Kidney and bladder health

08 July 2010

Renal nutrition: potassium and sodium

Potassium and sodium recommendations for chronic renal failure patients, provided by the Nutrition Information Centre of the University of Stellenbosch (NICUS).


It is very important to consult with a doctor or dietician to prescribe the correct diet and to incorporate the information obtained from this article into the diet. They will prescribe the amount of potassium and sodium to be consumed per day based on the kidney function, urine output and individual factors such as body weight, activity levels and the background diet.


Potassium is a substance found in food that affects your heartbeat. The unhealthy kidney cannot excrete an excess of potassium in the urine so that it stays behind in the body. Your blood levels of potassium will then rise and it can be dangerous to your heart, even cause death. Potassium is found in many foods, especially fruit, vegetables, milk and certain starches. These foods need to be restricted in the diet to ensure that the potassium in the blood does not increase to dangerous levels.|

Food sources of potassium

Potassium is found particularly in leafy vegetables and most fruit and fruit juice, and in potatoes, especially if they are fried or baked. Usually only 1 portion high potassium starch may be eaten daily but more of the low potassium starches are allowed. A dietician will provide a patient with chronic renal failure with lists of low and high potassium foods (starches, vegetables and fruit).

Food items high in potassium that have to be restricted as prescribed by your dietician

·         Raw vegetables

·         Dried fruit, fruit salad, fruit juice

·         Potato chips (deep fried and crisps), baked potato and sweet potato

·         Tomato puree / juice / sauce

·         Legumes e.g. dried beans, peas, lentils, soya products

·         Nuts and peanuts

·         Brown sugar (not more than 2 teaspoons) and golden syrup (thinly spread)

·         Milk and dairy products e.g. fruit yoghurt and chocolate (do not use more than the daily allowance)

·         Wine, sherry, coffee

·         Salt replacements containing potassium

How to reduce potassium content of vegetables

·         Peel vegetables and cut in smaller pieces.

·         Soak vegetables for about 2 hours in warm water and then drain the vegetables.

·         Afterwards boil the vegetables in water until cooked.

·         Drain before serving. 


The main source of sodium is table salt, or sodium chloride (NaCl). One teaspoon (5 g) of salt contains approximately 2 000 mg of sodium. In patients with chronic renal failure sodium intake should be limited to 1000 – 4000 mg/day depending on their blood pressure and fluid status. This allows only small amounts of salt to be used in cooking, but means limiting very salty foods, and not adding salt to food after it has been cooked.

Salt helps to regulate the body’s fluid balance, but a high salt intake can cause the body to retain water that can lead to high blood pressure. A high blood pressure is unhealthy and can cause damage to the kidney, heart, brain and eyes.

 Guidelines for a low salt diet

Do not add salt to food during the cooking process except for when it is indicated by the dietitian, and do not add extra salt to food at the table. Rather use alternative flavourings that do not contain salt, e.g. herbs, pepper, curry, vinegar, onions, peppers, garlic, ginger, rosemary and lemon juice. 

Avoid salt-containing flavouring agents such as onion salt, celery salt, garlic salt, vegetable salt, barbeque and chicken spices, meat tenderisers, commercial sauces, soups, gravies, and stock cubes. Potassium containing salt replacements (e.g. salt substitutes) should not be used as a replacement since too much potassium can be life threatening to a patient with kidney failure. Check the food labels for forbidden ingredients e.g. salt, sodium, monosodium glutamate (MSG), or any sodium-containing additive. 

Table 1. Practical hints to lower salt intake

Foods with a high salt content

Rather use


Processed foods like viennas, cold meats, ham, hamburger patties or bully beef, beef and pork sausages



Unprocessed chicken, meat or fish, meatballs or other mince dishes, ostrich or venison


 Canned fish, dried fish and smoked fish



Fresh or frozen fish products


Salty spreads like meat and vegetable extracts, fish paste, liver or meat spreads, pâté, cheese spread


Different types of jams and cottage cheese


Cheeses with a high salt content like Blaauwkrantz, Roquefort, Parmesan and Feta cheese


 Cheddar, Gouda, Brie, Mozzarella, or Ricotta in small amounts


Salty snacks like chips, salty biscuits, biltong, dried sausage, salted nuts, salted popcorn, olives or pickles


 Provitas or cream crackers, unsalted nuts, seeds and popcorn

 RenalSmart Nutritional Information System. Low Potassium Diet; Low Sodium Diet. References from the scientific literature used to compile this document are available on request.)

 For further, personalised and more detailed information, please contact NICUS (e-mail or phone 021 933 1408) or contact a dietician registered with the Health Professions Council of South Africa.

- (NICUS, Health24, June 2010)

Read more:

Your guide to renal nutrition


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