Consuming raw fish, such as in sushi or sashimi, while breastfeeding involves balancing the nutritional benefits of seafood against two distinct health concerns. These concerns relate to the immediate risk of foodborne illness from raw preparation and the long-term risk of chemical contaminant exposure, which is independent of cooking. Understanding the specific nature of each risk allows for informed choices regarding seafood consumption during the postpartum period.
Understanding Pathogen Risk in Raw Seafood
Raw seafood carries a risk of microbial contamination from bacteria and parasites that are eliminated by cooking. The primary danger is exposure to pathogens like Salmonella, Vibrio, and the parasite that causes anisakiasis. While these pathogens usually cause self-limiting gastrointestinal illness, a severe maternal infection can indirectly impact the infant’s care.
Listeria monocytogenes is a bacterium of particular concern because the resulting infection, listeriosis, can be severe in immunocompromised individuals. Although the risk of passing listeriosis to the infant through breast milk is low, severe maternal illness may disrupt the breastfeeding relationship. Cooking fish to 145°F (63°C) is the most effective way to kill these bacteria and parasites.
In contrast to bacteria, parasites are often killed by the freezing process used for commercially prepared sushi-grade fish. However, freezing does not eliminate bacterial contamination. Shellfish, such as raw oysters, carry a higher risk of bacterial and viral infections, including norovirus, compared to finfish.
Heavy Metals and Contaminants in Breast Milk
The second, long-term concern with fish consumption is the accumulation of environmental toxins, which cooking does not mitigate. Methylmercury is the most recognized contaminant, originating from inorganic mercury that is converted by microorganisms and bioaccumulated up the aquatic food chain. This heavy metal accumulates in the muscle tissue of the fish, so trimming the skin or fat does not reduce its concentration.
When a mother consumes methylmercury, a portion can pass to the infant through breast milk, although the transfer is less significant than the exposure that occurs during pregnancy via the placenta. Methylmercury is a known neurotoxin, and infant exposure is linked to adverse effects on the developing brain and nervous system. The concentration is highest in large, long-lived predatory fish because they accumulate the compound through their diet.
Beyond methylmercury, certain types of seafood, particularly fatty fish, can also contain persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs). PCBs are fat-soluble compounds that accumulate in a mother’s adipose tissue and can be excreted into breast milk. Consuming fish high in these compounds can still contribute to the infant’s exposure.
Safe Seafood Consumption Guidelines for Breastfeeding Mothers
Federal health agencies recommend that breastfeeding mothers consume fish for its nutritional benefits, including Omega-3 fatty acids like DHA and EPA, which are important for infant brain and eye development. The U.S. Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA) advise consuming 8 to 12 ounces (two to three servings) per week of fish from the “Best Choices” category. A single adult serving size is generally considered to be 4 ounces of fish, measured uncooked.
To minimize exposure to both pathogens and contaminants, the advice for raw fish is straightforward: avoid it entirely. This includes sushi, sashimi, ceviche, and raw oysters, due to the persistent risk of foodborne illness from bacteria. The primary focus should be on selecting cooked fish that are low in mercury.
Fish to Avoid (High Mercury)
Fish to avoid due to high mercury levels include:
- Shark
- Swordfish
- King mackerel
- Marlin
- Orange roughy
- Tilefish from the Gulf of Mexico
Best Choices (Low Mercury)
Best choices, which are low in mercury, include:
- Salmon
- Canned light tuna
- Shrimp
- Pollock
- Tilapia
- Cod
- Catfish
By choosing fish from the “Best Choices” list and ensuring all seafood is thoroughly cooked to 145°F (63°C), mothers can gain the nutritional advantages of fish while managing the two distinct sets of health risks.