●    Prevent malnutrition and secondary diseases.     

●    Avoid elevated potassium and phosphate levels.         

●    Improve the tolerance to the dialysis treatment .         

●    Regain the joy of eating and living.        

IMPORTANT: Diet must be adjusted for every patient on a case by case basis taking into consideration each individual situation and ongoing treatments.  The composition and characteristics of the diet should be ALWAYS discussed with a professional nutritionist and your doctor and needs to be adapted for every person.

In the case of advanced or terminal chronic kidney disease (renal failure), the kidneys can no longer fulfill their function as a filtering and excretory organ, which can lead to urine poisoning (uremia). Dialysis (also known as renal replacement therapy) now takes on this task. However, since dialysis does not detoxify the blood over 24 hours a day like a healthy kidney, it’s very difficult if not impossible for dialysis to remove all critical substances. For these reasons, patients undergoing dialysis treatment must be especially careful with their diets. They must take into consideration the intake of fluids, protein, vitamins (like vitamine B) and minerals such as potassium, sodium and phosphate.

There are general guidelines for the diet of dialysis patients but it is essential to always adapt them individually to the respective needs of every patient.

It’s very important that you discuss all medical questions with your doctor and coordinate your individual diet with a professional nutritionist.

Protein intake is very important in patients undergoing dialysis treatment. The protein building blocks (amino acids) that are transported in the blood are so small that they can be eliminated from the blood during dialysis and this can lead to a protein deficiency.

The intake of fluids is also of great importance in patients with renal problems and especially in dialysis patients. The kidneys are not capable of handling the same amount of liquid that healthy kidneys can so we need to help them by limiting the liquid volume intake during the day to avoid edema. Also, in dialysis patients, the less fluid you bring into dialysis, the less water has to be withdrawn from the body which helps patients better tolerate the dialysis.

Other elements to be considered when planning the diet of patients with kidney disease are Potassium and Phosphate balance/intake.

However harsh these dietary restrictions might seem, the principle “everything in moderation” is a good guiding principle for most patients and it is very much possible to have an appropriately restrictive diet while keeping the joy of eating alive!

Some important rules to keep your kidneys healthy are:

●   Eat fresh, healthy, mixed and if possible Mediterranean type of diet.      

●    Minimise processed foods and takeaway foods   

●    Keep a good control of your blood pressure.    

●   Control your blood sugar levels.    

●    Avoid smoking or drinking alcohol.      

●    Do aerobic exercise at least 5 times a week and during 30mins every time. The amount and intensity of exercise has to be discussed with your doctor and might be different in every patient’s case.

Some additional nutritional advice:

●    The amount of water consumed has adapted to the urine output. This is something that your doctor has to discuss with you in order to establish the correct amount of water you should be able to drink on a daily basis.

●    A diet low in salt helps keep the blood pressure under control.        

●    Do not eat too much or too little (animal) protein. Discuss with your doctor the correct amount of protein you can eat. This can vary from patient to patient.            

●    Avoid artificial phosphate additives which can increase the level of phosphate in your body.       

●    Consume enough energy. Discuss with your doctor so you can determine which daily calorie intake is adequate for you.

●    Prefer vegetable fats to animal fats. Fats of vegetable origin have a higher proportion of monounsaturated fatty acids which can help keep the heart healthy.

Let’s get into the details of every relevant dietary component:

An adequate energy supply is particularly important in all stages of kidney disease.

As for people with healthy kidneys, the daily energy required by the body is based on height, weight, age, gender and individual daily performance, that is, the amount of energy each individual uses on a day to day basis. Energy intake is measured in calories (cal) or kilocalories (kcal). People with kidney disease who are undergoing dialysis treatment must take into consideration that the disease itself and the dialysis treatment require a lot of energy and demand a big effort. This is why patients with kidney disease have a slightly higher energy requirement than healthy people. If too little calories are consumed, patients can quickly present with weakness, lack of energy, lack of strength and other signs of malnutrition or energy deficit. In patients with negative energy balance -that is, they burn more energy than they consume- both the body protein and the little permitted food protein are used for energy supply. This can lead to an undesirable increase of urea in the blood, byproduct of the use of protein as an energy source. This poses an additional burden on the kidneys.

The recommendations for energy intake for kidney disease and dialysis patients with light physical activity are:

At least 30 - 35 kcal / kg body weight / day*

Example: a person weighing 65 kg who does light physical activity daily needs at least 2275 kcal per day of energy.

*The optimal energy intake for CKD patients, as suggested by the Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, is 35 kcal/kg/d for individuals under the age of 60 and 30-35 kcal/kg/d for those aged 60 years or older.

For all patients with kidney disease and also for dialysis patients, the daily diet must be individually composed of the main nutrients protein, carbohydrates and fat, taking into account blood values ​​and residual kidney function.

Proteins are considered the basic building blocks of life.They are essential for building and maintaining muscles, they transport molecules such as oxygen, they keep us healthy as part of the immune system, and they fulfill important tasks of various kinds in all areas of the body.

Proteins play an important role in patients with kidney disease. Most of the waste products from protein metabolism, such as urea, uric acid and creatinine, are excreted in the urine.

Protein is broken down into urea in the liver and excreted via the kidneys in healthy people and by dialysis in dialysis patients.

A reduction in protein intake can sometimes delay the progression of some kidney diseases and thus the start of dialysis therapy. 

For patients diagnosed with kidney disease, it is especially advisable to limit the protein consumption from foods of animal origin. Animal foods are rich in purine and phosphates. Purines and phosphates have an impact on the kidneys and make them work harder to eliminate them and keep their presence balanced in the blood so limiting their intake can alleviate the burden on the kidneys.

The recommended protein intake for patients with kidney disease that are not on dialysis treatment is 0.8 - 1.0 g/kg of body weight. Ideally not more than half of it should come from animal foods. For patients with advanced kidney disease (GFR < 25mL/min/1.73m) the recommended amount of daily protein intake is 0,6-0,75g/kg.

Some patients might need a more strict protein intake restriction. Consultation with the treating physician and a specialist in nutrition should always guide these decisions on a case by case basis.

Protein restriction is usually necessary to alleviate the burden on the kidneys in patients with kidney failure but there needs to be an equilibrium between the intake of protein needed to maintain a lot of basic functions.

If you do not consume enough protein and calories you run the risk of using the body's own protein, This should be avoided as it can lead to the breakdown of your own muscles and, among other things, weakening of the immune system, formation of edemas, poor wound healing and overall weakness and reduced daily performance due to muscle breakdown.

Calculation of the protein requirement (example)*:

70 kg x 0.8 g / kg = 56 g total protein.

50 % of which as animal protein = 25–30 g from animal foods 

A simple rule of thumb for choosing animal foods:

●    Either per day: ¼ l milk product or soy milk product, 1–2 slices of cheese (60 g), 1 egg

●    Or: 1 portion of meat or fish and no other sources of animal protein 

Try to choose fresh foods without additives such as phosphate.

The "5 g protein" exchange table will help you assess the protein content of animal foods .

Phosphate is a mineral that plays an essential role in human bone metabolism. Normally, phosphate is taken up from food in the intestine and the excess is excreted through the kidneys. High phosphate levels are a sign of declining kidney function. A dysfunctional kidney is no longer able to ensure adequate removal of the phosphate. Excessive phosphate concentrations can lead to vascular calcification and this can lead to an increased risk of having a heart attack or stroke or of having circulatory disorders in the extremities. In addition, high phosphate levels can contribute to bone softening allowing fractures to occur more easily.

Lowering the phosphate intake is one of the options to regulate the phosphate levels in patients with kidney disease.

How can I eat a low-phosphate diet?

Phosphate intake is closely related to the protein intake; that is, protein-rich foods such as dairy products, meat and sausages are also high in phosphate.

Various foods contain additives that contain phosphates. You can find this information on the label of the food in the list of ingredients.

Phosphate cannot be removed from food or is very difficult to remove during preparation, so cooked dishes contain almost as much phosphate as raw products.

Good to know: the nutrition tables always contain the value that is measured in the laboratory and not what the intestine actually absorbs .

The body can only absorb 50 to 60% of the phosphate from foods rich in fiber, in contrast to food with artificial phosphate added. The phosphate from food additives present in a lot of processed foods is almost completely absorbed by the body.

Practical tips:

●    Processed cheese preparations of all kinds (e.g. cooked cheese, cheese spread, processed cheese), powdered milk and condensed milk contain or add a lot of phosphate. You should avoid these foods. 

●    Eat hard or semi-hard cheese only rarely and in small quantities, i.e. not more than 1–2 thin slices (25–50 g) per day.   

●    Choose low-phosphate cheeses such as quark, cream cheese, camembert, brie cheese or mozzarella.      

●    All liquid milk products contain a lot of potassium and phosphate, so do not drink or eat more than 1/8 l milk, buttermilk or yoghurt a day.      

●    Fresh meat is more suitable than processed meat or sausage products such as cured meat, as these often contain phosphate additives.      

●    Ask specifically about sausage without added phosphate in the butcher's shop.      

●    Eat only a small portion of freshly prepared meat (approx. 125 g) a day.      

●    Nuts, almonds and chocolate are rich in phosphate, but you can eat small amounts.  

●    For baking, it is better to use phosphate-free baking powder, (cream of tartar) deer horn salt or baking soda instead of conventional baking powder, as this is very rich in phosphate (1 packet may contain up to
1500mg of phosphate).      

●    Processed foods can contain phosphates as additives, so use fresh, unprocessed foods as much as possible and take a look at the list of ingredients for the products when shopping.

Phosphate additives

Many foods contain additives that contain phosphates. You will find this information on the label of food in the list of ingredients with an E followed by a number (E = Europe). Here are some examples:

E 322, E 338, E 339, E 340, E 341, E 343, E 450 a, E 450 b, E 450 c, E 540, E 543, E 544, E 1410, E 1412, E 1413, E 1414 , E 1442

You should, if possible, avoid these phosphate-containing additives. Please talk to your doctor and nutritionist to learn if you need to and how to better lower your phosphate intake.

A low-sodium diet for chronic kidney disease is defined as 5 to 6 g of table salt (sodium chloride = NaCl) per day. This corresponds with 2000 to 2400 mg or 87 to 105 mmol sodium (Na).

Salt (sodium chloride) is an essential component involved in many important processes in the body. However, we usually tend to consume more salt with our diet than we need. An increased salt consumption not only increases the blood pressure, but also disrupts the equilibrium of water inside the body tissues and outside in the circulation which can lead to accumulation of liquid (also known as edema).

The less table salt you eat, the lower your blood pressure will be and the more effective most antihypertensive drugs will be. Keeping the blood pressure under control helps alleviate the burden on the kidneys and it can slow the decline in the function of the kidneys of patients with kidney disease. 

Tips for a low-salt diet

•    Reduce the consumption of any kind of salt. This includes examples such as: iodized salt, sea salt, herb salt, garlic salt, celery salt, rock salt, Himalayan salt, vegetable bouillon cubes, meat bouillon cubes, etc.

•     Soy sauce is very salty. But there are also soy sauces with reduced salt. Check the labels.

•    Avoid highly salted and processed foods such as processed or ultra processed foods, pickled cucumbers, smoked and cured meat and fish products such as raw ham, anchovies or salted herrings, as well as ready-made meals, ready-made soups, stock cubes and ready-made sauces.

•   There are a lot of options to add flavor to your meals without having to use salt. Adding garlic, lemon or lime juice or any combination of spices you can think of can add lots of flavor to your meals. You won't even miss the salt!

•    It is not recommended that you use salt substitutes such as light salt, half salt or diet salt because these contain a lot of potassium which also needs to also be controled in patients with kidney disease.

•    As always, pay attention to the list of ingredients when possible.

Embracing a low-salt diet is a relatively big challenge and can be difficult to adopt but don't give up: the taste buds of the tongue usually adapt after a week or two.

Just like the sodium in table salt, potassium is an electrolyte. It is crucial for the transmission of nerve impulses that control the muscles, the heart and for the transmission of impulses between the neurons of the brain. High potassium levels cause muscle weakness and in the very worst case can lead to cardiac arrest. Low potassium levels can trigger over-excitability of the muscles and cardiac arrhythmia.

Since the kidneys are the main excretory organ for potassium, when kidney failure or disease occurs, the balance in the potassium levels is impacted.  However, the diseased kidney can appropriately regulate the potassium levels for a very long time. As the kidney function becomes increasingly restricted (when a patient reaches kidney failure), the excretion of potassium also decreases and potassium levels in the blood increase which can be very dangerous and can require immediate medical attention.

Other causes of elevated potassium levels must also be considered:

In addition to diet, there are a number of other causes that make the blood potassium rise, such as: muscle breakdown when you eat too little protein or when acidic metabolic products are not eliminated properly by the kidneys which causes the blood to turn more acidic. This leads to an increase in potassium. Other situations such as vomiting and/or diarrhea lower the amount of potassium in the blood. Some medications can also impact your potassium levels, which is one of the reasons it is important to take your medications as directed and attend your regular check ins with your doctor.

Daily fluid intake is a key issue for every kidney disease patient and for every dialysis patient. If the amount of fluid in the body is too large, the water accumulates in certain tissues and leads to the formation of edema. 

The maximum amount of fluid should not exceed 2-3 liters per day.

The ability of the kidney to excrete water does not stop until the end stages of the disease, when the kidneys have all but completely stopped working. 

In general, the following rule applies to avoid water retention (edema):

The amount of urine excreted during the last 24 hours plus 500 - 800 ml corresponds to the amount you would usually be allowed to drink.

However this is only a guiding principle and the amount of liquid each patient is allowed to drink on a daily basis should be determined individually and adapted to suit the stage of kidney disease the patient is at together with the treating kidney specialist.