How much sushi is too much sushi?

Fish overconsumption, biomagnification and the dangers of mercury poisoning

Sushi just so happens to be one of the most popular food dishes on campus ever since it has been introduced by Aramark Higher Education. Often, one can stroll into McKinley food court and find some of the student body eating from Bento or the pre-made, store-bought California rolls. A sushi roll usually consists of rice, a nori sheet, some chopped vegetables and fish.
“When I eat sushi, I’ll usually go for the California roll or spicy tuna,” Sarah Csonka, ’26, said. “And usually I eat one or two servings per week.”
No matter how delicious sushi is, there is a potential health risk involved with consumption, more so overconsumption of raw fish. Fish are not only filled with mercury, but a twice-as-toxic mercury called methylmercury. Usually, if the fish is smaller, it has less mercury, but predators of those smaller fish are far more problematic.
“There’s this concept called biomagnification,” said Associate Professor of Biology Lisa Whitenack. “Where the fish at the top of the food chain or food web — they accumulate all of the toxins of what they eat have picked up.”
Whitenack explained that it is important to analyze what part of the food chain a fish is, because that affects the amount of mercury. If it is a top predator, it will be filled with mercury. If it is at the bottom of the chain, it will have a lower amount.
This means that shrimp — which are not eaten raw in the first place — have very low mercury levels. On the contrary, fish like cape salmon, bigeye and bluefin tuna — often eaten raw when prepared as sushi — have incredibly high mercury levels. Both fish exhibit mercury levels around 0.6-0.8 parts per million, according to the Journal of Environmental Science and Health. This may seem low, but approaches the healthy limit of 1 ppm per week.
The World Health Organization considers mercury to be one of the top ten chemicals for “major public health concern.”
It can sometimes be hard to gauge mercury levels, though. Fish mercury levels are also affected by the environment.
“How was it raised?” Whitenack said. “Was it wild-caught? Was it farm-raised? That makes a difference, too.”
How the fish were raised can affect if parasites and neo-pathogens infiltrate our food, according to the Journal of Environmental Science and Health. Most fish, when raw, have bacteria that produce extended-spectrum beta-lactamases, which are enzymes that are naturally resistant to some antibiotics, usually found in the bowels. Like many bacteria humans have, as long as they remain there in small quantities are generally harmless. When there are too many within the human body, though, it can cause a life-threatening infection.
Whitenack offered resources on identifying not only what fish are safer for consumption, but also what fish are sustainable.
“The Monterey Bay Aquarium has this program named ‘Seafood Watch’ where you can actually go onto their website and print out a little card for your wallet that is specific to the region you live in — because that also makes a difference — and it tells you which seafoods are sustainable and healthy and which aren’t,” Whitenack said.
But how do you know if you have had too much sushi and are suffering from mercury poisoning? According to the Mayo Clinic, symptoms include tingling, numbness and poor muscle coordination — and it is hardly referring to general clumsiness or anxiety.
Mercury poisoning becomes consistent and requires extreme medical procedures thanks to potential threats to the central and peripheral nervous system; more specifically, the kidneys, lungs, immune system and digestive system.
Both Nicole Dann-Payne, Allegheny’s dietician, and Aramark Dining declined to comment.
“Doing research on the consumption of raw fish as a global health major, I can say that overconsumption of raw fish can lead to illness and that this shouldn’t be in everyone’s option list for a daily food item,” said Sha Lilley, ’24.
General sushi consumption on a weekly basis should be no more than 10 to 15 rolls, according to Health Magazine. This should especially be taken into consideration if the sushi ingredients include tuna, salmon or any raw fish.
“I try to limit sushi consumption to, like, every other week, but I know that you’re not supposed to have it more than, like, three times per week,” Lilley said.
As tasty and popular as it is, it is also not the healthiest option and should be taken lightly. There is a limit to the amount of sushi — more specifically, raw fish — that can be consumed before health risks develop.
“I know it’s not good to consume sushi frequently,” Lilley said. “I always try to get the tempera because I know it’s a cooked shrimp or cooked meat.”