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Nutrition and daily life

Fish and seafood — food card: benefits and safety

Caspian kutum, sturgeon, salmon — fish has a special place on our table. It gives easily digested protein, omega-3 fats and vitamin D. This card brings together why fish is useful and how to choose and cook it safely during treatment.

Last updated: ~2 min read
Well-cooked fish and seafood are a valuable protein source during treatment
Figure 1.Well-cooked fish and seafood are a valuable protein source during treatment.

01Short answer

Fish is a source of easily digested complete protein, omega-3 fatty acids, vitamin D, iodine and selenium. During treatment, well-cooked fish is a soft food that is gentle on the mouth. The key rule: cook fish through (63 °C, flesh opaque and flaking easily). During neutropenia, sushi, raw oysters, cold-smoked and lightly salted raw fish are usually not recommended. Cook fresh fish within 1–2 days or freeze it.

02Simple explanation

Fish provides complete protein and is softer than meat, so it is easier to eat with mouth sores.

Oily fish (salmon, mackerel, herring) is rich in omega-3 and vitamin D.

Raw fish can carry bacteria and parasites, which is dangerous with weak immunity.

Cooked fish turns white and opaque and separates easily with a fork.

03Scientific explanation

Temperature: FoodSafety.gov advises cooking fish to 63 °C (145 °F) inside; leftovers are reheated to 74 °C.

Weakened immunity: CDC advises avoiding raw and undercooked fish, cold-smoked fish and raw shellfish.

Mercury: the FDA advises limiting large predatory fish (shark, swordfish) and choosing lower-mercury fish (salmon, sardines, cod).

04What happens in the body?

What does fish provide?

Protein (about 20–25 g per 100 g cooked fish), omega-3, vitamin D, B12, iodine and selenium. White fish is lean; oily fish has more energy.

Three glowing spheres rise from a piece of cooked salmon towards outlines of a heart and a brain.
Figure 2.Oily fish provides omega-3, protein and vitamin D.

How to choose

Fresh fish has bright eyes, red gills, firm flesh and a mild sea smell, not a sharp one. Buy fish kept chilled or on ice.

How to cook

Bake, stew, steam or poach. Cook until opaque and flaking easily.

A fork separates the flakes of baked white fish, a slim thermometer beside it.
Figure 3.Cooked fish is opaque and flakes easily.

Seafood

Prawns, mussels and squid must be fully cooked: prawns turn pink-white, mussels open. Throw away mussels that stay closed.

What to set aside

Sushi, sashimi, raw oysters, lightly salted herring and cold-smoked salmon are usually off the menu during neutropenia. Hot-smoked fish is safer once reheated.

05Fish: four steps

Choose fresh, skip raw, cook fully, store well.

Choose fresh — Bright eyes, red gills.1Choose freshBright eyes, red gills.
No raw fish — Baked fish instead of sushi.2No raw fishBaked fish instead of sushi.
Cook fully — 63 °C, opaque.3Cook fully63 °C, opaque.
Cool and store — Within 2 hours, 1–2 days.4Cool and storeWithin 2 hours, 1–2 days.
Soft proteinGentle on the mouth.
Omega-3For heart and vessels.
Less riskProper cooking.

06Fish dishes during neutropenia

FoodRiskierSafer
SalmonSushi, cold-smokedOven-baked
HerringLightly salted rawFried, poached
PrawnsRaw, undercookedFully boiled
CaviarRaw roeAsk your doctor
Kutum, sturgeonUnderdone kebabFully cooked, flaking

* The table is general information; follow your team.

07Key terms

Omega-3
Beneficial fatty acids found in fish.
Opaque
The white, matt look of cooked fish.
Cold smoking
Treating fish with smoke without heat.
Mercury
A metal that builds up in large fish.
Shellfish
Mussels, oysters, prawns and similar.
Internal temperature
The heat in the thickest part of the fish.

08Key points

  • Fish is soft, complete protein.
  • Oily fish gives omega-3.
  • Cook fish to 63 °C.
  • No sushi during neutropenia.
  • Discard mussels that stay closed.
  • Cool leftovers quickly.

09Frequently asked questions

Is canned fish OK?

Yes, a can that is not bulging and within date is usually safe. After opening, keep it in the fridge and eat within 1–2 days.

Should I take fish oil capsules?

Supplements can affect blood clotting and medicines. Take them only if your doctor agrees.

Can I eat caviar?

Caviar is raw. It is usually not recommended during neutropenia; ask your doctor.

How often should I eat fish?

The NHS suggests at least 2 portions a week, one of them oily. A dietitian can tell you what suits you.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Is canned fish OK?

  2. Should I take fish oil capsules?

  3. Can I eat caviar?

  4. How often should I eat fish?

My questions

12Sources

  1. NHS. Fish and shellfish
  2. FoodSafety.gov (U.S. HHS). Cook to a Safe Minimum Internal Temperature
  3. CDC. Safer Food Choices for People With Weakened Immune Systems
  4. U.S. FDA. Advice about Eating Fish
  5. Leukemia & Lymphoma Society. Diet Guidelines for Immunosuppressed Patients
  6. Memorial Sloan Kettering Cancer Center. Food Safety During Cancer Treatment
  7. Clinical Nutrition (ESPEN), 2021. Muscaritoli M et al. ESPEN practical guideline: Clinical Nutrition in cancer
  8. National Cancer Institute (NCI). Complementary and Alternative Medicine (CAM)
  9. National Cancer Institute (NCI). Oral Complications of Chemotherapy and Head/Neck Radiation (PDQ®) – Patient Version
  10. National Cancer Institute (NCI). Nutrition in Cancer Care (PDQ®) – Patient Version
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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