Potassium and Kidney Disease: Do You Really Need a Low-Potassium Diet?
If you have been diagnosed with chronic kidney disease (CKD), you may have been told that you need to “watch your potassium”.
Search online for a kidney diet and you will quickly find lists telling you to avoid bananas, tomatoes, potatoes, avocado, spinach, legumes, nuts and other supposedly “high-potassium foods”. This can understandably create the impression that having kidney disease automatically means following a low-potassium diet.
For many people with CKD, particularly in the earlier stages, this is not necessarily the case.
Current research suggests that potassium intake should be individualised according to kidney function, blood potassium levels, medications and other clinical factors, rather than routinely restricting nutritious foods simply because they contain potassium (KDIGO, 2024).
There is also increasing recognition that where potassium comes from matters. Potassium contained within whole plant foods may behave quite differently from potassium obtained from meat, dairy products, processed foods and potassium additives.
For someone with early-stage CKD whose blood potassium remains normal, unnecessarily restricting potassium-rich plant foods may remove foods that can support blood pressure, cardiovascular health, gut health and acid-base balance.
Why does potassium become a concern in kidney disease?
Potassium is an essential mineral and electrolyte involved in normal nerve and muscle function, heart rhythm, blood pressure regulation and fluid and electrolyte balance.
The kidneys play a central role in maintaining potassium balance by continually adjusting how much potassium is excreted in the urine.
As kidney function declines, the body's ability to respond to potassium intake can eventually become impaired, increasing the risk of hyperkalaemia — an abnormally high concentration of potassium in the blood.
Significant hyperkalaemia can interfere with the electrical activity of the heart and can become medically dangerous.
However, declining kidney function does not automatically mean potassium will become elevated. The body has compensatory mechanisms for potassium regulation, including increased gastrointestinal potassium excretion as kidney function declines (Palmer and Clegg, 2020).
Many people with mild-to-moderate CKD therefore continue to maintain normal blood potassium levels.
This is why the presence of CKD alone does not tell us whether someone needs a low-potassium diet.
Early kidney disease does not automatically require potassium restriction
The 2024 KDIGO Clinical Practice Guideline recommends a healthy and diverse dietary pattern for people with CKD, with greater consumption of plant-based foods and lower consumption of ultra-processed foods.
Importantly, KDIGO acknowledges that traditional kidney dietary information has heavily emphasised plant foods as potential causes of hyperkalaemia, despite potassium from these foods often being less bioavailable than previously assumed. The guideline recommends an individualised approach to dietary potassium in people with CKD rather than universal restriction (KDIGO, 2024).
This changes the question we should be asking.
Rather than simply:
“Is this food high in potassium?”
a more useful question is:
“Is my blood potassium actually elevated, and where is the potassium in my overall diet coming from?”
Potassium isn't just found in fruit and vegetables
One of the problems with traditional low-potassium food lists is that they tend to focus overwhelmingly on plant foods.
Bananas, tomatoes, potatoes, avocado, spinach, legumes, nuts and dried fruits are commonly highlighted. This can unintentionally give the impression that potassium is predominantly a problem associated with fruit and vegetables.
It isn't.
Meat, poultry, fish, milk and dairy products can also be substantial sources of potassium. Muscle-based animal foods such as meat and poultry are naturally rich in potassium, while milk and yoghurt can also make meaningful contributions to total intake (Carrero et al., 2024).
This can create an interesting imbalance in kidney dietary advice.
Someone may carefully remove bananas, tomatoes and avocado from their diet because they have been told these foods are “too high in potassium”, while continuing to consume substantial amounts of meat and dairy without recognising that these foods are also contributing to their overall potassium load.
And there is another important consideration: not all of that potassium is absorbed equally.
Not all dietary potassium behaves the same way
Food composition tables tell us how much potassium is contained in a food. They don't necessarily tell us how much of that potassium will ultimately be absorbed.
Current evidence suggests approximate potassium absorption rates of:
50–60% from intact plant foods
70–90% from animal-derived foods
around 90% or more from potassium salts used in processed foods (KDIGO, 2024).
The cellular structure and fibre content of whole plant foods appear to limit the amount of potassium released and absorbed during digestion. Animal-derived potassium is generally more readily available, while potassium salts added to processed foods can be particularly well absorbed (Picard, Griffiths, Mager and Richard, 2021; KDIGO, 2024).
This means that two foods containing the same amount of potassium on paper may not necessarily have the same effect on potassium balance.
KDIGO specifically notes that highly processed foods containing potassium additives, meats, dairy products, juices and potassium-chloride salt substitutes can provide more absorbable potassium than many fresh plant foods(KDIGO, 2024).
This is an important shift from the traditional approach of simply categorising foods as “high” or “low” in potassium.
The hidden potassium in processed foods
Potassium additives are another frequently overlooked source.
Potassium compounds are increasingly used in processed foods as preservatives, flavour enhancers, stabilisers and replacements for sodium.
They may be found in some:
processed and enhanced meats
packaged and ultra-processed foods
processed cheeses
sauces and ready-made meals
electrolyte and sports products
low-sodium products
potassium-containing salt substitutes.
Unlike potassium contained within the cellular structure of a whole plant food, potassium additives can be highly bioavailable (Picard et al., 2019).
This creates something of a paradox.
Someone may avoid a fresh tomato because it contains potassium while regularly consuming processed foods containing highly absorbable potassium additives.
This doesn't mean everyone with CKD needs to avoid meat or dairy. It means that when potassium genuinely needs to be reduced, the whole diet needs to be considered rather than automatically targeting fruit and vegetables.
Could potassium-rich plant foods actually be beneficial?
Many foods traditionally labelled “high potassium” are also rich in fibre, vitamins, minerals, polyphenols and other compounds associated with cardiovascular and metabolic health.
There are several reasons these foods may be particularly useful in earlier-stage CKD when potassium handling remains normal.
Blood pressure and cardiovascular health
Potassium plays an important role in blood pressure regulation, partly through its interaction with sodium handling.
Higher-potassium dietary patterns are generally associated with better blood pressure regulation, particularly when sodium intake is high.
This matters in CKD because hypertension is both a major cause and consequence of kidney disease, while cardiovascular disease is a major health risk for people living with CKD.
This does not mean that someone with hyperkalaemia should deliberately increase their potassium intake. It does mean that unnecessarily removing potassium-rich foods from someone who handles potassium normally may remove foods that otherwise form part of a cardioprotective dietary pattern.
Dietary acid load and kidney health
There is another particularly interesting reason fruits and vegetables may be useful in CKD: acid-base balance.
Many fruits and vegetables contain organic anions such as citrate and malate. When metabolised, these provide bicarbonate precursors and contribute to the alkalising effect of plant foods.
By comparison, diets containing larger amounts of animal protein generally produce a greater dietary acid load.
This becomes increasingly relevant as kidney function declines because the kidneys progressively lose some of their capacity to excrete the body's daily acid load.
Research by Goraya and colleagues has investigated increasing base-producing fruits and vegetables as a strategy for reducing dietary acid load in CKD. In people with stage 3 CKD and relatively low serum bicarbonate, increasing fruits and vegetables improved measures of acid-base balance and was associated with preservation of kidney function over three years, similarly to sodium bicarbonate treatment (Goraya et al., 2014).
These studies involved carefully selected and monitored participants and should not be interpreted as evidence that everyone with advanced CKD should substantially increase potassium-rich foods.
They do, however, challenge the assumption that potassium-rich fruits and vegetables are automatically inappropriate in kidney disease.
Fibre, bowel function and potassium
Whole plant foods also provide something meat and dairy do not: dietary fibre.
As kidney function declines, gastrointestinal potassium excretion becomes increasingly important.
Fibre can increase stool bulk and improve intestinal transit, providing another pathway through which potassium can leave the body. Constipation, conversely, can contribute to impaired gastrointestinal potassium elimination and may increase hyperkalaemia risk in susceptible people (Carrero et al., 2024).
This may be another reason why potassium consumed within an intact, fibre-rich plant food does not necessarily behave in the same way as an equivalent quantity of potassium from an additive or more readily absorbed source.
When does potassium actually need to be restricted?
Potassium restriction becomes much more relevant when there is evidence that the body is struggling to maintain blood potassium within a safe range.
The risk generally increases with advanced CKD and kidney failure, but kidney function is only one part of the picture.
Other factors that can contribute to hyperkalaemia include:
certain medications
metabolic acidosis
diabetes
constipation
acute illness
potassium-containing supplements
potassium-containing salt substitutes
highly processed foods containing potassium additives.
Medications such as ACE inhibitors, angiotensin receptor blockers (ARBs) and mineralocorticoid receptor antagonists can increase potassium levels. However, many of these medications provide significant kidney and cardiovascular protection.
Current guidelines therefore recommend addressing correctable causes of hyperkalaemia and considering appropriate potassium-lowering strategies rather than automatically discontinuing beneficial kidney-protective medications (KDIGO, 2024).
If your potassium is high, don't automatically blame the banana
When blood potassium is elevated, dietary modification may certainly be necessary.
But rather than immediately removing a long list of nutritious plant foods, it can be useful to look at the bigger picture.
This might include assessing:
potassium additives in processed foods
potassium-containing salt substitutes
supplements and electrolyte products containing potassium
large amounts of meat or dairy
concentrated potassium sources such as juices, smoothies, sauces and dried fruit
portion sizes and overall potassium intake
constipation
metabolic acidosis
medications affecting potassium handling.
Reviews of potassium management in CKD increasingly question the traditional practice of broadly restricting fruits and vegetables and instead support a more individualised approach that considers potassium source, bioavailability and the other factors affecting serum potassium (Babich, Dupuis, Kalantar-Zadeh and Joshi, 2023; Sumida et al., 2023).
The emerging picture is therefore not that potassium doesn't matter.
It is that potassium is more complicated than a high-versus-low food list.
What about advanced kidney disease and dialysis?
The situation changes as kidney function becomes severely impaired.
People with stage 4 or stage 5 CKD are generally at greater risk of hyperkalaemia, although potassium requirements remain individual.
Dialysis adds another layer of complexity.
For people receiving haemodialysis, potassium accumulates between treatments and is subsequently removed during dialysis. Potassium management therefore needs to take into account blood potassium levels, residual kidney function, dialysis frequency and duration, the interval between treatments, medications, bowel function and dietary intake.
Someone receiving conventional three-times-weekly haemodialysis may therefore have quite different potassium requirements from someone receiving longer or more frequent dialysis.
In advanced kidney disease, dietary potassium should be considered alongside regular blood results and the person's overall treatment rather than based on a generic food list.
The bigger picture
One unintended consequence of traditional kidney diets is that people with CKD can become frightened of eating fruit and vegetables.
Bananas become dangerous. Tomatoes disappear. Avocado is forbidden. Potatoes, legumes and nuts are removed.
Yet meat, dairy products and processed foods may receive far less attention despite also contributing substantial amounts of potassium — sometimes in forms that are more readily absorbed.
The result can be a diet increasingly centred around refined or processed foods that happen to appear on a “low-potassium” list but are not necessarily better for cardiovascular, metabolic or kidney health.
Contemporary kidney nutrition is moving away from this approach.
The goal is not to maximise potassium intake.
Nor is it to minimise potassium intake.
The goal is to maintain blood potassium within a safe range while preserving the nutritional quality of the diet.
For someone with earlier-stage CKD and consistently normal potassium, that may mean continuing to enjoy a diverse range of fruits, vegetables and other minimally processed plant foods.
For someone experiencing recurrent hyperkalaemia, it may mean strategically modifying potassium sources, portions and food preparation while also investigating the other factors contributing to elevated potassium.
The takeaway
Having chronic kidney disease does not automatically mean you need a low-potassium diet.
Potassium restriction becomes most relevant when blood potassium is elevated or trending upwards, kidney function has declined sufficiently to impair potassium handling, or medications and other clinical factors increase the risk of hyperkalaemia.
For many people with earlier-stage CKD and normal potassium levels, unnecessarily avoiding potassium-rich plant foods may remove foods that support blood pressure, cardiovascular health, fibre intake, gut health and acid-base balance.
And when potassium does need attention, it is important not to focus exclusively on fruits and vegetables.
Meat, dairy products, processed foods and particularly potassium additives can also contribute substantially to dietary potassium — and their potassium may be more readily absorbed than potassium contained within intact plant foods.
Rather than asking:
“Which high-potassium foods do I need to avoid?”
a better question is:
“Is my blood potassium actually high, what is contributing to it, and how can I keep it within a safe range without unnecessarily compromising the quality of my diet?”
Kidney nutrition should ultimately be guided by your stage of CKD, blood results, medications and overall clinical picture rather than a generic list of foods labelled “good” or “bad”.
References
Babich, J.S., Dupuis, L., Kalantar-Zadeh, K. and Joshi, S. (2023) ‘Hyperkalemia and plant-based diets in chronic kidney disease’, Advances in Kidney Disease and Health, 30(6), pp. 487–495.
https://doi.org/10.1053/j.akdh.2023.10.001
Carrero, J.J., González-Ortiz, A., Avesani, C.M. et al. (2024) ‘Plant-based diets in patients with chronic kidney disease’, Nature Reviews Nephrology.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10954082/
Goraya, N., Simoni, J., Jo, C.H. and Wesson, D.E. (2014) ‘Treatment of metabolic acidosis in patients with stage 3 chronic kidney disease with fruits and vegetables or oral bicarbonate reduces urine angiotensinogen and preserves glomerular filtration rate’, Kidney International, 86(5), pp. 1031–1038.
https://doi.org/10.1038/ki.2014.83
Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group (2024) ‘KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease’, Kidney International, 105(Suppl. 4S), pp. S117–S314.
https://kdigo.org/wp-content/uploads/2024/03/KDIGO-2024-CKD-Guideline.pdf
Palmer, B.F. and Clegg, D.J. (2020) ‘Potassium homeostasis, chronic kidney disease, and the plant-enriched diets’, Kidney360, 1(1), pp. 65–71.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8808484/
Picard, K., Barreto Silva, M.I., Mager, D. and Richard, C. (2019) ‘Potassium additives and bioavailability: Are we missing something in hyperkalemia management?’, Journal of Renal Nutrition, 29(4), pp. 350–353.
https://doi.org/10.1053/j.jrn.2018.10.003
Picard, K., Griffiths, M., Mager, D.R. and Richard, C. (2021) ‘Handouts for low-potassium diets disproportionately restrict fruits and vegetables’, Journal of Renal Nutrition, 31, pp. 210–214.
https://doi.org/10.1053/j.jrn.2020.07.001
Sumida, K., Biruete, A., Kistler, B.M. et al. (2023) ‘New insights into dietary approaches to potassium management in chronic kidney disease’, Journal of Renal Nutrition, 33(6S), pp. S6–S12.
https://doi.org/10.1053/j.jrn.2022.12.003