The National Kidney Foundation and the National Institutes of Health estimates that more than 10% of the population worldwide is affected by chronic kidney disease. It is estimated that in people aged 65-74 years, 1 in 5 men and 1 in 4 women have kidney disease. Kidneys are important to regulate fluid balance and to get rid of waste products, toxins and excess electrolytes (sodium, potassium and phosphate) through urine. Kidneys also produce hormones for red blood cell production and blood pressure control. Damaged kidneys can lead to a variety of problems including fluid retention (swelling), electrolyte buildup, change in hormones, high blood pressure, changes in red blood cells and impaired uptake of calcium resulting in poor bone health. Kidney disease can also contribute to cardiovascular disease.
Acute kidney disease (AKD): A sudden loss of kidney function caused by an illness, injury or toxin. Kidney function may recover.
Chronic kidney disease: (CKD) A long and usually slow deterioration of kidney function.
End stage kidney disease (ESKD): Complete kidney failure- permanent shut down.
Risk factors for developing kidney disease
Diabetes
Hypertension (high blood pressure)
Heart disease
Obesity
Individuals over the age of 60 years
Family history of kidney disease
Acute kidney injury
Smoking
Other conditions such as polycystic kidney disease, lupus, sepsis, HIV…
Kidney disease often goes unnoticed as symptoms are not always present until the more advanced stages of kidney disease.
Symptoms of kidney disease to look out for:
Lack of appetite
Nausea & vomiting
Fatigue & poor concentration
Shortness of breath
Urinating more or less than usual
Painful urination
Foamy urine
Blood in urine
High protein content in urine
Changes in skin – itchy or dry skin
Unexplained weight loss
Swelling in arms and/or legs
Change in the smell of breath
Screening for kidney disease
Screening or testing for kidney disease may involve a combination of blood tests, urine tests and imaging. It is best to consult with your health care provider or general practitioner to identify which screening techniques would be best for you. If kidney problems are identified your general practitioner will refer you to a nephrologist (a medical doctor who specializes in kidney diseases) if necessary.
Bloods may include the following: Creatinine, Glomerular filtration rate (GFR), blood urea nitrogen (BUN) and electrolytes. Urine tests may include a 24 hour urine test to assess urine output and excretion of protein and creatinine, a dipstick test to check for protein and blood and a albumin to creatinine ratio test. Other screening methods may involve an ultrasound, CT scan or a kidney biopsy in some cases. These tests may also be redone to monitor the stage of kidney disease / disease progression.
Kidney Disease stage and eGFR
National Kidney Foundation, 2024. Estimated glomerular filtration rate (eGFR). Available at: https://www.kidney.org/kidney-topics/estimated-glomerular-filtration-rate-egfr [Accessed 10 October 2024].
Treating kidney disease:
With early diagnosis and treatment, it's possible to slow or stop the progression of kidney disease. The treatment for kidney disease typically involves a combination of lifestyle changes, medication and medical interventions. Regular check ups are important to monitory kidney function, electrolyte levels, nutritional status and overall health.
Medical interventions may include a kidney transplant or dialysis. Dialysis is initiated to filter waste and excess fluids from the blood. There are 2 types of dialysis including haemodialysis and peritoneal dialysis.
Haemodialysis: Acts as an artificial kidney by removing extra fluid and waste products from the bloods when kidneys are not able to. This is usually necessary in acute kidney injury and end stage kidney disease. Blood will run through the dialysis machine filter to remove waste products and excess fluid. “Clean” blood is then returned to your body and the dialysis fluid is thrown away.
Peritoneal dialysis: The inside lining of the abdomen is used to filter blood. Cleansing fluid flows into the abdomen and the inner lining, the peritoneum, acts as a filter to remove waste from blood. After some time the fluid (dialysate) is removed from the abdomen and thrown away.
Lifestyle & dietary changes:
Maintaining a healthy body weight and body composition, quitting smoking and alcohol intake and following a kidney friendly diet are essential for the management of kidney disease, even if dialysis is started.
During the progression of chronic kidney disease (CKD), nutritional requirements change significantly. This also depends on medical interventions like dialysis. Because of this, individuals with with kidney disease are at higher risk for nutritional and metabolic abnormalities. The diet for kidney disease should always be individualized by a dietitian. A dietitian will take the following into consideration before planning a kidney friendly diet: The stage of kidney disease, blood results, medical interventions, age, gender, nutritional status, body composition, activity levels and the presence of other chronic conditions.
Most important dietary considerations for managing kidney disease
Limit electrolytes The most important electrolytes to consider when you have kidney disease are sodium, phosphate and potassium. If the kidneys are not secreting excess electrolytes through urine, they will build up in your blood and may lead to serious complications. Your dietitian will adapt your dietary intake of these electrolytes based on your blood results. Remember that this should always be individualized.
Sodium
Elevated sodium levels can lead to fluid retention and high blood pressure which can damage the kidneys, heart brain and eyes. It is recommended to limit your intake of sodium to 1000-4000mg per day if you have kidney damage.
Foods high in sodium to limit or avoid:
Additional tips to lower your sodium intake:
Do not add salt to food when cooking. Rather use alternatives to flavor foods like herbs, pepper, curry, garlic, vinegar, ginger and lemon juice.
Avoid using spices containing salt like barbeque spice, spice for rice, Aromat, garlic and onion salt, meat tenderisers, soup powders and stock cubes.
Do not put salt on the table.
Choose low sodium / sodium free salt and sauces. Do not use potassium containing salt replacements.
Use vegetables instead of sauces when cooking.
Check food labels for sodium content and ingredients like salt, sodium, monosodium glutamate or other sodium additives.
Limit canned foods in salt water or brine, rather use fresh or frozen products. Rinse canned foods well before use.
Avoid processed foods like ready to eat foods, take out foods, pies, sausages, pastries and ham. Rather used unprocessed foods like chicken and fish.
Choose unsalted snacks like plain popcorn and unsalted crackers.
Look for foods labelled as: Sodium free, salt free, very low sodium, low sodium, reduced sodium, no salt added, unsalted.
It is incredibly important to note that the kidney friendly guidelines will remain the same; however, the extent of how strict you have to follow the guidelines will change. For example: Patients with renal failure stage 3 won’t have to be as strict with the guidelines as a patient with renal failure stage 5; patients with end stage kidney failure who refuse dialysis will have to be stricter than a patient on dialysis. It is IMPERATIVE that you see a Dietitian if you are a renal failure patient in order establish the frequency and portion sizes of different food groups allowed. Hence, we do not take any responsibility for patient following this advice without the guidance of a Dietitian.
Potassium
Potassium affects your nerves, muscles and heart and is mostly found in starches, vegetables, fruit and salt substitutes. High blood potassium levels is dangerous to your heart. It is therefore recommended to limit potassium in the diet if your blood potassium levels are above normal. Daily recommended potassium intake: 2000-3000mg/d (this should be individualised).
Potassium content of food:
Tip: Because potassium can dissolve into water, the potassium content of foods (beans, chickpeas, lentils, pumpkin, butternut, potato) can be decreased by doing the following:
Peel, chop and soak potassium foods in water overnight.
Drain the next day and cook in a fresh pot of water before adding to your dish.
How to read nutritional labels for potassium
Phosphate
Phosphate is a mineral important for healthy bone formation. The active form of vitamin D is usually low in individuals with kidney failure. When blood phosphate levels increase, and vitamin D levels decrease the body increases the production of parathyroid hormone (PTH). High PTH levels cause calcium to move from the bones into the blood. As calcium decreases in bones, they become weak and brittle which can lead to renal osteodystrophy. Calcium buildup in the blood can be harmful to the heart and blood vessels.
To prevent mineral and bone disorders it is important to lower your intake of phosphate. A phosphate binder may also be used to decrease phosphate absorption. Discuss this with your health care provider before taking any supplements including phosphate binders, calcium or vitamin D. Daily recommended phosphate intake: 800-1000mg/d (this should be individualised).
Phosphate content of food:
(2 Tables)
Tip: Processed foods often have phosphate added to them. Limit foods that contain the following: phosphate, phosphoric acid, pyrophosphate, polyphosphate and sodium phosphate.
Should protein be avoided if you have kidney disease?
A common misconception about kidney disease is that you can not eat protein at all – this is not true. Protein should however be limited if you have kidney impairment.
Protein is essential for muscles, enzymes, the immune system and hormone production. Protein waste products (creatinine & urea) are usually removed through urine by the kidneys. When kidney disease progress, these byproducts can buildup in the blood, which will further impair organ function. Limiting protein intake may decrease symptoms and delay the need to start dialysis. Remember that reducing protein intake too significantly may result in a poor nutritional status in some individuals. Studies show that protein intake can be reduced to 0.55–0.6 g/kg per day, provided there is sufficient energy intake (e.g., over 30 kcal/kg per day). Adequate calorie consumption is crucial for ensuring protein sparing and optimal metabolic function at this lower protein intake level.
If dialysis is started, protein lost during treatment will have to be replaced – protein requirements are therefore higher compared to those of individuals not on dialysis. If protein is limited too severely, the body may start to break down muscles to get the protein it needs and this can cause extreme fatigue, muscle wasting and an increased risk for infection.
Protein should be individualized according to the stage of kidney disease, blood results and whether dialysis is part of treatment. It is not just the amount of protein that is important, but the type as well. The following should be limited: Proteins high in phosphate, processed meats like russians and viennas, deep fried meats and cold meats like ham. There is insufficient evidence to recommend a particular protein type when it comes to plant vs animal protein.
It is advised to consult a dietitian to determine your specific protein requirements.
What about fluid intake?
Healthy kidneys help to maintain fluid balance in the body. Fluid buildup in the body results in oedema (swelling), weight increase and can put a lot of pressure on the heart and lungs. In the early stages of renal impairment fluids should usually not be limited. Infact adequate fluid intake is very important. As kidney function declines fluid should however be limited according to urine production and the stages of kidney failure. Your nephrologist should determine how much total fluid you should be allowed to consume in a day. Too much or too little fluid could be harmful to the kidneys.
It is important to be aware of how much fluids you are drinking and how much urine you are producing. Your doctor and/or dietitian can help adapt your fluid requirements as needed.
Other important considerations:
Quit smoking
Avoid alcohol
Reduce caffeine intake
Avoid anti-inflammatory medication and pain killers
Maintain a healthy weight and body composition
Stay active
Supplementation may be beneficial (consult your doctor / dietitian)
Importance of monitoring kidney function
It is necessary to go for regular blood tests to monitor kidney function and kidney disease progression. Regular check-ups with a nephrologist and other health care providers (like a dietitian) are also important to manage and monitor kidney disease. It is important to remember that dietary needs can vary significantly depending on the stage of the disease, overall health, and other individual factors. Personalized guidance will not only support kidney function but can also improve quality of life. Consulting a dietitian is invaluable in navigating the complexities of diet for kidney disease in order to create an individualized diet plan.
Click here to check out kidney friendly recipes:
National Kidney Foundation. (n.d.). Renal-friendly recipes.
References:
National Kidney Foundation, 2023. Global facts about kidney disease. Available at: https://www.kidney.org/global-facts-about-kidney-disease [Accessed 15 October 2024].
Kovesdy CP. Epidemiology of chronic kidney disease: an update 2022. Kidney Int Suppl (2011). 2022 Apr;12(1):7-11. doi: 10.1016/j.kisu.2021.11.003. Epub 2022 Mar 18. PMID: 35529086; PMCID: PMC9073222.
Ikizler, T.A., Burrowes, J.D., Byham-Gray, L.D., Campbell, K.L., Carrero, J-J., Chan, W., Fouque, D., Friedman, A.N., Ghaddar, S., Goldstein-Fuchs, D.J., Kaysen, G.A., Kopple, J.D., Teta, D., Wang, A.Y-M., and Cuppari, L., 2020. KDOQI clinical practice guideline for nutrition in CKD: 2020 update. American Journal of Kidney Diseases, 76(3 Suppl 1), pp.S1-S107.
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