Kidney Diet 7 min read·Updated 22 July 2026 Clinician-reviewed

Are Sardines Good for Your Kidneys?

A UK Consultant Nephrologist on sardines in chronic kidney disease — a low-mercury oily fish with omega-3, vitamin D and edible bones that add natural phosphate.

  • Clinically Reviewed
  • NHS & NICE Aligned
  • UK Evidence-Based
  • Last Reviewed 22 July 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

One drained tin of sardines, 1–2× per week, is a renal-friendly source of omega-3 and protein for most CKD stages. Choose sardines in spring water or olive oil over tomato/brine. Watch portion in advanced CKD on tight phosphate restriction.

Key recommendation: Per 100 g drained: ~ 25 g protein, ~ 397 mg K, ~ 490 mg P, ~ 1.5 g omega-3.

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

One drained tin of sardines, 1–2× per week, is a renal-friendly source of omega-3 and protein for most CKD stages. Choose sardines in spring water or olive oil over tomato/brine. Watch portion in advanced CKD on tight phosphate restriction.

Who should be cautious

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

Are Sardines Good for Your Kidneys?

Why sardines stand out

Sardines are one of the lowest-mercury oily fish, very high in long-chain omega-3 (EPA + DHA), and rich in vitamin D and B12. The FSA encourages 1 portion of oily fish per week (up to 4 for men/post-menopausal women). For CKD, omega-3 supports cardiovascular health — a major driver of mortality in renal patients.

Phosphate from edible bones

Bones add ~ 380–500 mg calcium and ~ 490 mg phosphate per 100 g. In stage 1–3 CKD this is rarely an issue; in stage 4–5 with raised serum phosphate, limit to one tin and don't combine with cheese, processed meat or fortified plant milks at the same meal.

Practical CKD-friendly ideas

  • Sardines on sourdough toast with lemon and parsley.
  • Sardine pasta with garlic, chilli and olive oil.
  • Sardine and cucumber salad with leached new potatoes.
  • Avoid: sardines on toast with melted cheese (P stacking), sardines in tomato sauce on white bread with extra salt.
Is Salmon Good for Your Kidneys?
Related reading: Is Salmon Good 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

One drained tin of sardines, 1–2× per week, is a renal-friendly source of omega-3 and protein for most CKD stages. Choose sardines in spring water or olive oil over tomato/brine. Watch portion in advanced CKD on tight phosphate restriction.

Key takeaways
  • Per 100 g drained: ~ 25 g protein, ~ 397 mg K, ~ 490 mg P, ~ 1.5 g omega-3.
  • Edible bones add calcium and natural phosphate.
  • Choose spring water or olive oil; avoid brine.
  • Moderate purines — care if you have gout.
  • 1–2 tins per week aligns with FSA + renal guidance.
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

Are sardines good for kidneys?

Sardines are a low-mercury oily fish rich in omega-3, vitamin D and protein. The edible bones add calcium and natural phosphate — moderate portions (one tin, 1–2× per week) are renal-friendly for most CKD stages.

Are sardines high in phosphate?

Yes, moderately — the edible soft bones contribute calcium and natural phosphate (~ 400–490 mg per 100 g). On a phosphate-restricted renal diet, keep to one drained tin and don't double-up with cheese or processed meat in the same meal.

What about sodium and purines?

Tinned sardines in tomato sauce can have 400–700 mg sodium per tin — check labels. Sardines are also moderately high in purines, so people with gout should portion carefully.

Sardines vs salmon for CKD?

Salmon: lower P, lower sodium (fresh), best for tight phosphate control. Sardines: higher P from bones but cheaper, shelf-stable, very high omega-3 per pound. Both are renal-friendly in moderation.

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, KDIGO 2024, FSA 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
  • No Added Iron
  • UK Manufactured
  • One capsule daily
  • UK GMP — BRCGS, NSF GMP, Halal
Subscribe & Save — £20.39/monthCheck your current multivitamin

✓ Free UK tracked delivery  ·  ✓ Delivered every 30 days  ·  ✓ Pause or cancel anytime  ·  ✓ Never run out

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.

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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