In 2018, doctors pulled a 5-and-a-half-foot parasitic tapeworm out of a man's body that may have been caused by eating sushi. But was this case just a fluke, or can you actually endanger your health by frequently indulging in rainbow rolls?
Insider spoke with Dr. Tania Dempsey, a primary care physician and founder of Armonk Integrative Medicine in Armonk, New York, and Stella Metsovas, nutritionist and author of "Wild Mediterranean," about the scary things that can happen to your body when you consistently eat a lot of raw fish, from parasitic worm infections to listeria.
Read on to find out more about the risks.
Eating large amounts of big ocean fish, like tuna and yellowtail, can lead to mercury poisoning.
Mercury poisoning can lead to "memory problems, muscle weakness, numbness and tingling, tremors and irritability," according to Dr. Tania Dempsey.
"All fish contain some level of mercury, but most of the fish that is used in sushi rolls and sashimi are large fish, such as tuna, yellowtail, bluefin, sea bass and lobster, and they have the highest amounts of mercury," Dr. Dempsey said.
A parasitic tapeworm is probably one of the most nightmarish things you could ever find in your sushi.
In another case, a man who was complaining of abdominal pain after eating sushi went in for an X-ray. Doctors found the parasite suctioned to the mucus in his upper abdominal wall.
"The parasite that is on the rise is Anasakiasis, or herring worm disease," Dr. Dempsey said. "Anisakis attaches itself to the stomach or intestines and causes acute abdominal pain, vomiting, and fever. In some cases, it can lead to an allergic, anaphylactic reaction."
Listeria — a serious infection caused by contaminated food — is often found in both smoked and raw fish.
"Pathogenic bacterias like Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus can wreak havoc in your gut," nutritionist Stella Metsovas told Insider. "The major dangers of consuming raw fish can translate to infectious diseases that could result in severe abdominal pain, nausea, and vomiting."
Salmonella is another foodborne illness often found in raw fish and meat that's not properly prepared.
Eating sushi when it's fresh and cold is not just the best way to eat raw fish, but also the safest.
"Scombroid food poisoning is another food-borne illness caused by histamine that forms when fish are not kept cold enough and start to decay," Dr. Dempsey said. "The excess histamine does not get destroyed during heating and can cause allergic reactions and even anaphylaxis."
A 2008 report notes that scombroid poisoning accounted for 38 percent of all seafood-related food poisoning outbreaks in the United States, according to Food Safety Watch.
You could also expose yourself to man-made toxins.
Farm-raised salmon on ice.
Lemer Vadim/ Shutterstock
There is a debate within the seafood community if farm-raised or wild caught fish is better or healthier for you. While farm-raised fish will not carry a risk of parasitic worms, they will be exposed to man-made toxins.
"Toxin exposure from sushi is significant," Dr. Dempsey said. "PCBs [chlorine compounds] and pesticides have been found to contaminate farm-raised fish as well as wild fish from the Pacific Ocean and Indian Ocean. Ciguatoxins are toxins produced by marine algae microorganisms that affect fish that feed near reefs such as red snapper, grouper, jack and barracuda."
Ingestion of ciguatoxins in large quantities can cause nausea, vomiting, diarrhea, followed by neurological symptoms, and in rare cases, hallucinations or anxiety.
Choose smaller fish when you order sushi so your risk of consuming contaminants is lower. Dr. Dempsey also recommends asking the sushi restaurant where they source their seafood. She advises avoiding fish that has been farm-raised or caught near reefs.
