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

Is Tuna Good for Your Kidneys?

A UK Consultant Nephrologist on tuna in chronic kidney disease — a lean, affordable protein when you choose the right tin and watch sodium and mercury.

  • 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

Plain tinned tuna in spring water (drained) is one of the most renal-friendly convenience proteins. Avoid tuna in brine, flavoured pouches and tuna mayonnaise sandwiches from coffee chains. Stay within FSA mercury limits (up to 4 medium tins or 2 fresh steaks/week).

Key recommendation: Per 100 g drained: ~ 25 g protein, ~ 240 mg K, ~ 200 mg P.

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

Plain tinned tuna in spring water (drained) is one of the most renal-friendly convenience proteins. Avoid tuna in brine, flavoured pouches and tuna mayonnaise sandwiches from coffee chains. Stay within FSA mercury limits (up to 4 medium tins or 2 fresh steaks/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 Tuna Good for Your Kidneys?

Spring water vs brine vs oil

Spring water (drained): lowest sodium, lowest fat — the renal-diet default. Oil (drained): adds 80–120 kcal; olive oil versions are heart-friendly but watch portion. Brine: typically 300–500 mg sodium per tin — avoid on a renal diet.

Mercury and CKD

FSA guidance: adults can have up to 4 medium tins or 2 fresh tuna steaks per week. Pregnant women: maximum 2 tins or 1 steak. CKD does not change mercury clearance dramatically, but staying within FSA limits is sensible — vary your fish with salmon, mackerel, sardines, cod and haddock.

Practical CKD-friendly ideas

  • Tuna and cucumber jacket potato (use leached potato).
  • Tuna pasta salad with sweetcorn, peppers and lemon — skip jarred dressings.
  • Niçoise-style salad with new potatoes, green beans, boiled egg, olive oil.
  • Avoid: shop-bought tuna mayo baguettes (often 1.5–2 g salt), tuna melts on white bread with cheese.
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

Plain tinned tuna in spring water (drained) is one of the most renal-friendly convenience proteins. Avoid tuna in brine, flavoured pouches and tuna mayonnaise sandwiches from coffee chains. Stay within FSA mercury limits (up to 4 medium tins or 2 fresh steaks/week).

Key takeaways
  • Per 100 g drained: ~ 25 g protein, ~ 240 mg K, ~ 200 mg P.
  • Choose 'spring water, no added salt'. Drain before eating.
  • Avoid tuna in brine — sodium can exceed 400 mg per tin.
  • FSA mercury cap: ≤ 4 medium tins or 2 fresh steaks per week.
  • Skip pre-made tuna mayo sandwiches (high salt + fat).
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 tinned tuna good for kidneys?

Tinned tuna in spring water is a renal-friendly lean protein. Choose 'in spring water, no added salt' and drain well. Avoid tuna in brine (high sodium) and flavoured pouches (mayonnaise, sweetcorn, sodium additives).

How much tuna can I eat with CKD?

The FSA advises adults can have up to 4 medium tins (or 2 fresh steaks) of tuna per week because of mercury. For CKD, this also fits typical protein targets — one 80–100 g drained tin counts as one protein portion.

Is tuna high in potassium or phosphate?

No — tuna is naturally moderate in both. A 100 g drained portion gives ~ 25 g protein, ~ 200 mg phosphate and ~ 240 mg potassium. The bigger risk is added sodium in brine or flavoured varieties.

Can I eat tuna on dialysis?

Yes — dialysis raises protein needs (1.0–1.2 g/kg/day) and plain tinned or fresh tuna is a convenient, kidney-friendly option. Watch sodium and avoid smoked or salt-cured tuna.

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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