Curated by Dr. Mara Cazzola
Epidemiology
Chronic kidney 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, there will be more than 1 million dialysis patients, while as many as 30 million will be suffering from kidney disease due to hypertension. Diabetes is also one of the main causes of kidney disease: it is estimated that in 2030 there will be 366 million diabetic patients, therefore, diabetic glomerulopathy is constantly increasing. In Europe, the costs of dialysis absorb up to 1,7% of national health expenditure. The main objective of Western countries, therefore, is cost containment. The problem for emerging countries is more critical, because it is not possible to access dialysis and transplantation, due to the prohibitive costs; the prevention of kidney damage is therefore the only possible way to offer hope for the future to the inhabitants of these countries.
Metabolic alterations
A patient with stage V renal insufficiency is referred to as "uremic". Uremia is a term etymologically composed of two words: "ouron", from the Greek, which means urine and "haima", blood. The term refers to the metabolic and hydroelectrolytic alterations associated with the severity of this clinical condition. An uremic patient undergoes: alterations in 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 the immune cells, progressive anemia and cognitive disorders (such as memory loss, poor concentration and inattention) involving both the CNS and the PNS, 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 destined for replacement therapy. Following the medical treatment suggested by your nephrologist, highly personalized and ad hoc, is essential for these patients in order to preserve the most excellent state of health possible and optimize their quality of life. The moment in which replacement therapy is entered (the timing of entry into dialysis is decided by the doctor and the staff) the conservative one ceases, therefore the diet and eating habits of these patients undergo important and considerable changes.
The calorie-protein recommendations suggested by the nutrition books and the European guidelines are different according to the dialysis method adopted (hemodialysis or peritoneal dialysis).
- For hemodialysis they suggest:
- 30-40kcal / per kg of ideal weight / day
- Protein 1,2g / per kg of ideal weight / day
- Phosphorus <15mg / g of protein
- Potassium <2-3g / day
- Sodium <2g / die
- Calcium: maximum level of 2 g / day
- Amount of liquids: residual diuresis + 500ml / day
- For peritoneal dialysis, on the other hand:
- 30-35 kcal / pro kg of ideal weight / day
- Proteins 1,2-1,5 / per kg of ideal weight / day
- Phosphorus <15mg / g of protein
- Potassium <3 g / day
- Sodium according to tolerance
- Amount of liquids: residual diuresis + 500ml / day + ultrafiltered
The protein intake is higher than in a patient on hemodialysis because, in the course of peritoneal dialysis, the losses of this nutrient are more conspicuous: in the case of peritonitis, there may also be a loss of 20g. Peritoneal dialysis exploits the osmolarity of glucose for blood purification and, in this way, a surplus of sugar absorption occurs. This extra calorie needs to be considered when writing your diet plan.
The EBPG Nutrition Guidelines recommend the following vitamin intakes for patients on replacement therapy:
- Tiamina: 0,6-1,2mg / the
- Riboflavina: 1,1-1,3mg / the
- Piridossina: 10mg / die
- Ascorbic Acid: 75-90mg / day. Vitamin C deficiency is common especially in hemodialysis patients
- Folic Acid: 1mg / day
- Vitamin B12: 2,4µg / day
- Niacina: 14-16mg / the
- Biotina: 30µg / die
- Pantothenic: 5mg / day
- Vitamin A: 700-900 µg / day (supplements are not recommended)
- Vitamin E: 400-800UI (useful contribution in order 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 state:
- Iron: 8mg / day for men, 15mg / day for women. Additional intakes should be advised in patients who are treated with ESA (Erythropoiesis Stimulating Agent) to maintain an adequate serum level of transferrin, ferritin and hemoglobin. Oral iron supplements should be taken between meals (or at least 2 hours before or 1 hour after) to maximize mineral absorption and not simultaneously with phosphorus binders
- 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, altered perception of the taste and odors of food)
- Selenium: 55μg / day. Selenium supplementation is recommended in patients with deficiency symptoms: heart disease, myopathy, thyroid dysfunction, hemolysis, dermatitis.
For those suffering from chronic renal insufficiency there is insufficient evidence to prohibit the intake of 3-4 cups of coffee per day. Further studies are needed to investigate the benefits of this substance, especially in the elderly, in children and in those with a positive family history for calcium lithiasis.
Studies on the relationship between the consumption of Red wine and kidney disease are very limited: in patients with diabetic nephropathy on replacement therapy, moderate consumption of red wine and a diet rich in both polyphenols and antioxidants slow the progression of kidney damage. Patients with kidney disease have a high cardiovascular risk and wine, if the habit of moderate and controlled consumption is present, is a valid accessory food to be included in a meal.
For patients on dialysis therapy, who therefore have to keep their potassium intake under control, they are to be avoided above all: dried and oily fruit, biscuits or other types of sweets that contain chocolate, some types of fish, spices and ready-made sauces on the market. Some dietary salts, recommended for those suffering from hypertension, tend to replace normal sodium chloride with potassium: those suffering from chronic renal failure must therefore carefully read the nutritional label and the list of ingredients. Certain types of tropical and summer fruit should be avoided: bananas, kiwi, avocado, peaches, apricots. Among the vegetables, the consumption of spinach, artichokes, potatoes, rocket and aromatic herbs should be controlled. Some precautions help to control the final potassium intake: it is advisable to cut the vegetables into small pieces and boil them in plenty of water, to allow the mineral to dissolve. We suggest not to use the cooking liquid, as well as not to steam, microwave or pressure cooker.
Another trick consists in the engage in physical activity: it does not mean following exhausting training programs, but it is sufficient to ride a bicycle, walk or, if the physical conditions allow it, to attend swimming lessons. Athletes take potassium supplements to make up for losses due to sweating: following an active lifestyle is in fact an excellent aid in the elimination of potassium. In boiled courgettes, boiled turnips, boiled carrots, chard, chicory, aubergines, cucumbers and onions there is a low potassium content. As for fruit, they can be safely consumed: strawberries, apples, pears, tangerines and the syrup. Oranges, cherries, mandarins and grapes have a medium potassium content.
A diet rich in protein, such as that indicated in replacement therapy, is consequently 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 proteins, and a diet with a low intake of these foods can involve the risk of developing a calorie-protein malnutrition. Foods such as fish, meat, milk and derivatives cannot and must not be completely removed from the diet: the dietician's skill lies in the plan a diet with a sufficient supply of protein but without excess phosphorus.
The energy distribution of meals must be divided into five daily events: a breakfast, two snacks, one of which is mid-morning and one mid-afternoon, a lunch and a dinner. At breakfast there is a solid and a liquid food; In the mid-morning or mid-afternoon it is essential to eat something to avoid getting too hungry for the next main meal. You can offer yogurt with cereals, or an infusion and a solid food (rusks or dry biscuits), but you can also choose a small sandwich with a slice of cheese or cold cuts (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, you can add some parmesan in small quantities (usually 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 condiment allowed is extra- virgin olive oil, due to its important nutritional properties (avoid margarine and butter). It is advisable to consume at least twice a week, for lunch, a first course in which the sauce is represented by legumes or a vegetable-based soup. The portions of food must be proportionate to the patient's daily energy needs, in order to ensure adequate intake of both macro and micronutrients. To draw up an adequate and acceptable diet plan, the dietician must take into account the food preferences of chronic uremics: red meat, fish and poultry, eggs, on hemodialysis, are less welcome than peritoneal. In this way, pleasure and delight are combined with duty and compliance with dietary rules in order to preserve the best possible state of health.
Following the diet is important
Following the diet is essential for patients, regardless of the method adopted: the food plan makes dialysis treatment more effective and improves the subject's state of nutrition.
Since the uremic condition is not perfectly corrected by dialysis methods, depending on the method used for assessing the state of nutrition, malnutrition in dialysis is present from 18% to 75% and is one of the factors responsible for the high mortality . It can be of two types:
- 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 losses, such as rupture of the filter or prolonged bleeding of the access in hemodialysis), medical therapy (taking drugs that cause nausea, vomiting or that alter the perception of taste and taste of food) and the psychological-economic sphere (uremic patients, especially if on hemodialysis, are for the most part elderly and they can face depression, grief, loneliness, lack of self-sufficiency and autonomy in the preparation and procurement of the meal). These high rates of malnutrition demonstrate how widespread the underestimation of nutrition in dialysis: Production of a dietary and nutrition education program is hampered by low interest in nutrition, economic constraints and the high mortality rate of uremic patients. In fact, these patients have serious clinical problems that experts in the field give priority to, allowing them to transgress widely in nutrition in order to obtain a moment of gratification from it.
References
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- Binetti P, Marcelli M, Baisi R. Handbook of Clinical Nutrition and Applied Dietetic Sciences, Universo Publishing Company, reprint 2010
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- DavideBolignano, Giuseppe Coppolino, Antonio Barilà et al., Caffeine and kidney: what evidence right now? J RenNutr 2007; 17, ( 4), 225-234.
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