Eating With Chronic Kidney Disease: A Family Guide

Why diet matters in kidney disease

Healthy kidneys filter waste, balance salts and water, control blood pressure and activate vitamin D. As function falls, waste products (urea), potassium, phosphorus and fluid build up, blood pressure rises and bones weaken. Diet can ease the load on the kidneys, control blood pressure and blood salts, slow progression in some cases and reduce symptoms such as swelling, itching and nausea. But too much restriction can cause malnutrition and muscle loss, which worsen outcomes. See chronic kidney disease: a home care guide for the wider picture.

Know the stage and the numbers

Kidney function is graded by the estimated glomerular filtration rate (eGFR) into stages 1 to 5. Dietary needs differ:

• Early stages (1 to 2): general healthy eating, blood pressure and sugar control, less salt.
• Stages 3 to 4: attention to salt, protein amount, and sometimes potassium and phosphorus, as the blood tests show.
• Stage 5 and dialysis: specific limits on potassium, phosphorus and fluid; protein needs often increase on dialysis.
• After a transplant: different advice again.

Ask for your parent's latest blood results (creatinine, eGFR, potassium, phosphorus, calcium, haemoglobin, albumin, bicarbonate, sugar) and ask the nephrologist or dietician which nutrients need limiting.

Salt (sodium)

Salt raises blood pressure, causes swelling and thirst, and harms the kidneys. Almost all CKD patients benefit from less salt. The World Health Organization recommends less than 5 grams of salt (about one level teaspoon) a day for adults; many kidney doctors advise less.

• Cook with less salt; add only at the end, use lemon, herbs, ginger, garlic, cumin, coriander, mint, curry leaves, tamarind and mild spices for flavour.
• Limit pickles, papad, chutneys, namkeen, chips, salted nuts, processed cheese, instant noodles, ready-made sauces, soy sauce, canned and packaged foods, sauces, stock cubes and salted snacks.
• Avoid salt substitutes (potassium chloride) unless the doctor agrees, since they can cause dangerous potassium rise.
• Read labels for sodium; see how to read a supplement label for label skills.
• Dining out and festivals: choose simpler dishes.

See eating for heart health after 60.

Protein

• Early CKD (not on dialysis): doctors may advise a moderate protein intake (often around 0.6 to 0.8 grams per kilogram of body weight a day, in selected people and under supervision) to reduce kidney workload, but very low protein diets are risky in older, frail people and can cause malnutrition. Do not restrict protein on your own, and do not start extra protein without advice.
• Dialysis: protein needs rise because dialysis removes protein; typical targets are around 1.0 to 1.2 grams per kilogram or higher, as the dietician sets.
• Quality: high-quality protein such as egg whites, fish, chicken, and in moderate amounts dairy and paneer; plant proteins (dal, soya) are also fine in appropriate amounts, with attention to phosphorus and potassium content.
• Avoid protein powders and high-protein supplements unless the nephrologist or dietician approves; see protein powder for older adults: who needs it and how to choose and how much protein do older adults need.
• Balance with calories: enough energy from carbohydrates and healthy fats stops the body from burning protein.

Potassium

Potassium helps nerves and muscles, but when kidneys fail, it can build up and cause dangerous heart rhythm problems. Not everyone with CKD needs a low-potassium diet; it depends on blood potassium levels and medicines (some blood pressure medicines raise potassium). Do not restrict or increase potassium foods without the blood test and doctor's advice.

When limits are advised:

• Higher-potassium foods to limit: bananas, oranges and orange juice, coconut water, mangoes, papaya in large portions, melon, tomatoes and tomato sauce, potatoes, sweet potatoes, spinach and other leafy greens in large quantities, mushrooms, dried fruits, nuts, beans and lentils in large quantities, chocolate, salt substitutes and some herbal and "health" drinks.
• Lower-potassium options: apple, pear, guava, pineapple, grapes, berries, watermelon in small amounts, cabbage, cauliflower, bottle gourd, ridge gourd, brinjal, onion, cucumber, carrot in moderation, white rice, white bread, rotis (portions).
• Leaching vegetables: peeling, cutting small, soaking in plenty of warm water for several hours, then discarding the water and boiling in fresh water reduces potassium in potatoes and some vegetables; the dietician can show how, and note that it is not perfect.
• Portion matters more than the list: a small piece of a "high" fruit may be fine.
• Dals and legumes: often limited in amounts; the dietician decides portion sizes.

Phosphorus

High phosphorus weakens bones, calcifies blood vessels and causes itching. Limits start in later stages and with dialysis.

• High-phosphorus foods: dairy (milk, curd, paneer, cheese) in large amounts, nuts and seeds, dals and pulses in large amounts, whole grains and bran, dark colas, processed meats and cheese, packaged and fast foods with phosphate additives (check labels for "phos").
• Phosphate binders: tablets prescribed by the nephrologist, taken with meals, to bind phosphorus; follow exactly; do not skip or double.
• Natural phosphorus in plant foods is absorbed less than that in additives, so avoid processed foods first.

Fluid

• Early stages: often no fluid restriction; adequate drinking protects kidneys; see hydration for older adults: how much and how to remember.
• Advanced CKD with swelling, or dialysis: fluid may be limited, typically by adding the urine passed per day to a set amount, as advised.
• Count all fluids: water, tea, milk, buttermilk, soup, dal, ice, fruit, kulfi, kheer and gravy.
• Tips: use a marked jug for the daily allowance; sip from small cups; suck ice chips or sugar-free sweets for thirst; avoid salty foods; rinse the mouth; weigh daily to monitor fluid gain, as the dialysis team advises; see daily weights in heart failure: why and how for method.
• Do not restrict fluids unless advised; dehydration harms kidneys.

Calories, malnutrition and appetite

Many older CKD patients lose weight because of poor appetite, nausea, taste changes, dietary restrictions and dialysis. Malnutrition predicts worse outcomes, so ensure enough calories: healthy fats (oils in cooking), rice, rotis, suitable sweets in small amounts, and, if advised, renal-specific supplements. See malnutrition in older adults: signs and prevention and loss of appetite in older adults: causes and practical fixes. With diabetes, balance sugar control with adequate calories; see eating for diabetes after 60.

Sample ideas (for the dietician to adapt)

A day might include idli or poha with vegetables at breakfast, a small katori of white rice or two rotis with a modest portion of dal and low-potassium vegetables (cabbage, cauliflower, bottle gourd) at lunch, an apple or guava as a snack, and a lighter version at dinner, all cooked with little salt and measured oil.

Supplements, herbs and remedies: be very careful

• Do not take herbal, Ayurvedic or traditional remedies, "kidney cleansing" products or supplements without the nephrologist's approval. Some contain heavy metals (lead, mercury, arsenic), aristolochic acid or other kidney toxins; others are high in potassium or interact with medicines. Many unregulated products have caused kidney damage.
• Vitamins and minerals: ordinary multivitamins may contain vitamin A, potassium, magnesium and other minerals that accumulate; kidney-specific vitamins exist; see multivitamins for older adults: helpful or wasteful? and supplements and medicine interactions: a safety guide.
• Calcium and vitamin D: may be prescribed in specific forms; do not self-start; see calcium and vitamin D after 60: doses, food and sun.
• Protein powders, amino acid supplements, creatine and body-building products: avoid.
• Magnesium and aluminium antacids and laxatives: avoid or use only as advised.
• Painkillers: NSAIDs (ibuprofen, diclofenac, naproxen) can damage the kidneys; avoid unless the doctor approves; see painkillers and older adults.
• Potassium supplements and salt substitutes: avoid.
• Always show the nephrologist and pharmacist every product, and never stop prescribed medicines for kidney, heart, blood pressure, diabetes or bone problems because of a supplement.

Dialysis diets

People on haemodialysis or peritoneal dialysis generally need:

• More protein than before dialysis.
• Potassium, phosphorus, salt and fluid limits as set by the team.
• Enough calories.
• Possible vitamin and mineral supplements designed for dialysis.
• Attention to blood sugar if diabetic.
• Timing: eating well before and after dialysis; carrying snacks to sessions only if allowed.

The renal dietician in the dialysis unit should provide an individual plan; see living with dialysis: routines, travel and support.

Warning signs: seek urgent help

• Muscle weakness, palpitations, a slow or irregular pulse, chest pain, fainting (possible high potassium): call 112.
• Severe breathlessness, swelling, rapid weight gain (fluid overload); see when breathlessness is an emergency.
• Passing very little urine or none, nausea, vomiting, confusion, drowsiness, severe itching, or a metallic taste.
• Severe vomiting or diarrhoea, with inability to drink; see diarrhoea and dehydration in older adults.
• Fever, back pain or burning urine.

When to ask a professional

Ask the nephrologist for the stage, targets and which nutrients to limit. Ask a renal dietician for a personalised, culturally suited meal plan with portions. Ask a pharmacist about medicines and supplements. Never start protein powders, herbal products or salt substitutes without approval. Seek urgent help for weakness, palpitations, severe breathlessness, no urine or confusion.