Jul 5, 2021 | Nutrition

A Fine Balance

– Kim Rutgers, Registered Dietitian (SA),
Today’s eating habits differ drastically from those of yesteryear and, while opting for healthy food is important for us all, it’s even more crucial for sufferers of kidney disease. Here’s why.
The main nutrients of interest that play havoc in the system are phosphate, potassium and sodium.

Most of us know that the main function of the kidneys is to remove toxins, waste products and excess fluid from the body by flushing them out though the urine. Apart from keeping a stable water balance in the body, they’re also responsible for controlling electrolyte and acid-base balances.

In our westernised diets, the tendency towards eating processed foods has given rise to chronic diseases of lifestyle, including kidneyrelated ailments. Kidney disease and kidney (renal) failure is rising globally, with obesity and diabetes mellitus posing the biggest risk factors. Other contributors include hypertension, chronic urinary-tract infections and sepsis, tumours, and family history. Despite the fact that obesity leads to kidney disease, once the condition progresses, about 20-60% of patients may become malnourished. So it’s important that kidney-disease patients strive for an optimal nutrition status in the event that dialysis is initiated. Secondary conditions that are associated with kidney failure include mineral bone disease, cardiovascular disease, anaemia and diabetes.

Electrolyte excess

In renal failure, one size doesn’t always fit all. Many aspects of a patient’s condition need to be examined by a health professional, but treating kidney disease includes certain changes in eating habits in order to reduce strain on the kidneys.
The main nutrients of interest that play havoc with the system are phosphate, potassium and sodium – diseased kidneys can’t eliminate excesses in these electrolytes.
Protein intake should be limited, as the kidneys have to work much harder to remove protein waste, and it begins to build up in the blood.
Fluid intake may also be curtailed, as poorly functioning kidneys can cause fluid retention. All of these restrictions should be discussed with your doctor


Restricting phosphate early on in kidney disease may offer some protection against renal bone disease. Being conservative when it comes to eating phosphate-rich foods may also slow down the progression of the disease, and ease symptoms. Foods that contain phosphate include all meat and fish products, some carbonated drinks, dairy products, and beans and peas.


With the help of blood tests, medical doctors will be able to establish if your potassium levels are higher than the normal range. If so, strict restrictions must be put in place, and a dietitian will help you plan and navigate your food choices, so as not to increase potassium levels. Foods rich in potassium include some vegetables – spinach, mushrooms, beetroot, broccoli, carrots, tomato, and potatoes (if not soaked in water overnight before use) – and some fruits, such as apricot, banana, avocado, melon, kiwi and mango. Drinks to limit include fresh fruit juices, coffee, hot chocolate, malted drinks and cordials.
There are ways to assist with lowering potassium in foods: boil them in large volumes of water, soak legumes overnight and discard the water, soak chopped potatoes in water overnight and discard the water before use, and parboil veggies before adding them to stews and curries. Avoid
microwave cooking and pressure cooking (the nutrients may stay in the dish) and always be mindful of portion size. .


The kidneys acts as filters to excrete excess fluid. Sodium and potassium aid the body with fluid balance, but a diet high in sodium (from salt) will alter your fluid balance, resulting in fluid overload. It may also cause reduced kidney function and the removal of less water. More fluid and less excretion will equal high blood pressure, which impacts the kidneys and causes damage (sometimes irreversible).
From a nutritional point of view, it’s best to keep your daily salt intake below the recommendations of the World Health Organization and The Heart and Stroke Foundation of South Africa: less than one teaspoon of salt a day, which equates to 5g. You can do this by cutting out processed meats (such as polony and viennas), instant noodles, sausages and other processed foods.

Because diseases differ from person to person, be sure to get professional support by always consulting your doctor.