Kidney Diet 7 min read·Updated 4 October 2026 Clinician-reviewed

Is Kale Good for Your Kidneys?

A UK Consultant Nephrologist on kale in chronic kidney disease — a green that works well on a renal diet if you boil it and watch the warfarin question.

  • Clinically Reviewed
  • NHS & NICE Aligned
  • UK Evidence-Based
  • Last Reviewed 4 October 2026

Professor Mohammed Mahdi Althaf

Consultant Nephrologist & Acute Physician

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Professor Mohammed Mahdi Althaf

MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN

Consultant Nephrologist & Acute Physician · GMC 7216325

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Direct answer

Kale is low in oxalate and phosphate and moderate in potassium once boiled. An 80 g cooked portion suits most people with CKD. If you take warfarin, keep intake consistent week to week.

Key recommendation: Raw: ~ 450 mg potassium per 100 g; boiling reduces it.

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Quick answer

✓ Best choices

  • Vegetables and lower-potassium fruit at every meal
  • Whole grains: oats, basmati rice, pasta, wholegrain bread
  • Lean protein in modest portions: fish, chicken, eggs, tofu
  • Extra virgin olive oil, herbs and spices for flavour

✓ Foods to limit

  • Added salt and salty sauces
  • Processed meats and foods with phosphate additives (E338–E452)
  • Very large portions of bananas, oranges, potatoes if potassium is rising

Key takeaway

Kale is low in oxalate and phosphate and moderate in potassium once boiled. An 80 g cooked portion suits most people with CKD. If you take warfarin, keep intake consistent week to week.

Who should be cautious

People on dialysis, post-transplant, pregnant or breastfeeding, or taking prescription medication — confirm with your renal team before changes.

Is Kale Good for Your Kidneys?

Boiling: the renal cook's tool

Potassium is water-soluble. Boiling kale in a generous volume of unsalted water and discarding the water removes a useful proportion of it — typically 30–40% for leafy greens. Steaming, stir-frying and microwaving do not achieve the same reduction. If your potassium is restricted, boil; if it is normal, cook however you like.

Warfarin and vitamin K

Kale is one of the richest dietary sources of vitamin K, which opposes warfarin. The clinical advice is not avoidance but stability: eat a similar amount each week so your INR stays predictable. Tell your anticoagulation clinic if you make a big change to your green vegetable intake.

Renal-friendly ways to eat it

  • Boiled kale with garlic, lemon and black pepper — no added salt.
  • Shredded into a soup at the end of cooking (remember the potassium stays in the liquid).
  • Small handful in an omelette with peppers.
  • Avoid: kale crisps (salted), green 'detox' juices which concentrate potassium heavily.
Is Spinach Bad for Your Kidneys?
Related reading: Is Spinach Bad for Your Kidneys?.

Key practical tips

Designed for quick scanning — what to order, what to avoid, sensible portions, common mistakes.

  • Read labels: sodium ≤ 0.3 g per 100 g (low) is the target
  • Cook from scratch when you can — it controls the hidden salt and phosphate
  • Personalise potassium and phosphate targets with your renal dietitian

Clinical guidance

TL;DR summary

Kale is low in oxalate and phosphate and moderate in potassium once boiled. An 80 g cooked portion suits most people with CKD. If you take warfarin, keep intake consistent week to week.

Key takeaways
  • Raw: ~ 450 mg potassium per 100 g; boiling reduces it.
  • 80 g boiled portion: ~ 230 mg potassium.
  • Low oxalate — better than spinach for stone-formers.
  • Very high vitamin K — consistency matters on warfarin.
  • Avoid kale crisps and shop-bought smoothies.
Kidney Diet & Nutrition Considerations

On a kidney-friendly diet, single foods matter less than the overall pattern. Build meals around vegetables, lower-potassium fruit, whole grains, sensible protein and olive oil, and watch the three usual suspects — salt, phosphate additives and oversized portions of very high-potassium foods. Targets are individual and should be confirmed with your renal team.

Foods to prioritise

  • Vegetables and lower-potassium fruit at every meal
  • Whole grains: oats, basmati rice, pasta, wholegrain bread
  • Lean protein in modest portions: fish, chicken, eggs, tofu
  • Extra virgin olive oil, herbs and spices for flavour

Foods to limit

  • Added salt and salty sauces
  • Processed meats and foods with phosphate additives (E338–E452)
  • Very large portions of bananas, oranges, potatoes if potassium is rising

Potassium, phosphate and protein needs vary between individuals — please confirm personal targets with your renal team or dietitian. Browse the Kidney Diet Hub for more guides in this cluster.

Frequently asked questions

Is kale good for kidneys?

Yes, in portion. Cooked kale is moderate in potassium (~ 230 mg per 80 g serving), low in phosphate and low in oxalate compared with spinach — making it one of the better dark leafy greens in CKD.

Is kale high in potassium?

Raw kale is ~ 450 mg per 100 g, but boiling reduces it substantially. An 80 g cooked portion is manageable for most people with CKD.

Should I avoid kale on warfarin?

You do not need to avoid it — you need consistency. Kale is very high in vitamin K, so keep your weekly intake steady rather than swinging between none and large amounts.

Is kale better than spinach in CKD?

For stone-formers, yes — kale is much lower in oxalate. Spinach is also higher in potassium once you account for how much it shrinks when cooked.

What foods are best for kidney health?

A kidney-friendly diet centres on vegetables, lower-potassium fruit (apples, pears, berries), whole grains (oats, basmati rice, pasta), sensible portions of fish, eggs or lean meat, beans and lentils in modest portions, and olive oil as the main cooking fat — broadly a Mediterranean pattern with reduced salt.

Nutritional challenges in kidney disease

Many people living with kidney disease have to limit foods because of potassium, phosphate, diabetes, dialysis, appetite changes or simply the time it takes to cook from scratch every day. That can make it harder to keep daily nutrition balanced — particularly for vitamins and minerals that food alone may not fully cover.

Kidney Vitality is a UK-formulated daily nutritional support product designed by Consultant Nephrologist Professor Mohammed Mahdi Althaf with renal nutrition in mind from the start. It keeps doses moderate, leaves out added potassium, phosphate and magnesium, and avoids megadose vitamin A — sitting alongside a kidney-friendly diet, not replacing it.

Why Kidney Vitality fits this need

Built around UK renal guidance

Aligned with NICE NG203, KDOQI 2020 and BDA renal nutrition guidance.

Designed by a UK Consultant Nephrologist

Formulated and reviewed by Professor Mohammed Mahdi Althaf (GMC 7216325).

Evidence-based by design

No added potassium or phosphate; sensible vitamin doses.

Designed by a UK Consultant Nephrologist

Ready to support your kidney health?

If you have been researching kidney health, supplements, CKD nutrition or kidney-friendly living, Kidney Vitality was developed specifically around those principles by Professor Mohammed Mahdi Althaf (GMC 7216325). Nephrologist Developed Daily Multivitamin.

  • No Added Potassium
  • No Added Phosphorus
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ComparisonKidney VitalityTypical high-street multivitamin
Added potassiumNoneOften included
Added phosphateNoneOften included (E338–E452)
Vitamin A (retinol)No megadoseOften high-dose retinol
Kidney-focused formulationYesNo — general population
Consultant Nephrologist involvementYes (GMC 7216325)No
UK GMP manufacturedYes (BRCGS, NSF GMP)Varies

Food supplement. Not a medicine and not a treatment for kidney disease. Speak with your GP, pharmacist or renal team before starting any new supplement, especially in advanced CKD, on dialysis, post-transplant, pregnant or breastfeeding.

Recommended next

Clinical reviewer

Professor Mohammed Mahdi Althaf

Consultant Nephrologist

Acute Physician

GMC 7216325

View Full Biography

Professor Mohammed Mahdi Althaf is a UK Consultant Nephrologist and Acute Physician with a special interest in chronic kidney disease, AKI prevention and renal nutrition. He combines hospital practice with patient education and clinical guidance review.

View professional profile →
View Credentials
  • MD
  • MSc
  • PgDip (Clin Ed)
  • FRCP
  • FHEA
  • FASN

About this article

Written for UK patients and based on:

  • NICE guidance
  • NHS resources
  • British Dietetic Association guidance
  • Kidney Care UK resources
View methodology

Each article is researched against current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO and KDOQI international guidelines, and the British Dietetic Association Renal Nutrition Group. Drafts are written by the Kidney Vitality editorial team and reviewed by a UK Consultant Nephrologist before publication. Content is reviewed on a rolling basis and updated when guidance changes.

Editorial standards

  • Clinically reviewed
  • NHS-aligned
  • NICE-aligned
  • Evidence-based
  • Reviewed before publication
View full editorial process

Every article is researched and written by the Kidney Vitality editorial team using current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO/KDOQI international guidelines, and British Dietetic Association renal nutrition guidance. Drafts are reviewed for clinical accuracy by Professor Mohammed Mahdi Althaf, MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN (Consultant Nephrologist & Acute Physician, GMC 7216325) before publication. Content is updated when UK guidance changes.

References (4)View Sources
  1. NICE NG203: Chronic kidney disease — assessment and management
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD
  3. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update
  4. British Dietetic Association — Renal Nutrition Group

Medical disclaimer

This content is educational only and does not replace personalised medical advice.

Read full disclaimer

This page is general information, not personal medical advice. If you have chronic kidney disease, are on dialysis, have had a kidney transplant, are pregnant or breastfeeding, or take prescription medication, please confirm any supplement with your GP, pharmacist or renal team before starting.

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