There are many different types of sushi, which are made with a wide variety of ingredients, including different types of vegetables, sea vegetables, and seafood. The basic ingredient for all sushi is rice; therefore, the other ingredients you choose to have on your sushi will determine its comparative nutritional value.
Varieties of sushi that include only rice and vegetables offer nutrient-rich vegetarian options for sushi. For example, many restaurants offer sushi made with shiitake mushrooms, avocado, cucumber, burdock, umeboshi plum paste (a pickled plum suggested to have stomach health-promoting properties), and natto (a fermented soybean food that contains isoflavones and has been found to help promote bone health).
Other varieties of sushi are wrapped in nori, a type of sea vegetable. Sea vegetables are rich in nutrients, including minerals (such as iodine) and phytonutrient lignans.
Before we talk about the raw fish issue, it's worth adding in a distinction about the terms "sushi" and "sashimi." In Japanese, the word "sushi" refers to seasoned rice, not to fish at all. As I mentioned earlier, sushi may or may not contain fish. If it contains fish, the fish might or might not be raw. If the fish isn't raw, it may actually have been cooked. More likely, however, the non-raw fish in sushi will have been marinated in a liquid that includes an acidic ingredient like vinegar or lime juice. The term "sashimi" refers directly to sliced raw fish, often served with soy sauce and wasabi (green horseradish).
When eating sashimi, or sushi topped with raw fish, a good approach is to enjoy it at a responsible restaurant, which has high quality purchasing and preparation practices. This is important so that you can reduce your risk of eating contaminated raw fish (which obviously is not healthy). Some of the health hazards connected with raw fish involve parasitic worms like tapeworm, flatworm, or roundworm. Roundworm (Anisakis simplex) may be the most problematic of the three parasites. If fish has been commercially frozen for at least three days at a temperature of 4°F (-16°C), all of these worms—and their larvae—will be killed, rendering the fish more safe. (Your freezer at home most likely cannot reach a temperature this low.) It's also good to eat it with some wasabi, which has traditionally been revered for its antimicrobial properties.
There are many types of fish that you can find in a sushi restaurant that contain great concentrations of nutrients. Omega-3-rich fish such as salmon, tuna, and mackerel are popular sushi options (don't forget that yellowfin or ahi tuna contains less mercury than albacore tuna). Pregnant woman and people with compromised immune systems may not want to take the risk of eating raw fish sushi at all and should discuss this with their healthcare provider.
While all types of sushi can be healthy, you will receive more vitamins from sushi made with vegetables, more minerals from sushi that is wrapped in seaweed, and more protein (and omega-3s, depending on the type of fish) from sushi topped with fish.
Ikeda Y, Iki M, Morita A, et al. Intake of Fermented Soybeans, Natto, Is Associated With Reduced Bone Loss in Postmenopausal Women: Japanese Population-Based Osteoporosis (JPOS) Study. J Nutr. 2006;136(5): 1323-8.
Katsuyama H, Ideguchi S, Fukunaga M, et al. Promotion of Bone Formation by Fermented Soybean (Natto) Intake in Premenopausal Women. J Nutr Sci Vitaminol (Tokyo). 2004;50(2): 114-20
Katsuyama H, Ideguchi S, Fukunaga,M, et al.Usual Dietary Intake of Fermented Soybeans (Natto) Is Associated With Bone Mineral Density in Premenopausal Women." J Nutr Sci Vitaminol (Tokyo) . 2002;48(3): 207-15.
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