May have parasites

Even though tuna is highly nutritious, eating it raw may pose some risks.

This is because raw fish may contain parasites, such as Opisthorchiidae andAnisakadie, that can cause diseases in humans (6, 7Trusted Source).

Depending on the type, parasites in raw fish can lead to foodborne illnesses, marked by intestinal infections that trigger diarrhea, vomiting, fever, and related symptoms (8Trusted Source).

One study found that 64% of samples of young Pacific bluefin tuna from Japanese waters were infected with Kudoa hexapunctata, a parasite that leads to diarrhea in humans (9Trusted Source).

Another study noted similar results and showed that samples of both bluefin and yellowfin tuna from the Pacific Ocean contained other parasites from the Kudoafamily that are known to cause food poisoning (10Trusted Source).

Finally, a study in tuna from waters off the coast of Iran found that 89% of the samples were infected with parasites that can attach to the human stomach and intestines, causing anisakiasis — a disease marked by bloody stools, vomiting, and stomach pain(11Trusted Source, 12Trusted Source).

The risk of parasitic infection from tuna likely depends on where the fish is caught. What’s more, handling and preparation can determine whether parasites get passed along.

Most of the parasites can be killed by cooking or freezing (13Trusted Source).

Therefore, parasitic infections from raw tuna can be prevented through proper handling