There is no single eating plan that is correct for patients with chronic kidney disease (CKD). The doctor must always determine at what stage is the CKD. What patients can and cannot eat may be altered, depending on kidney function and other diseases such as diabetes.
This is why it is so important to consult a dietician who can help you choose the correct type of foods. Making healthy food choices is important especially for people with CKD. A good nutrition will supply energy for daily tasks, prevent infections, build muscle, help maintain a healthy weight and may help the kidney disease from progressing.
Protein is an important nutrient which the body needs to help build muscle, repair tissue and fight infections. People with CKD may need to closely watch their protein intake in order to prevent excessive protein from building up in the blood. It is also important that protein levels are not excessively low.
Animal protein (meat, fish, seafood and eggs) are the easiest source of protein for the human body to absorb. Protein found in grain (beans, peas, chickpeas, lentils, broad beans and whole-wheat cereals) are not so easy for the body to absorb. They should be consumed in groups (e.g. pasta with beans or lentils with rice). A balanced diet should include both types of protein.
A mineral found in many foods and also in table salt. In some CKD patients, it’s also necessary to limit sodium intake. When the kidneys aren’t functioning correctly, sodium can build up in the body. There are some cooking ideas for substituting table salt:
▪ Add aromatic herbs to your dish: coriander, rosemary, thyme (good for meat), mint, bay leaves.
▪ Use fresh lemon or tomato juice for preparing sauces or making a hot pepper sauce.
▪ Add garden-parsley, fennel (for fish sauces), fresh basil or oregano (in pasta), pineapple, green pepper, mushrooms or celery for flavouring some dishes.
▪ As a dressing use olive oil, garlic or aromatic vinegar, oregano.
▪ You can also add thyme, pepper, garlic, onion, mint or bay leaves to fish for flavour.
▪ Spices: saffron (for rice, fish or meat balls), dill (fish sauces, in yoghurt and cucumber sauce as a salad dressing), nutmeg (for mashed potatoes, spinach, eggs or Brussels sprouts), or others: pepper, cinnamon, aniseed, ginger, paprika.
Avoid salty foods: sausages, smoked ham, bacon, hot dogs and other processed meats, salty cheese, powdered milk, canned foods or frozen dinners, fast food, sauces (mayonnaise, mustard, ketchup, soy sauce), stock cubes, salted snacks such as chips and crackers, canned or dehydrated soups.
Read food labels and choose the lower sodium products. In general, per day, one should not ingest more than 2400mg sodium. Avoid using salt substitutes without asking your dietician as some are very high in potassium (another mineral which CKD patients have to reduce).
This important mineral helps your heart and muscles to function. It is therefore necessary to maintain a correct potassium balance in the blood. Some CKD patients need less than others; this will always depend on how well the kidneys are functioning. The patient may be required by his doctor to undergo some simple blood tests in order to check potassium levels. Depending on these results the dietician will create an appropriate food plan for that particular patient.
Large amounts of potassium are found in some foods. Most vegetables and fruit are high in potassium. Food that is low in potassium should be chosen.
There are also some practical ways to reduce potassium in food:
▪ Cooking fresh vegetables and potatoes in a large quantity of water and changing the water twice. Firstly, scald the vegetables in a large quantity of salt-free boiling water for 2-3 minutes. Remove the vegetables from the boiling water and complete the cooking process in another pot of boiling water. Water used for cooking must never be reused as it contains potassium. Peeled potatoes cut in halves can be left soaking overnight to remove excessive potassium. Fried potatoes can be boiled in water first and then fried;
▪ Avoid microwave or pressure cooker.
▪ Fruit can also be boiled and drained. Baked fruit is not in contact with water so there is no potassium loss.
There are some fruits with higher potassium levels than others, e.g.: dried fruit (raisins, dried apricots or figs and others such as nuts, peanuts, almonds, hazel-nuts), and also some fresh fruits: banana, melon, passion fruit, plums, figs, grapes, avocado pears, kiwis, mango, cherries, strawberries.
Pulses, radish, tomatoes, carrot and onion are also high in potassium.
If you need to reduce potassium levels choose low potassium fruit in small quantities (e.g.: 1 small apple or 1 small orange or 1 medium pear or 3 halves of canned peaches (without syrup), 1 thin slice of fresh pineapple or ½ thin slice of water melon) and low potassium vegetables (green beans, leeks, courgettes, red cabbage, aubergine, lettuce, cucumber).
Some patients with advanced CKD have to monitor the ingestion of this mineral, which is found in many foods: dairy products, canned and smoked food, pulses, nuts, chocolate, whole-wheat flour, milk, bread. Most of these foods are also rich in calcium (an important mineral for building strong bones). Therefore, loss of calcium may occur if these foods are inadequately reduced from the diet.
Using milk substitutes without added phosphorus is one way of lowering phosphorus intake in the diet.
Some patients may need a vitamin D supplement to help control the quantity of these minerals in the body.
Some advanced CKD patients must control their daily intake of fluids. To avoid dehydration, it is important to ask your doctor and dietician what is the correct amount in your particular case.
Some CKD patients are vegetarian or have other clinical conditions which will alter some aspects of the diet. Remember that every single CKD patient is different and needs his own personal diet plan which should be adequate for his individual nutritional needs.
By Marina Augusto Estevão
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Marina Augusto Estevão is a dietician at the Hospital Particular do Algarve Group