Phosphorus and Kidney Disease: Do You Really Need a Low-Phosphorus Diet?
Phosphorus is one of the nutrients most commonly restricted on a traditional ‘kidney diet’.
People diagnosed with chronic kidney disease (CKD) are often given lists telling them to avoid dairy products, nuts, seeds, legumes, whole grains and other foods because they contain phosphorus.
But, much like potassium, phosphorus is more complicated than simply categorising foods as ‘high’ or ‘low’.
The amount of phosphorus contained in a food does not necessarily tell us how much the body will absorb. Phosphorus from plant foods, animal foods and phosphate additives behaves quite differently, and the need for restriction changes substantially according to kidney function, blood results and whether someone is receiving dialysis.
For someone with earlier-stage CKD and normal phosphate regulation, aggressively restricting nutritious phosphorus-containing foods may be unnecessary.
For someone with advanced CKD, persistently elevated serum phosphate or CKD-mineral and bone disorder (CKD-MBD), phosphorus management can become considerably more important.
The aim should therefore not simply be to eat as little phosphorus as possible.
It is to understand where phosphorus is coming from, how readily it is absorbed and whether phosphorus actually needs to be restricted in the individual person.
Why Does Phosphorus Matter in Kidney Disease?
Phosphorus is an essential mineral involved in energy production, cell membranes, DNA, acid–base regulation and normal muscle and nerve function.
Most phosphorus is stored in bones and teeth.
The kidneys play an important role in maintaining phosphorus balance by eliminating excess phosphate through the urine. As kidney function declines, fewer functioning nephrons remain available to excrete the phosphorus absorbed from food.
The body initially compensates for this surprisingly well.
Hormones including fibroblast growth factor 23 (FGF23) and parathyroid hormone (PTH) increase phosphate excretion through the remaining functioning nephrons. FGF23 also reduces production of active vitamin D, which lowers intestinal phosphate absorption.
These adaptations can keep serum phosphate within the normal laboratory range for a considerable period, even as kidney function declines (KDIGO CKD-MBD Work Group, 2017; Cupisti et al., 2025).
Eventually, however, phosphate regulation may become more difficult. Serum phosphate can rise, PTH may increase further and disturbances involving phosphate, calcium, vitamin D and bone metabolism can contribute to CKD-MBD.
Importantly, a normal serum phosphate result in earlier CKD does not necessarily mean phosphorus physiology is completely unchanged.
However, this does not mean everyone with early CKD should automatically follow a low-phosphorus diet.
Current KDIGO guidance recommends that phosphate-lowering treatment is principally based on progressively or persistently elevated serum phosphate, rather than attempting to lower phosphate in everyone with CKD (KDIGO CKD-MBD Work Group, 2017).
KDOQI similarly recommends individualising dietary phosphorus according to serum phosphate and specifically considering the source and bioavailability of dietary phosphorus (Ikizler et al., 2020).
Not All Dietary Phosphorus Is Absorbed Equally
This is probably the most important practical concept in phosphorus management.
A food composition database may tell us how many milligrams of phosphorus a food contains, but the kidneys ultimately have to manage the phosphorus that is actually absorbed.
Dietary phosphorus can broadly be divided into:
inorganic phosphorus from phosphate additives
organic phosphorus from animal foods
organic phosphorus from plant foods.
Their bioavailability can differ considerably.
This is one reason contemporary renal nutrition is moving away from simply telling people to avoid every food that appears on a ‘high-phosphorus’ list (Biruete et al., 2023).
Phosphate Additives Are Usually the First Place to Look
Phosphate additives are widely used in food processing to improve texture, retain moisture, stabilise foods and extend shelf life.
They may occur in:
processed and deli meats
sausages and some bacon products
marinated or ‘enhanced’ meats and poultry
processed cheeses
cola drinks
commercial baked goods
packaged snack foods
convenience foods and sauces.
Not every product in these categories contains added phosphate, which is why checking the ingredient list is more useful than avoiding whole food categories.
In Australia, phosphate-containing additives may appear under names or additive numbers including:
phosphoric acid — 338
sodium phosphates — 339
potassium phosphates — 340
calcium phosphates — 341
pyrophosphates — 450
triphosphates — 451
polyphosphates — 452.
Ingredients containing words such as phosphate, phosphoric, polyphosphate or pyrophosphate are therefore worth looking for.
The important distinction is that phosphorus from inorganic phosphate additives is generally absorbed much more readily than naturally occurring phosphorus from whole foods (Ikizler et al., 2020; Fishbane and Nigwekar, 2021).
This makes phosphate additives particularly relevant in people struggling to control serum phosphate.
A randomised controlled trial in people receiving haemodialysis found that teaching participants to identify and avoid foods containing phosphate additives produced a greater reduction in serum phosphate than usual care (Sullivan et al., 2009).
That is a very different intervention from simply telling someone to stop eating nuts, legumes or whole grains.
What About Phosphorus From Animal Foods?
Animal foods naturally contain phosphorus as part of proteins and other cellular structures.
Important sources include:
meat
poultry
fish and seafood
eggs
milk
yoghurt
cheese.
Phosphorus from animal foods is generally more bioavailable than phosphorus bound within intact plant foods.
That does not mean animal foods are inherently harmful in CKD.
Protein requirements remain important, particularly in advanced disease and dialysis. The appropriate amount and source of protein needs to be considered alongside serum phosphate, CKD stage, nutritional status and whether dialysis is being undertaken.
There is also an important difference between a fresh protein food and the same food with phosphate additives.
Fresh chicken, for example, is nutritionally different from processed or marinated chicken containing added phosphate salts.
For people who need tighter phosphorus control, reducing processed sources may therefore be more useful than unnecessarily reducing all protein foods.
Plant Phosphorus Is Generally Less Bioavailable
Many plant foods contain substantial amounts of phosphorus when viewed in a nutrient database.
Examples include:
legumes
lentils
nuts
seeds
whole grains
soy foods.
This is one reason traditional renal diets have often restricted them.
However, much of the phosphorus in plants is stored as phytate.
Humans have limited ability to digest phytate because we produce very little of the enzyme phytase. As a result, a smaller proportion of phosphorus from many intact plant foods is absorbed compared with phosphorus from animal foods or phosphate additives (Ikizler et al., 2020; Biruete et al., 2023).
This distinction has also been demonstrated experimentally.
In a small controlled crossover study involving people with CKD, Moe and colleagues compared vegetarian and meat-based diets containing similar amounts of protein and phosphorus. After seven days, the vegetarian diet resulted in lower serum phosphorus and lower FGF23 (Moe et al., 2011).
The study was small, so it should not be interpreted as evidence that plant phosphorus can never contribute to elevated phosphate.
It does, however, demonstrate an important principle:
the phosphorus content listed for a food does not necessarily predict its physiological phosphorus load.
Food processing can also change this picture. Grinding, fermentation and other processing techniques may increase phosphorus availability, while processed plant-based foods can also contain phosphate additives.
So whole lentils or a handful of nuts is not metabolically equivalent to an ultra-processed plant-based product containing added phosphates simply because both are ‘plant based’.
Phosphorus Restriction Should Not Create Malnutrition
One of the difficulties with restrictive renal diets is that phosphorus-containing foods often provide other important nutrients.
Depending on the food, these may include:
protein
calcium
fibre
magnesium
essential fatty acids
vitamins and other micronutrients.
Someone who simultaneously removes dairy products, legumes, nuts, seeds, whole grains and substantial amounts of protein may certainly reduce phosphorus intake.
But they may also substantially reduce the nutritional quality of their diet.
This becomes particularly concerning in advanced CKD when appetite, weight and muscle mass may already be declining.
It is even more relevant during dialysis, when protein requirements increase.
The challenge is therefore often to reduce the amount of absorbable phosphorus without unnecessarily reducing useful protein and overall nutritional intake.
This may mean prioritising minimally processed foods, reducing phosphate additives and considering the phosphorus-to-protein profile of different protein sources.
Phosphorus Becomes More Important in Advanced CKD
As kidney function declines towards stages 4 and 5, phosphate regulation often becomes more difficult.
At this stage, phosphorus management may need to become more deliberate, particularly where blood tests show:
rising serum phosphate
elevated PTH
abnormalities in calcium
changes in alkaline phosphatase
abnormalities in vitamin D metabolism
other evidence of CKD-MBD.
Some people may respond adequately to reducing phosphate additives and modifying food choices.
Others may require more substantial dietary phosphorus restriction.
Phosphate binders may also be prescribed in more advanced CKD or dialysis. These medications bind dietary phosphate in the gastrointestinal tract, reducing the amount available for absorption.
Their effectiveness depends considerably on taking them correctly in relation to meals, so dietary management and phosphate-binder therapy need to work together.
Dialysis Changes the Picture Again
Once dialysis begins, phosphorus can become particularly challenging.
Haemodialysis removes phosphate, but conventional dialysis may not remove enough to compensate for all of the phosphorus absorbed between treatments (Fishbane and Nigwekar, 2021).
At the same time, protein requirements increase.
For people receiving maintenance haemodialysis, protein intake of around 1.0–1.2 g/kg/day may be recommended to help maintain nutritional status (Ikizler et al., 2020).
This creates an obvious tension: many protein foods also contain phosphorus.
For this reason, phosphorus control during dialysis should not simply mean eating progressively less protein.
More useful strategies can include:
avoiding phosphate additives
choosing less processed protein sources
considering phosphorus bioavailability
maintaining adequate protein intake
using phosphate binders correctly where prescribed
reviewing dialysis adequacy.
People receiving frequent, extended or nocturnal dialysis may also have different requirements from those receiving conventional dialysis, so dietary advice should remain individualised.
Kidney Transplantation Can Produce the Opposite Problem
Phosphorus requirements can change again after kidney transplantation.
In the early post-transplant period, low serum phosphate is relatively common.
Persistently elevated FGF23 and PTH from the period of advanced CKD can continue promoting urinary phosphate loss even after kidney filtration has improved.
As a result, someone who previously required significant phosphorus restriction during dialysis may temporarily need their dietary phosphorus intake liberalised after transplantation (Ikizler et al., 2020).
This is another good example of why a ‘kidney diet’ cannot remain static.
What was appropriate before transplantation may become inappropriate afterwards.
So, Who Actually Needs a Low-Phosphorus Diet?
Rather than assuming everyone with CKD needs phosphorus restriction, I would consider:
CKD stage and trajectory
serum phosphate and whether it is rising over time
calcium and PTH
CKD-MBD
overall protein intake
nutritional status
exposure to phosphate additives
the balance between plant and animal foods
whether the person is receiving dialysis
phosphate-binder use
whether they have received a kidney transplant.
Looking only at the phosphorus content of individual foods misses much of this context.
A More Practical Approach to Phosphorus
For many people with CKD, a useful hierarchy is:
First, reduce unnecessary phosphate additives.
This can reduce a highly absorbable source of phosphorus without compromising dietary quality.
Second, consider overall food quality.
A diet based predominantly on minimally processed foods will generally contain fewer inorganic phosphate additives than one dominated by processed meats, takeaway foods and packaged products.
Third, consider phosphorus bioavailability.
Phosphorus from intact plant foods is generally less readily absorbed than phosphorus from animal foods, while inorganic phosphate additives are particularly bioavailable.
Fourth, match phosphorus restriction to the actual clinical situation.
If serum phosphate is normal and CKD is relatively early, there may be little reason to remove a wide range of nutritious whole foods simply because they contain phosphorus.
If phosphate is persistently elevated in advanced CKD or dialysis, phosphorus restriction may need to become progressively more targeted.
Finally, protect nutritional adequacy.
Phosphorus control should not come at the cost of inadequate protein, energy, fibre or micronutrient intake.
There Is No Single ‘Low-Phosphorus Kidney Diet’
Phosphorus is important in kidney disease, particularly as CKD becomes more advanced.
But the traditional idea that everyone with kidney disease simply needs to avoid ‘high-phosphorus foods’ is increasingly difficult to justify.
What matters is not just how much phosphorus a food contains.
It is how much is absorbed, where it comes from, the person’s kidney function, their blood results, their nutritional requirements and whether they are receiving dialysis.
For many people, particularly in earlier CKD, the first priority may be reducing highly processed foods containing phosphate additives rather than unnecessarily restricting nutritious whole foods.
As kidney function declines, phosphorus management may become considerably more important and may need to be integrated with protein targets, phosphate binders and dialysis.
The goal is therefore not to create the lowest-phosphorus diet possible.
It is to create the least restrictive diet that maintains appropriate phosphate control while preserving overall nutritional quality.
References
Biruete, A., Hill Gallant, K.M., Lloyd, L., Meade, A., Moe, S.M., St-Jules, D.E. and Kistler, B.M. (2023) ‘“Phos”tering a clear message: the evolution of dietary phosphorus management in chronic kidney disease’, Journal of Renal Nutrition, 33(6 Suppl), pp. S13–S20. View article
Cupisti, A., Giannese, D., Cozzolino, M., Panichi, V., D’Alessandro, C. and Gallieni, M. (2025) ‘Dietary phosphorus and metabolic health in CKD and ESKD’, Clinical Journal of the American Society of Nephrology, 20(9), pp. 1289–1298. View article
Fishbane, S.N. and Nigwekar, S. (2021) ‘Phosphate absorption and hyperphosphatemia management in kidney disease: a physiology-based review’, Kidney Medicine, 3(6), pp. 1057–1064. View article
Food Standards Australia New Zealand (FSANZ) (2026) Australia New Zealand Food Standards Code – Schedule 15: Substances that may be used as food additives. View legislation
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. View guideline
Kidney Disease: Improving Global Outcomes (KDIGO) CKD-MBD Update Work Group (2017) ‘KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease–Mineral and Bone Disorder (CKD-MBD)’, Kidney International Supplements, 7(1), pp. 1–59. View guideline
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(4S), pp. S117–S314. View guideline
Moe, S.M., Zidehsarai, M.P., Chambers, M.A., Jackman, L.A., Radcliffe, J.S., Trevino, L.L., Donahue, S.E. and Asplin, J.R. (2011) ‘Vegetarian compared with meat dietary protein source and phosphorus homeostasis in chronic kidney disease’, Clinical Journal of the American Society of Nephrology, 6(2), pp. 257–264. View article
Sullivan, C., Sayre, S.S., Leon, J.B., Machekano, R., Love, T.E., Porter, D., Marbury, M. and Sehgal, A.R. (2009) ‘Effect of food additives on hyperphosphatemia among patients with end-stage renal disease: a randomized controlled trial’, JAMA, 301(6), pp. 629–635. View article
This article provides general educational information and is not intended to replace individual medical or nutritional assessment. Dietary requirements in chronic kidney disease can change substantially according to kidney function, pathology results, medications, nutritional status and treatment stage.