Ceviche is a popular seafood dish made by marinating raw fish or shellfish in citrus juices, such as lime or lemon. The acidity of the juice causes the proteins in the seafood to denature, which changes the texture and makes the flesh appear opaque, similar to when it is cooked with heat. However, for a pregnant person, this traditional preparation method is generally not considered safe due to the risks associated with consuming raw or undercooked seafood. Pregnant individuals have a naturally suppressed immune system, which makes them more susceptible to foodborne illnesses that can seriously affect both the mother and the developing baby.
Why Traditional Ceviche Is Risky
The primary risk in traditional ceviche lies in the preparation method itself, which relies on a chemical process instead of thermal cooking. The citrus juice, while acidic, only denatures the proteins in the fish, giving it a cooked appearance and firm texture. This process is not a reliable substitute for the high temperatures required to fully sterilize food.
Heat cooking to an internal temperature of 145°F is the standard for killing bacteria and parasites in seafood. The acid in the marinade, however, does not consistently kill all harmful microorganisms, including bacteria, viruses, and parasites that may be present in raw fish. Research shows that while some bacteria may be reduced, others, like Listeria monocytogenes, can remain highly viable even after being exposed to the ceviche preparation process.
Understanding Specific Pathogen Concerns
The consumption of raw seafood exposes a pregnant person to several specific foodborne pathogens that pose a high risk during gestation. One of the most significant threats is the bacterium Listeria monocytogenes, which causes an infection called listeriosis. Pregnant people are approximately ten times more likely to contract listeriosis than the general population.
Listeriosis can be particularly severe, even if the mother experiences only mild, flu-like symptoms. The infection can cross the placenta, leading to adverse outcomes for the fetus such as miscarriage, stillbirth, preterm labor, or severe blood and brain infections in the newborn. Other pathogens in raw seafood, including certain viruses like Norovirus and bacteria like Salmonella, also present risks for food poisoning, which can cause dehydration and complications during pregnancy.
Fish Selection and Mercury Considerations
Beyond the preparation method, the type of fish used in ceviche introduces a separate concern related to mercury content. Fish that are higher on the food chain and long-lived tend to accumulate higher levels of methylmercury in their muscle tissue through a process called biomagnification. Methylmercury is a neurotoxin that can affect the developing nervous system and brain of a fetus.
Many traditional or popular ceviche recipes use fish that are considered high in mercury and should be avoided entirely during pregnancy. These species include shark, swordfish, king mackerel, and tilefish. Pregnant individuals are advised to avoid these high-mercury fish and limit total seafood consumption to 8 to 12 ounces per week of low-mercury options.
Safe Alternatives to Traditional Ceviche
It is possible to enjoy the vibrant flavors of ceviche by modifying the preparation to eliminate the risks associated with raw seafood. The safest method involves thoroughly cooking the fish or shellfish with heat before marinating it in the citrus juice and mixing in the other ingredients. Cooking the seafood to an internal temperature of 145°F ensures that any harmful bacteria or parasites are destroyed.
Low-mercury options like shrimp, scallops, tilapia, or cod are excellent choices for a pregnancy-safe ceviche alternative. You can boil or steam the seafood until it is fully cooked, then dice it and proceed with the traditional marinating and seasoning steps. This approach allows for the enjoyment of the characteristic tangy flavor and texture of ceviche while providing the omega-3 fatty acids and protein found in seafood without the raw-food risks.