Fish

Studies in people

• Concern

  Oily rectal leakage³

  Eating certain fish like escolar and oilfish can cause oily orange leakage from the rectum, plus nausea and cramps.

• Open question

  Heart attack risk⁷

  Eating nonfried fish may lower heart attack risk, but fried fish may raise it.

• Benefit

  Memory and thinking in later life⁸

  People who ate the most fish were less likely to develop memory problems and dementia.

• Open question

  Contaminated seafood outbreaks¹¹

  In the US, contaminated fish caused 857 outbreaks, with tuna, mahi-mahi and grouper most often to blame.

Found in some samples or products

These come from where it was grown, how it was processed or cooked, or what it was made into. They are not about the ingredient itself, so the signal does not count them.

• Mercury in young children⁴

  Young children who ate fish, especially tuna, had more mercury in their toenails than children who ate none.

• Foodborne illness from seafood⁶

  Eating bacterially contaminated fish can cause histamine poisoning, and cooking does not destroy the histamine.

• Mercury in seafood⁹

  Older people who eat more fish had the highest mercury levels in their hair.

• Contaminant awareness gaps¹⁰

  Many people did not know dried fish can hold pesticides, tiny plastics and heavy metals.

• Fetal brain development¹²

  In pregnant women, eating more fish may expose the baby's developing brain to methylmercury, which could affect development.

• Chemical build-up in the body¹⁴

  People who ate a lot of Baltic fish had the most of 10 fluorochemicals in their blood.

• Mercury in seafood¹⁵

  Fish and seafood can carry mercury, and teens and older people who eat a lot may take in more than is recommended.

• Contaminated wetland food¹⁶

  Fish and water from Ndop wetlands may carry pesticides like chlorpyrifos, which could pose a health risk.

• Heavy metals in seafood¹⁷

  Some fish from the Persian Gulf had high levels of nickel and lead, which scientists say may be a health concern.

Allergies and intolerances

These are about people with an allergy, an intolerance or coeliac disease. The signal is about the ingredient itself, and these are about the person eating it, so the signal does not count them.

• Food allergy in adults⁵

  Fish and shellfish are a leading cause of food allergy in American adults, with shellfish the top trigger.

How it’s made and used

• Contaminants in seafood¹³

  In people in Northern Italy, fish was the main source of arsenic and mercury, but average weekly intake stayed below safety limits.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.