Alan Frischer, MD, MPH
Updated: Sep 26, 2021
Growing up here in Southern California, sushi was not a “thing.” It was difficult to find and my parents had no interest. That has changed, and today my own (adult) children and I love sushi. Is raw fish a healthful food to eat, or are we putting ourselves at risk by consuming it? Are we actually eating what we think we are?
Let’s start with the good news. Sushi is a simply prepared fish, a good source of protein, and is low in fat and calories. Most sushi contains omega 3 fatty acids, which have been shown to lower cholesterol and to improve symptoms of depression, along with a number of other benefits. (However, white rice is a simple carbohydrate and not as nutritious as brown rice.) Let’s take a (not very Japanese) California roll. Six pieces have about 250 calories and seven grams of fat, and contain crabmeat, avocado, cucumber, sticky rice flavored with vinegar, seaweed, ginger and soy sauce. In contrast, a fast food burger with cheese will likely have about 750 calories, and that’s before the soda and fries.
However, certain fish contain high levels of mercury. According to the FDA and the EPA, most women of childbearing age, along with children, should avoid high mercury levels. In fact, they advise women of childbearing age to eat no more than 12 ounces of fish per week. For the rest of us, fish is recommended twice a week. Frequent fish eaters (24 ounces or more per week), children, and woman of childbearing age should avoid the following high mercury fish: swordfish, shark, king mackerel, gulf tilefish, marlin, and orange roughy. Everyone should limit their consumption of these even higher-mercury fish: grouper, Chilean sea bass, bluefish, halibut, black cod, Spanish mackerel, and fresh tuna.
I’ve always been a fan of tuna salad sandwiches. Note that there are different kinds of tuna. Light tuna accounts for about 70% of the canned tuna we consume. The FDA considers canned light tuna a lower mercury fish that can safely be eaten twice a week, but other kinds of tuna may have triple the mercury, more calories, higher fat, and fewer omega-3 fatty acids. Because mercury levels even in canned light tuna may be inconsistent, the FDA recommends that pregnant women and young children avoid canned tuna altogether.
What about the risk of infection from eating raw fish? It is possible for raw fish to expose us to bacterial foodborne illnesses (think Hepatitis A and the Norwalk virus), which lead to diarrhea, cramping and vomiting. In addition, some parasites can be passed on in raw fish, although they are killed if the fish is frozen before consumption.
Do we really know what we are eating when we dine on sushi? Seafood fraud has garnered the interest of researchers since 2008, when two high school students performed DNA analyses and found that a quarter of fish products at Manhattan sushi restaurants and seafood markets were mislabeled. Other studies supported and even exceeded their findings of mislabeled fish, and mislabeling appears to continue.
As consumers, what should we do?
If you are dining out, be picky about where you eat sushi. Make sure that the restaurant is reputable and clean.
Government agencies do recommend eating fish (either raw or cooked) as a good source of low-fat protein, but also to limit total consumption and to be watchful of mercury levels, especially among children and pregnant women.
My bottom line: eat fish. It is very good for us. Mix it up, have different types, and keep portions small and mostly cooked. Sushi is a wonderful food - but not for daily consumption.