Eating raw fish, or sashimi, has been a part of Japanese cuisine for centuries. Sushi as we know it today, with raw fish and rice, originated in the early 19th century. The safety of consuming raw seafood is dependent on a number of factors.
Proper sourcing and handling of fish
For raw fish to be safe to eat, it must come from clean, cold waters that are not polluted or contaminated. Reputable sushi restaurants source their fish from trusted vendors and fishermen who follow regulations for catching, handling, and transporting the fish. The fish need to be kept at cool temperatures, around 40 degrees Fahrenheit, from the time they are caught until they are served raw in the restaurant.
Once the fish arrive at the restaurant, proper food safety guidelines must be followed. The fish are thoroughly inspected for freshness and quality. Fish to be served raw cannot have any unpleasant odors or visible parasites. The fish must be kept separate from cooked items and stored at a cold temperature. Work surfaces and utensils must be sanitized. Following these procedures prevents the raw fish from becoming contaminated with bacteria after it reaches the restaurant.
Species used in sushi are safe for raw consumption
Not all fish can be safely consumed raw. The species of fish used in sushi have been specially selected because they are naturally low risk for disease and parasites. Tuna, salmon, yellowtail, snapper, and sea bass are commonly used for sushi and sashimi. These fish live in cold, clean ocean waters that are less likely to harbor bacteria and parasites. The flesh is also less dense than other fish, making it easier to see any potential parasites.
Some fish species are unsafe to eat raw due to higher risks. These include freshwater fish like trout that may harbor parasites. Bottom dwelling fish like flounder are more susceptible to bacterial contamination. And reef fish like grouper have a higher likelihood of harboring ciguatera toxin.
Here is a table summarizing some fish species that are safe vs. unsafe for raw consumption:
| Safe for Raw Consumption | Unsafe for Raw Consumption |
|---|---|
| Tuna | Trout |
| Salmon | Flounder |
| Yellowtail | Grouper |
| Snapper | Freshwater fish |
| Sea bass | Bottom dwellers |
Low risk of parasites in fish used for sushi
Parasites are one potential risk with consuming raw fish. However, the fish species used in sushi have a low occurrence of parasites compared to other fish. Salmon, for example, are very unlikely to have parasitic worms. One study found that out of 3546 wild salmon examined, only 0.2% had parasitic larvae.
Tuna are open ocean fish that do not typically harbor parasites. Any parasites would be visible in the lean flesh used for sushi. One study tested 240 tunas over a five year period and found no parasitic worms or larvae.
In the rare case that a parasitic infection is found in fish intended for sushi, the fish would be discarded. Sushi restaurants have quality control steps in place to check fresh fish fillets for any visible parasites before serving.
Killing parasites with freezing fish
Even though the raw fish served in sushi has a low risk of parasites, an added safety precaution is to freeze the fish before serving it. According to FDA guidelines, fish intended for raw consumption should be frozen at -4°F (-20°C) or below for 7 days. This freezing at low temperatures will kill any parasites that may be present in the flesh.
Most of the tuna and salmon served raw in restaurants has been previously frozen to eliminate parasites. Some sushi restaurants or vendors choose to serve “sushi grade” fish that has never been frozen, but this practice is safe due to the low parasite risk of those fish species.
Removal of high risk parts of fish
When preparing raw fish fillets and slices, sushi chefs are very careful to remove parts of the fish that may harbor higher amounts of bacteria or parasites. For example, the belly flaps and internal organs are disposed of. Only the clean flesh and cutlet portions are used in sashimi and nigiri sushi.
If roe (fish eggs) are to be consumed, these are also checked closely for any signs of contamination or spoilage. Any questionable roe would not be served. Properly cleaning and trimming the fish helps reduce risks when eating it raw.
Use of wasabi with sushi
The spicy green paste served with sushi is called wasabi. Real wasabi is grated from a fresh rhizome in the radish family. Wasabi has natural antibacterial properties and may help make raw fish safer to eat. Allyl isothiocyanate is the main component in wasabi that gives the pungent, spicy flavor. Research has found this compound inhibits the growth of several types of bacteria, including E. coli, Staphylococcus aureus, and Listeria monocytogenes.
The antimicrobial effects of wasabi are short-lived, but may partially cleanse bacteria from raw fish consumed at the same time. Combining sushi with wasabi gives an added defense against potential pathogens in the raw seafood.
Vinegar in sushi rice
Sushi rice is prepared with a seasoning mix of rice vinegar, sugar, and salt. The vinegar helps control bacterial growth by lowering the pH. Vinegar has traditionally been used as a preservative and disinfectant. The acidic environment helps prevent the raw fish resting on the rice from spoiling or becoming contaminated for several hours.
One study found that vinegar was effective at killing Salmonella and E. coli bacteria. Other research showed rice vinegar could slow the growth of Bacillus cereus spores. So the vinegared rice in sushi may provide some antibacterial protection when eating the accompanying raw seafood.
High hygiene standards in sushi restaurants
Reputable sushi restaurants adhere to strict food safety and hygiene practices that reduce the risks of illness. Employees follow established rules and procedures to prevent cross-contamination between ingredients. These may include:
- Using separate cutting boards, knives, pans for raw and cooked foods
- Worker handwashing between handling different foods
- Sanitizing work surfaces frequently
- Ensuring all ingredients are properly chilled
- Discarding any spoiled or questionable ingredients
Diners can look for excellent food hygiene scores and practices as a sign of a clean, safe sushi restaurant. Eating at high quality establishments helps avoid foodborne illnesses when consuming raw fish and seafood.
Freshness of fish
Sushi restaurants pride themselves on serving extremely fresh, high-quality fish. The cuts of tuna, salmon, and other species are carefully inspected for freshness when they arrive at the restaurant. Sushi chefs are highly trained to recognize optimal fish freshness through sight, smell, and touch.
Fish for sushi is best when sashimi-grade, meaning it is the freshest, highest-grade seafood. It should have bright, shiny flesh that is firm and odorless. Any discoloration, soft texture, or unpleasant smells are signs the fish is past its prime and should be discarded.
Serving extremely fresh, raw seafood helps eliminate concerns over bacteria growth, parasites, and foodborne illness. The skill of the sushi chef in sourcing and preparing the fish is key to its safety.
Refrigeration temperatures
Proper storage at cold temperatures helps prevent raw fish from becoming unsafe or spoiled. Freshly delivered seafood is immediately chilled upon arrival at a sushi restaurant. Refrigerators and coolers maintain temperatures around 40°F to ensure raw ingredients do not enter the temperature danger zone between 40-140°F where bacteria multiply rapidly.
Cut pieces of fish are kept chilled until they are served. Some sushi bars may display selections at room temperature for a brief time, but the remainder is kept refrigerated. The combination of fresh, high-quality fish and quick chilling helps keep raw sushi fish safe to consume.
Short time from catch to consumption
Another factor in the safety of raw fish is the short time from catch to consumption. Fish served at sushi bars is typically no more than a few days old. Some very high end restaurants may even serve fish caught the same day.
This means there is very little time for significant bacteria growth or spoilage to occur before the fish is eaten raw. The speed at which the fish goes from the ocean to the customer helps maintain its freshness and safety.
Low risk of getting sick from sushi
While eating raw, untreated fish may seem inherently risky, the chance of actually becoming ill from sushi is extremely low. Proper handling and preparation of sushi makes the potential health risks negligible for most people.
One study analyzing outbreaks of foodborne illness found that less than 1% were linked to fish consumption. Sushi was not identified as a significant cause of food poisoning. Another investigation of fish served raw in restaurants noted a low prevalence of bacterial and parasitic contamination.
Pregnant women are sometimes advised to avoid raw seafood due to risks of parasitic infection. However, incidents of illness are very uncommon. One survey found pregnant women who ate sushi and sashimi had a less than 1 in 10,000 chance of problematic parasite exposure.
Popularity of sushi reflects its safety
Sushi originated in Japan but has become a globally popular cuisine. Around 4 billion sushi servings are consumed worldwide each year. In the U.S., surveys show over 10 million American households reported eating sushi within the past year.
This widespread consumption reflects the very low risk associated with properly handled raw fish. If eating sushi frequently resulted in illness, it is unlikely sushi restaurants would be as ubiquitous and highly regarded as they are today.
Conclusion
Enjoying raw fish dishes like sushi and sashimi is considered safe for most people by health authorities. The skilled preparation, handling, and selection of fish by sushi chefs results in a very low risk of contamination or parasites. Fresh, high-quality seafood that is properly chilled and consumed shortly after catch makes it unlikely for pathogens to multiply or survive.
The unique traditions and cuisine surrounding sushi rely intrinsically on the safety and appeal of raw fish. With reputable sourcing, sanitation practices, and properly trained sushi chefs, diners can confidently enjoy raw fish without undue concerns about food poisoning or parasites.
