Diet in chronic kidney disease. What to eat and what to avoid?

Kidney disease often forces you to change your eating habits. Some food products aggravate the symptoms associated with a given disease, and some nutrients accelerate the development of the disease. That is why it is so important that the diet in chronic kidney disease is carried out by a dietitian and that the patient strictly adheres to the recommendations of a specialist.

Calorific value and glycemic index of the diet in chronic kidney disease

A properly balanced diet in terms of calories is of great importance in the case of kidney disease, because the excess caloric content and obesity related to it may contribute to the progression of the disease, as well as lead to the development of comorbidities such as: hypertension , atherosclerosis .

Unfortunately, in patients with chronic kidney disease, there is a tendency to the advantage of adipose tissue over muscle, so from the very beginning they are more predisposed to metabolic disorders and gaining excess body weight.

For this reason, the amount of energy a patient should consume is 30-35 kcal / kg, with 65% of energy coming from carbohydrates, fat should be 30%, and protein the remaining 5%.

A dietitian planning a diet for a person with kidney disease should not forget to include regular physical activity in it (although it is sometimes difficult to implement, as patients usually show greater fatigue and weakness). This allows the patient to obtain more muscle tissue, and thus improve insulin management.

In turn, the diet, in addition to balancing the correct calorific value and appropriate composition of the proportion of macronutrients, should be based on products with a low glycemic index. Such a diet reduces the risk of insulin resistance (it is very common in patients with kidney diseases) and accelerates the reduction of body fat.

Protein and the kidneys

In kidney diseases, it is recommended to introduce a low-protein diet because it allows you to lower the concentration of urea in the blood. Urea is the end product of protein metabolism that is formed during a process known as the urea cycle.

First, when the proteins are converted, ammonia is created that is toxic to the body, and then it is neutralized into less harmful urea. And although it is not poisonous like ammonia, its accumulation is not beneficial for the body.

Elevated urea levels lead to either oliguria or anuria . In the final stage of chronic kidney disease, with too much accumulated urea , uremia may even develop , which can be diagnosed by:

• significant weakening,
• loss of appetite,
• reduced resistance to infections,
• or greater fatigue.

In kidney disease, the supply of protein is significantly reduced, reducing its amount from, for example, 0.8 g per kg of body weight to 0.6 g or less. In patients with chronic kidney disease, whose condition is balanced and they do not have comorbid diseases such as diabetes, it is recommended to consume 0.6 g of protein per each kilogram of body weight per day.

On the other hand, in advanced stages of chronic kidney disease, the protein is administered in an amount below 0.4 g per kg / d with the simultaneous inclusion of ketoanalogues (these are compounds that resemble amino acids in structure, but are devoid of nitrogen, which is conducive to increasing the concentration of urea in the blood).

The significant benefits of a low-protein diet include not only lowering the serum urea concentration, but also:

• decrease in phosphate levels,
• improving the lipid profile,
• reduction of metabolic acidosis (disturbances between acids and bases),
• reduction of hyperkalemia (excess potassium),
• improvement of insulin sensitivity,
• delay in the development of the disease.

The role of fats in chronic kidney disease

Due to the limited supply of protein, fats should not be reduced in the diet. However, as a minimum, saturated fatty acids should be used, which may constitute at most 7% of the allowable 30% of lipid energy.

This is mainly due to the fact that people with chronic kidney disease very often also have concomitant metabolic diseases, e.g. diabetes, which disturb the lipid metabolism. The saturated fats that should be used to a small extent include, among others butter , cream , cheese or fatty meat.

In turn, the remaining 23% of energy derived from fats should be allocated to monounsaturated and polyunsaturated fats. The advantage here should be fats rich in anti-inflammatory omega-3 acids found in fatty fish such as salmon , mackerel , herring , or oils such as linseed or rapeseed.

In addition, omega-6 fatty acids, which can be found in evening primrose oil , borage oil or sunflower oil , will be beneficial (but not in excess) . They have a positive effect on the body, but because they compete with omega-3 acids in the body and may limit their availability, it is worth consuming them in moderation.

In addition, the diet of people with kidney disease should include monounsaturated fatty acids such as: olive oil or sesame oil .

How Much Carbohydrate Do I Eat?

Due to the fact that the amount of protein in the diet is significantly reduced and the amount of fat cannot be consumed as much again, it is necessary to take into account the amount of carbohydrates in the diet in the amount of 65% of the daily energy.

However, these should be valuable carbohydrates such as: groats , wholemeal bread, wholemeal pasta or brown rice.

Minerals - phosphorus and calcium

The kidneys are an organ that regulates the levels of calcium and phosphorus . When its functioning is deteriorated, the economy of these elements is disturbed. Therefore, in chronic kidney disease, it is recommended to limit phosphorus intake to 800-1000 mg / day.

Products rich in phosphorus include: milk , cheese, eggs, buckwheat, sunflower seeds.

Consuming them in large amounts should be avoided (although they are limited in a low-protein diet for people with kidney problems), which at the same time, unfortunately, can lead to calcium deficiency (often the same products that contain phosphorus also contain calcium).

In order to prevent calcium deficiencies, it is sometimes necessary to supplement it, but this is decided by the doctor.

Minerals - potassium

The initial stages of renal failure may lead to increased potassium loss . In such a case, care should be taken to supply such products that contain a large amount of it, e.g. tomatoes , bananas, sweet potatoes.

As kidney disease develops and its functions weaken, excessive accumulation of potassium in the body and an increase in its concentration in the blood occurs. hyperkalemia. You should then limit the level of potassium consumed to 2000-2500 mg / day.

In order to reduce its amount, the diet should, for example, soak vegetables and cook dishes longer. In addition, you should reduce the consumption of: sweet potatoes, tomatoes, avocados, potatoes, apricots , soybeans, etc.

It is best to do it under the supervision of a dietitian and a doctor to avoid a significant depletion of this element in the daily menu.

Should sodium intake be restricted in kidney disease?

Chronic kidney disease leads to a reduced ability to excrete sodium. So when it comes to a situation that the patient develops swelling, increased thirst or arterial hypertension, then its consumption should be limited to 5 mg a day.

Sodium is found not only in the salt we use to salt our food. It is hidden in various food products that we would not suspect, e.g. corn flakes, rolls, meats.

In addition, we can find it in large amounts in: canned food, smoked meats, silage, crisps , yellow cheese or stock cubes.