The FDA requires that most fish used commercially for sushi be frozen (at -4°F for seven days, for example) to kill parasites. Well-trained sushi chefs know how to buy, examine, store, and handle fish to minimize the risk of illness and parasitic infection. While chefs are licensed in Japan, it’s hard to evaluate their experience in this country.
Most tuna species carry little risk of parasites, but the safest option is to eat sushi made with fully cooked fish, such as shrimp (“ebi,” not “ama ebi”), eel, and crab (both real and imitation). Pregnant women, young children, and people with compromised immunity or in frail health should avoid all uncooked seafood.
Buy take-out sushi only from reputable, clean establishments. Make sure it is fresh and refrigerated below 41°F— though that may be hard to tell. If the containers are stacked, choose cooler ones from the bottom. Like raw fish, cooked rice is susceptible to bacterial growth if it is not properly refrigerated.
Sushi can be a good source of healthful omega-3 fats, protein, and other nutrients. Sushi is generally low in calories, with only about 40 to 60 calories per piece of sashimi and about 300 to 400 calories per large eight-piece roll. But many Japanese restaurants in the U.S. serve Westernized portions and combination plates, in which calories can add up. And many sushi ingredients and condiments—such as seaweed, soy sauce, and pickled ginger—are also high in sodium.
Also see Catch the Health Benefits of Fish.