By Dr. Mara Cazzola
Epidemiology
Chronic renal failure is a public health problem. Today, in the world, it is possible to register an incidence of more than 2 million new patients, but the WHO declares that this trend is constantly growing. In fact, it is estimated that in 2020, in China alone, dialysis will be more than 1 million, while as many as 30 million will be affected by a kidney disease due to hypertension.
Metabolic alterations
A patient suffering from stage V renal insufficiency is called "uremic". Uremia is a term composed etymologically of two words: "ouron", from the Greek, which means urine and "haima", blood. The term refers to the metabolic and hydroelectrolyte alterations associated with the severity of this clinical condition. A uremic patient has to face: alterations of the water balance, lack of sodium excretion, a possible appearance of hyperkalaemia, metabolic acidosis, hypertension, insulin resistance, changes in calcium / phosphorus metabolism, reduced chemotactic and phagocytic capacity of immune cells, progressive anemia and cognitive disorders (such as memory loss, poor concentration and inattention) that involve both the CNS and the SNP, alterations of the lipidemic picture concerning the concentrations of cholesterol, HDL, LDL, triglycerides and homocysteine often aggravated by micro and macro albuminuria and by a negative nitrogen balance which frequently leads to a reduction in muscle mass.
Diet in the Uremic Patient
A uremic patient is assigned to replacement therapy. To follow the medical treatment suggested by your nephrologist, highly personalized and ad hoc, for these patients is essential in order to preserve a state of health as excellent as possible and optimize their quality of life. As soon as you enter substitution therapy (the timing of entry into dialysis is decided by the doctor and the staff) the conservative one ceases, therefore the diet and the eating habits of these patients undergo important and considerable modifications.
The calorie-protein recommendations suggested by nutrition books and European guidelines are different based on the dialysis method adopted (hemodialysis or peritoneal dialysis).
- They suggest for hemodialysis:
- 30-40kcal / pro kg of ideal weight / day
- Proteins 1.2g / pro kg of ideal weight / day
- Phosphorus <15mg / g of protein
- Potassium <2-3g / day
- Sodium <2g / day
- Calcium: maximum level of 2 g / day
- Quantity of liquids: residual diuresis + 500ml / day
- For peritoneal dialysis, instead:
- 30-35 kcal / pro kg of ideal weight / day
- Protein 1.2-1.5 / pro kg of ideal weight / day
- Phosphorus <15mg / g of protein
- Potassium <3 g / day
- Sodium according to tolerance
- Quantity of liquids: residual diuresis + 500ml / day + ultrafiltrate
The protein intake is higher compared to a patient on hemodialysis because, during peritoneal dialysis, the losses of this nutrient are more conspicuous: in case of peritonitis, there may also be a loss of 20g. Peritoneal dialysis exploits the osmolarity of glucose for the purification of blood and, in this way, a surplus of sugar absorption occurs. This extra calorie must be considered in the preparation of the diet plan.
The EBPG Nutrition Guidelines recommend the following vitamin intake for patients on replacement therapy:
- Thiamine: 0.6-1.2mg / day
- Riboflavin: 1, 1-1, 3mg / day
- Pyridoxine: 10mg / day
- Ascorbic acid: 75-90mg / day. Vitamin C deficiency is common especially in hemodialysis patients
- Folic acid: 1mg / day
- Vitamin B12: 2.4µg / day
- Niacin: 14-16mg / day
- Biotin: 30µg / day
- Pantothenic: 5mg / day
- Vitamin A: 700-900 µg / day (supplements are not recommended)
- Vitamin E: 400-800IU (useful contribution to prevent cardiovascular events and muscle cramps)
- Vitamin K: 90-120 µg / day (supplementation is not necessary except in patients who receive antibiotics for a long period of treatment and who have blood clotting problems)
For minerals, the Guidelines report:
- Iron: 8mg / day for men, 15mg / day for women. Additional intakes should be recommended to patients who are treated with ESA (erythropoiesis stimulator) to maintain adequate serum levels of transferrin, ferritin and hemoglobin. Oral iron supplements should be taken between meals (or at least 2 hours before or 1 hour later) to maximize mineral absorption and not simultaneously with phosphorus chelators
- Zinc: 10-15mg / day for men, 8-12mg / day for women. A supplementation of 50mg / day is recommended for 3-6 months only for those patients who have overt symptoms of zinc deficiency (dermal fragility, impotence, peripheral neuropathy, alteration of taste perception and food odors)
- Selenium: 55μg / day. Selenium supplementation is recommended in patients with symptoms of deficiency: heart disease, myopathies, thyroid dysfunction, hemolysis, dermatitis.
For those suffering from chronic kidney failure there is not enough evidence to prohibit the intake of 3-4 cups of coffee a day. Further studies are needed to investigate the benefits of this substance, especially in the elderly, children and those with a positive family history of calcium lithiasis.
Studies on the relationship between the consumption of red wine and kidney disease are very limited: in patients with diabetic nephropathy in substitution treatment, the moderate consumption of red wine and a diet rich in both polyphenols and antioxidants slow the progression of renal damage. Patients with kidney disease have a high cardiovascular risk and wine, if moderate and controlled consumption is present, is a valid food-accessory to be included in a meal.
For patients on dialysis therapy, who must therefore keep the supply of potassium under control, the following are to be avoided : dry and oily fruits, biscuits or other types of sweets containing chocolate, some types of fish, spices and ready-made sauces on the market.
Another trick is to carry out physical activity : it does not mean following grueling training programs, but it is sufficient to ride a bike, walk or, if the physical conditions allow it, attend swimming lessons. Athletes take potassium supplements to make up for sweating losses: following an active lifestyle is a great help in eliminating potassium. In boiled zucchini, boiled turnips, boiled carrots, chard, chicory, aubergines, cucumbers and onions there is a low potassium content. As far as fruit is concerned, you can safely consume: strawberries, apples, pears, tangerines and syrup. Oranges, cherries, mandarins and grapes are medium in potassium.
A diet rich in proteins, such as that indicated in replacement therapy, is therefore rich in phosphorus. This mineral, contained mainly in milk and derivatives, egg yolk, meat and fish has a recommended intake of less than 15 mg / pro g of protein, and a diet with a low intake of these foods can lead to the risk of developing a protein-calorie malnutrition. Foods such as fish, meat, milk and derivatives cannot and must not be completely removed from the diet: the dietitian's ability lies in planning a diet with a sufficient supply of protein but without excess of phosphorus .
The energy distribution of meals must be departed in five daily events: a breakfast, two snacks, one in mid-morning and one in mid-afternoon, a lunch and a dinner. At breakfast there is a solid and a liquid food; in mid-morning or mid-afternoon it is essential to eat something to avoid reaching the next main meal too hungry. You can propose yogurt with some cereals, or an infusion and a solid food (rusks or dry biscuits), but you can also orient yourself towards a small sandwich with a slice of cheese or sliced (the quantities must be proportionate to the daily energy). It is usual for lunch to consist of a dry first course, accompanied by a dish, a side dish and a portion of bread, all followed by fresh seasonal fruit. The first course can be seasoned with vegetable sauce and, once a week, these can be replaced by meat or fish. If you like it, you can add some grits in small quantities (generally to taste). Same composition for dinner (first course, dish, side dish, bread and fruit): the first course is in vegetable broth (on average, the portion in broth is halved compared to the dry one) and the only seasoning allowed is the extra oil virgin olive oil, due to its important nutritional properties (avoid margarine and butter). It is advisable to eat at least twice a week, at lunch, a first course in which the seasoning is represented by legumes or a vegetable-based minestrone. The portions of the food must be proportionate to the patient's daily energy needs, in order to guarantee the adequate contribution of both macro and micronutrients. For the preparation of a suitable and acceptable dietary plan, the dietitian must take into account the preferences of the foods of chronic uremics: red meat, fish and poultry, eggs, in hemodialysis, are less welcome than peritoneal. In this way, pleasure and pleasure are combined with the duty and respect for dietary norms in order to preserve the most optimal state of health.
Following the diet is important
Following the diet is essential for patients, regardless of the method adopted: the dietary plan makes dialysis treatment more effective and improves the subject's nutritional status.
Since the uremic condition is not perfectly corrected by dialysis methods, depending on the method used to assess the state of nutrition, malnutrition in dialysis is present from 18% to 75% and is one of the factors responsible for high mortality . It can be of two types:
- Caloric-protein malnutrition (Protein Energy Wasting, PEW) present from 10% to 70% with an average of 40% in chronic dialysis patients
- Excess malnutrition present in 50% of sick subjects
The major causes of malnutrition are related to the patient's severe uremic condition, to the dialysis method adopted (there may be intradialytic amino acid losses; infectious complications, such as peritonitis; blood loss, such as filter rupture or prolonged access bleeding in hemodialysis), to medical therapy (intake of drugs causing nausea, vomiting or altering the perception of taste and taste of food) and to the psychological-economic sphere (uremic patients, especially if on hemodialysis, are mostly elderly and they can face depression, mourning, loneliness, lack of self-sufficiency and autonomy in preparing and procuring a meal). These high percentages of malnutrition show that the underestimation of nutrition in dialysis is widespread: the production of a dietary and nutrition education program is hampered by a lack of interest in nutrition, economic limits and the high mortality rate of uremic patients. In fact, these patients have serious clinical problems to which the experts in the field give the precedence, allowing to transgress broadly in the feeding in order to obtain from it a moment of gratification.
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