Renal diet: eating well with kidney disease

By the DieticiansWorldwide.com editorial team · 17 October 2026 · Clinical nutrition

What a renal diet is, and what it is not

"Renal diet" is not one fixed diet sheet. It is a set of adjustments that change as kidney function changes. Early in chronic kidney disease, the main goals are a heart-healthy, lower-salt pattern that protects blood pressure and slows decline. Later, and especially on dialysis, the priorities shift to controlling potassium, phosphorus and fluid while eating enough protein and energy to avoid malnutrition.

That is why the international guideline from Kidney Disease: Improving Global Outcomes (KDIGO) starts its diet chapter with two practice points rather than a list of banned foods. It advises people with CKD to adopt "healthy and diverse diets with a higher consumption of plant-based foods compared to animal-based foods and a lower consumption of ultraprocessed foods", and to use renal dietitians to tailor sodium, phosphorus, potassium and protein advice to the individual, their stage of CKD and other conditions (KDIGO 2024 CKD guideline, Kidney International).

In the UK, NICE's chronic kidney disease guideline NG203, published in August 2021, says to "offer dietary advice about potassium, phosphate, calorie and salt intake appropriate to the severity of CKD", and that any dietary intervention should come with education, detailed assessment and supervision "to ensure malnutrition is prevented" (NICE NG203).

This article explains the principles for patients, carers and professionals. Your own targets should come from your kidney team, because they depend on your blood results, medicines and treatment.

The renal diet by CKD stage

Protein figures are from KDIGO 2024 and the 2020 KDOQI nutrition guideline as summarised below; restrictions in every row depend on your blood results.

Is a renal diet low protein?

Not usually, and this is where much online advice is out of date. The answer depends on the stage of CKD and on which guideline your team follows, and it is one of the clearest examples of guidelines disagreeing.

• KDIGO (2024) suggests "maintaining a protein intake of 0.8 g/kg body weight/d in adults with CKD G3–G5", a weak recommendation based on low-quality evidence. It advises avoiding high protein intake, above 1.3 g/kg a day, in adults at risk of progression. For people at risk of kidney failure who are "willing and able", it says a very low-protein diet of 0.3 to 0.4 g/kg a day, supplemented with essential amino acids or ketoacid analogues, can be considered under close supervision. It also says not to prescribe low-protein diets to metabolically unstable people, not to restrict protein in children, and to consider higher protein targets for older adults with frailty or sarcopenia.
• KDOQI (2020), from the US National Kidney Foundation and the Academy of Nutrition and Dietetics, recommends 0.55 to 0.6 g/kg a day for metabolically stable adults with CKD stages 3 to 5 without diabetes, or 0.28 to 0.43 g/kg a day with ketoacid analogues; 0.6 to 0.8 g/kg a day in diabetic kidney disease, a range the authors describe as based on expert opinion; and 1.0 to 1.2 g/kg a day for metabolically stable people on haemodialysis or peritoneal dialysis (Kistler and colleagues, Journal of Renal Nutrition, 2021).
• NICE NG203 says: "Do not offer low-protein diets (dietary protein intake less than 0.6 to 0.8 g/kg/day) to adults with CKD."

So a UK patient, a US patient and a patient in a centre following KDIGO could all receive different protein advice at the same stage of CKD. All three agree on two points: very high protein intakes are not helpful in CKD, and any restriction must be supervised so it does not cause malnutrition. On dialysis, protein needs rise because the treatment itself removes amino acids. Our guide to sarcopenia explains why muscle loss is a particular concern in older adults with kidney disease.

Sodium: the one change almost everyone needs

KDIGO suggests that people with CKD keep sodium below 2 g a day, which it equates to less than 90 mmol of sodium or less than 5 g of salt. Lower salt helps control blood pressure, swelling and fluid retention. The exception is the small group with "sodium-wasting" kidney conditions, for whom KDIGO says restriction is usually not appropriate.

The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that too much sodium makes the body hold on to fluid, raising blood pressure and causing swelling that stresses the kidneys and heart (NIDDK, healthy eating for adults with CKD). Most salt comes from bread, processed meat, cheese, sauces, ready meals and takeaways rather than the salt cellar. Our low-sodium diet guide covers label reading in detail.

Avoid salt substitutes unless your team approves them. Many are made from potassium chloride, which can push potassium dangerously high in kidney disease.

Potassium: individual, not automatic

Potassium is where generic "renal diet" sheets cause the most harm. Old handouts often told everyone with kidney disease to avoid bananas, potatoes, tomatoes and most fruit and vegetables. KDIGO now takes a more targeted view. It says limiting foods rich in bioavailable potassium, such as processed foods, is appropriate for people with CKD stages 3 to 5 who have a history of high potassium or during periods when the risk is high. It also notes that other factors, including some medicines, metabolic acidosis, high blood glucose and constipation, "are more likely to explain plasma potassium abnormalities than diet".

KDIGO lists the medicines that commonly raise potassium, including ACE inhibitors, angiotensin receptor blockers, aldosterone antagonists, some diuretics, NSAID painkillers and some immunosuppressants. Many of these protect the kidneys and heart, so the answer is rarely to stop them. Instead, the team adjusts diet, treats constipation or acidosis, or uses potassium-binding medicines.

If your potassium is high

Kidney Care UK says your healthcare team will tell you if you need to make low-potassium choices, and that eating fruit and vegetables remains important, with at least five portions a day (Kidney Care UK, potassium and CKD). Practical steps it and the NIDDK suggest include:

• eat higher-potassium fruit and vegetables, such as plantain, bananas, mangoes, coconut and okra, less often and in smaller amounts;
• drain tinned beans, lentils, fruit and vegetables and discard the liquid; soak and pre-boil dried pulses;
• boil vegetables and potatoes and discard the water, a technique known as leaching;
• keep juices and smoothies small, with Kidney Care UK suggesting no more than 150 ml a day unless your dietitian advises otherwise;
• watch for potassium additives, including potassium chloride, in crisps, processed potato products, processed meats, ready meals and some soft drinks;
• remember portion size: a large serving of a lower-potassium food can contain more potassium than a small serving of a higher-potassium one.

Phosphorus: additives first

High blood phosphorus weakens bones, damages blood vessels and causes itching as CKD advances. The NIDDK says that "phosphorus additives are the primary source of phosphorus for many people", and that the body absorbs more phosphorus from animal foods than from plant foods such as beans and seeds. Its advice is to:

• limit packaged and processed foods and drinks with added phosphorus, such as deli meats and flavoured drinks;
• check ingredient lists for "phosphorus" or words containing "PHOS", such as phosphoric acid and disodium phosphate;
• eat larger portions of fruit and vegetables, which are naturally low in phosphorus, and smaller portions of high-phosphorus foods.

As kidney disease advances, many people are prescribed a phosphate binder, a medicine taken with meals that binds phosphorus in the gut. Binders only work if taken with food, so the timing matters as much as the dose your team prescribes.

Fluid

In early CKD, most people do not need to restrict fluid. On dialysis, and in some people with advanced CKD or heart failure, fluid limits become important, because damaged kidneys cannot remove the excess. The NIDDK says to talk with your healthcare professional about how much liquid you should have each day. Fluid allowances are individual and are usually based on how much urine you still pass and how much weight you gain between dialysis sessions. Foods that are liquid at room temperature, such as soup, ice cream and jelly, usually count towards the total, and cutting salt makes thirst much easier to manage.

What foods should you avoid with kidney disease?

The honest answer is "it depends on your stage and blood results". For most people with CKD, the foods worth limiting are:

1. Very salty foods: processed meats, salted snacks, stock cubes, soy sauce, ready meals and takeaways.
2. Ultra-processed foods with phosphate and potassium additives: processed cheese, cola and other dark soft drinks, some baked goods, reformed meats.
3. Potassium-based salt substitutes, unless your team says otherwise.
4. Herbal and high-dose supplements, which can contain potassium, phosphorus or substances harmful to the kidneys. Always check with your pharmacist.
5. Very high-protein diets and large protein supplements, unless prescribed on dialysis.

If your blood tests show high potassium or phosphorus, your dietitian will add specific foods to limit. If they do not, you may not need those restrictions at all.

What can I eat on dialysis?

More than many people expect. Dialysis changes the goals: protein needs rise, so meat, fish, eggs and other protein foods often feature at every meal, while potassium, phosphorus, salt and fluid are watched more closely. A typical approach includes:

• Protein at each meal: eggs, chicken, fish, lean meat or tofu, in the amounts your dietitian sets for 1.0 to 1.2 g/kg a day or your individual target.
• Energy from lower-potassium, lower-phosphorus starches: white rice, pasta, couscous, white bread, and boiled potatoes if your potassium allows.
• Fruit and vegetables chosen and prepared with potassium in mind: apples, berries, grapes, pineapple, cabbage, green beans, peppers and cauliflower are common lower-potassium choices, though portion size still matters.
• Lower-salt flavour: herbs, spices, garlic, lemon, vinegar and pepper.
• Phosphate binders with meals, if prescribed.
• Planned fluid spread through the day within your allowance.

Peritoneal dialysis and haemodialysis have slightly different rules, because peritoneal dialysis removes potassium more continuously and adds glucose from the dialysis fluid. Your unit's dietitian will adapt the plan to your treatment.

Why DASH and other popular diets need adapting

Many diets marketed for heart health are high in potassium and phosphorus. The DASH diet is a good example: excellent for blood pressure in people with healthy kidneys, but deliberately rich in potassium from fruit, vegetables and dairy. Plant-forward eating, which KDIGO encourages, can still fit CKD, because potassium and phosphorus from whole plant foods are absorbed less than from additives, but the details need tailoring once blood levels start to rise.

Combining restrictive diets is another trap. Someone with CKD and irritable bowel syndrome who is also following a low FODMAP diet, someone with PCOS trying to lose weight, or someone with long-standing restricted eating such as ARFID can end up with very few safe foods and a real risk of malnutrition. People with kidney disease are also at risk of other deficiencies; our guide to B12 deficiency explains why metformin, common in diabetic kidney disease, can lower B12.

How strict does the renal diet need to be?

Strict enough to keep your blood results and fluid in range, and no stricter. Over-restriction is a real and common problem.

• Early CKD (stages 1 to 3a): focus on salt, a healthy plant-forward pattern, blood pressure, blood glucose and weight. Most people do not need potassium or phosphorus restrictions.
• Later CKD (stages 3b to 5): add specific limits only when blood tests show they are needed, and review them regularly. Avoid very high protein, and never start a low-protein plan without supervision.
• Dialysis: the most structured stage, with protein targets, potassium and phosphorus control, binders and a fluid allowance. Even here, the plan should be built around foods you like.

The goal is a diet you can keep for years, not a list of forbidden foods that leaves you hungry, tired and losing weight. You can check how your current eating compares with general guidance using our healthy eating check, but use it alongside, not instead of, renal advice.

Generic diet sheet or an individual plan from a dietitian?

A printed renal diet sheet cannot see your blood results. It cannot know whether your potassium is high because of diet, medicines or constipation, whether you are on haemodialysis or peritoneal dialysis, or whether you are losing muscle. Generic low-potassium handouts have been criticised for disproportionately restricting fruit and vegetables, the very foods KDIGO now encourages.

Both KDIGO and NICE put dietitians at the centre of CKD nutrition care. A renal dietitian will review your blood tests, medicines, stage and treatment, check for malnutrition, translate targets into meals that fit your culture, budget and cooking, and adjust the plan as your kidney function changes. Our guide to working with a dietitian for weight loss is useful if you also need to lose weight before a transplant or to control diabetes. In the UK, "dietitian" is a protected title; the United Kingdom country guide explains how to check registration. If you would like an individual plan, you can book a session with a registered dietitian.

Book a session with a dietitian

A sample day in moderate CKD

This illustration is for an adult with CKD stage 3b, normal potassium and phosphorus, aiming to reduce salt. It is not suitable for dialysis without changes.

• Breakfast: porridge made with water and a little milk, topped with blueberries; tea or coffee.
• Lunch: homemade chicken and salad sandwich on bread with no added salt, with cucumber, lettuce and peppers; an apple.
• Snack: unsalted rice cakes or a small portion of fruit.
• Dinner: baked fish or tofu with herbs and lemon, boiled rice, and green beans and carrots.
• Drinks: water, tea or coffee across the day, unless your team has set a fluid limit.

The practical takeaway

• A renal diet changes with your CKD stage and treatment; there is no single sheet for everyone.
• Cut salt to under 2 g of sodium (5 g of salt) a day, and avoid potassium-based salt substitutes.
• Protein is usually moderate (about 0.8 g/kg) before dialysis and higher on dialysis; never cut it sharply on your own.
• Restrict potassium and phosphorus only when your blood tests show it is needed, starting with processed foods and additives.
• Fluid limits are individual and matter most on dialysis.
• See a renal dietitian for a plan built on your results, medicines and food preferences.