Fish consumption may be linked to better heart health and a lower risk of obesity in adults, as well as improved cognitive function in children. A 2019 review of 106,237 mother-offspring pairs found an average 7.7 IQ point gain in children whose mothers ate seafood during pregnancy, compared to people who didn’t eat fish when pregnant. The U.S. Food and Drug Administration (FDA) also notes that along with providing high-quality protein, seafood contains omega-3 fats and minerals such as iodine, iron, selenium, and zinc. Seafood also offers more vitamin D and B12 than any other food.
What About Mercury?
In recommending seafood, the Dietary Guidelines Advisory Committee addressed the issue of methylmercury levels in some types of seafood. “In terms of neurocognitive development, fish is the primary dietary source of long-chain polyunsaturated omega-3 fatty acids, which are needed for brain development,” the report states. “Thus, the benefits of seafood need to be weighed again the potential for negative health consequences due to possible contamination with heavy metals, chiefly methylmercury.” Concerns about methylmercury (which is formed in fish and other seafood when mercury is present in their diet) may have steered some pregnant individuals away from fish completely. However, not all types of seafood present an equal risk. The FDA categorizes fish based on mercury levels and reports the following as the safest for people who are pregnant, may become pregnant, or are breastfeeding: That said, it’s important for people to be aware of the potentially harmful health effects of eating high-mercury fish on a regular basis, according to dietitian Julie Cunningham, RD, LDN. “Mercury can accumulate in the body and become toxic to the brain and nervous system over time,” she says.
Omega-3s and Vitamin D
Incorporating more low-mercury seafood choices into a regular rotation is important for increasing omega-3 fatty acids, according to certified nutritionist Aimee Aristotelous, CN, who specializes in prenatal nutrition.
King mackerelMarlinOrange roughySharkSwordfishTilefish (Gulf of Mexico)Bigeye tuna
There are three important types of omega-3 fatty acids and they come from two primary dietary sources:
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are mostly found in fatty seafood such as salmon, tuna, anchovies, mussels, and oysters. Alpha-linolenic acid (ALA) comes from vegetable oils (such as canola), nuts, flaxseeds and flaxseed oil, and leafy vegetables.
The vital health benefits attributed to omega-3 fatty acids come from EPA and DHA, says Aristotelous. “Seafood, by leaps and bounds, is the best dietary source of DHA and is really the only food which will give adequate amounts of the fatty acid,” she notes. “The body converts ALA into EPA, but in very little amounts; the conversion is usually less than 5 percent.” Another health boost, she adds, is that choices like salmon, sardines, and tuna are the best dietary sources of vitamin D. Research suggests that pregnant people who get higher amounts of this vitamin reduce the chances of complications from preterm birth, gestational diabetes, and infection. “Between the fatty acids and vitamin D found in fish, it truly is a superfood which should be taken seriously during pregnancy,” Aristotelous says.
