Medical science deems Omega-3 fatty acids absolutely essential for human health and for proper development of brain, eye, and nervous tissue in the fetus and growing infant. But the human body cannot make Omega-3's, so expectant and nursing mothers must obtain them from foods.
Most infant formulas sold in the U.S. contain fatty acids that babies can convert into DHA—the type of Omega-3 fatty acid proven most essential to brain and nervous system development. But it is uncertain whether infants can produce enough DHA in this way to meet their needs.
Among all human foods, only certain cold-water fish are rich in DHA. Omega-3s are also found in some plant foods (e.g., flax oil, hemp oil, nuts, and seeds), but they are of a type (i.e., linolenic acid) the body cannot easily convert to DHA.
However, some fish species high in Omega-3s are also prone to contain chemical toxins such as mercury, PCBs, and pesticides, which damage an infant's developing brain and nervous system. These contaminants accumulate in the fatty tissues of certain fish, and in the bodies of people who eat them.
The Fish to Favor
Which fish are both highly beneficial and very safe to eat during pregnancy and lactation? The healthiest species—those high in Omega-3s and low in contaminants—include Salmon (except from the Great Lakes), Farmed Trout, Sardines, Herring, and Pilchard. Among 11 species tested, the U.S. Food and Drug Administration reports that Tilapia and Salmon contain the lowest levels of mercury.
Many other commercial species are low in contaminants, but are also fairly low in Omega-3s. These include Flounder, Sole, Farmed Catfish, Striped Bass, Tilapia, Cod, Haddock, Mahi mahi (dolphin fish), Perch, Crab, Shrimp, Scallops, Clams, Oysters, Mussels, and Crayfish.
Fish to Avoid
Fish that eat other fish or live many years accumulate the most toxins. Several kinds of freshwater sport fish are frequently contaminated, too. Accordingly, pregnant and nursing women should avoid the following: Raw Fish, Raw Shellfish, Swordfish, Shark, King Mackerel, Fresh Tuna (sashimi and steaks), Tilefish (golden bass/snapper), Marlin, Bluefish, Bass (large and small mouth), Northern Pike, Walleye, Pickerel, Lake Whitefish, Great Lakes Salmon, Bowfin, Gar, Pufferfish (fugu), Blowfish, Sea Squab, and all fish subject to an official fish consumption advisory.
The FDA advises pregnant women and all women of childbearing age to avoid eating any shark, swordfish, king mackerel or tilefish, because of their high mercury content.
What About Tuna?
Probably the most controversial fish is tuna. The U.S. FDA has warned against eating more than 12 ounces of tuna per week. Canned tuna tends to have lower contaminant levels than fresh and frozen forms, in part because different tuna species are used. Although data are limited, tuna species sold fresh for sashimi and steaks generally come from larger older fish that are more likely to have higher contaminant levels. Vital Choice sells only the smallest surface or "troll-caught" albacore tuna, which are the youngest, purest fish.
Other Safety Tips
Infants and pregnant or nursing women should avoid all raw fish and shellfish, which can carry dangerous parasites and microorganisms, and all potentially toxic fish (e.g., pufferfish/fugu, blowfish, sea squab). Parents with seafood allergies or other serious allergies such as bee stings and pollen should not feed shrimp, crab, crayfish, and lobster to their children under the age of three, who may be prone to develop these allergies.
Editor's Note: This article includes information and excerpts from "Straight Talk About Eating Fish During Pregnancy," by Joyce A. Nettleton DSc, RD, which is posted on the Web site of the Alaska Seafood Marketing Institute (http://www.alaskaseafood.org/flavor/omega_article2.htm). We wish to thank Dr. Nettleton for her kind assistance and generosity.
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