lactoprotein in the complex treatment of nephrological patients with advanced manifestations of chronic renal failure (CRF) contributed to the stabilization of hemodynamics, alleviation of uremic intoxication, lipoproteinemia, metabolic acidosis, and water-electrolyte imbalances.

A low-protein diet can be successfully supplemented with a dietary Supplement—wheat germ. The latter is prescribed at 1 tablespoon 2–3 times a day before meals, washed down with water or juice (T.D. Nykula, 2001).

One of the options for a protein-restricted diet is adding soy isolate (Supro-760) to the low-protein menu at a rate of 0.3 g of soy isolate/kg of body weight/day (S.I. Ryabov et al., 1998, 2000). This combination is rational from several Perspectives: as a complete protein (100 g of isolate contains 90 g of protein), soy isolate contains all essential Amino Acids and iron, while having a minimal content of undesirable ingredients such as potassium, sodium, and phosphorus. In addition, as a plant-based product, soy protein mitigates metabolic acidosis and stimulates hemopoiesis.

Hemodynamic and non-hemodynamic effects of a low-protein diet are distinguished. Hemodynamic effects include counteracting excessive dilation of the afferent arteriole and the dilation of the efferent arteriole; non-hemodynamic effects include reducing proteinuria and tubular hemosiderosis, inhibiting Lipid Peroxidation processes, decreasing parathyroid hormone production, alleviating the overload of renal tubules with Calcium and phosphorus, reducing ammonium production, and normalizing the balance between protein Synthesis and degradation (S.I. Ryabov et al., 1999).

Overall, it should be noted that a low-protein diet is part of a group of clinical and experimental approaches aimed at slowing down the progression rate of CRF, which are actively being developed today (Scheme 4, G.A. Muller, 1996).

Further interest in low-protein diets grew in connection with attempts to use dietary supplements in the form of essential amino acids (L-leucine, L-isoleucine, L-lysine, L-methionine, L-phenylalanine, L-threonine, L-tryptophan, L-valine, L-Tyrosine, histidine) per se or, even better, in the form of their keto analogues (M. Walser et al., 1973, 1987).

According to M. Walser et al. (1987), the use of amino acids in CRF helps restore a normal nitrogen balance alongside their simultaneous anabolic effect. Among the preparations of this type, we should mention Ketosteril (Germany), in which keto acids and methionine are present as calcium salts, serving as an additional source of calcium and providing a phosphate-binding effect. The use of diets incorporating amino acids is accompanied by another clinically significant effect—the reduction of hyperphosphatemia, a key factor in the progression of CRF. Thus, along with its nephroprotective effect, such a diet prevents the development of secondary hyperparathyroidism and its negative impact on calcium METABOLISM (Zh.D. Semydotska et al., 1999; G. Barsotti et al., 1996).

For adults, Ketosteril is prescribed at 12–20 tablets per day; for children, at 1 tablet/kg of body weight/day for 3–8 months.

The approach to improving the quality of life of patients with CRF by diversifying the diet while using amino acids and a minimal amount of nitrogen-containing substances has been termed the Swedish diet (J. Bergstrom, 1984; M. Walser et al., 1997).

After transferring patients to standard maintenance hemodialysis (12–15 hours/week), the protein content in the diet is increased to 1–1.2 g/kg of body weight/day, and the total caloric intake to 35 kcal/kg of body weight/day (N.L. Lifshits et al., 1999). At the same time, the intake of phosphates, potatoes (boiled twice, with the water after the first boiling discarded), and fruits is restricted.

Below are dietary options for dialysis patients.

Option 1. Breakfast: egg (1 pc.), rice porridge (60.0), honey, tea with sugar. Lunch: vegetarian borscht (300.0), fried fish with mashed potatoes (150.0), apples. Dinner: mashed potatoes (300.0), vegetable salad (200.0), milk (200.0).

Option 2. Breakfast: egg (1 pc.), buckwheat porridge (60.0), jam, tea. Lunch: noodle soup (300.0), stewed potatoes with meat (150.0), apples. Dinner: vegetable salad (200.0), plum juice (200.0).

Option 3. Breakfast: egg (1 pc.), semolina porridge (200.0), sour cream (100.0). Lunch: vegetarian borscht (300.0), pilaf (200.0), apple compote. Dinner: mashed potatoes (200.0), vegetable salad (200.0), milk (200.0).

Following kidney transplantation, the diet restricts only animal fats (the amount of such fats must not exceed 40–50 g/day) and easily digestible carbohydrates. At the same time, the content of lipotropic substances and Pectins is increased.

The administration of herbal remedies in the complex treatment of these conditions requires a strictly individual approach with a detailed Analysis of the clinical situation. The fundamentals of phytotherapy have been partially outlined by us in various sections when discussing the treatment of specific diseases. Nevertheless, we recommend enthusiasts of this method to consult sources where the issues of renal phytotherapy are thoroughly and thoroughly substantiated (D. Yordanov et al., 1972; Asp. Boychinov, 1972; M.O. Garbarets, V.G. Zapadnyuk, 1982; F.I. Mamchur, 1984; L.G. Dudchenko et al., 1986; A.A. Krylov et al., 1992; I.S. Chekman, V.S. Danylenko, 1992; Ye.S. Tovstukha, 1994; S.M. Drohovoz, 1995; Ye.M. Neyko, 2000; T.D. Nykula, 2001).