The benefit of a diet rich in omega-3 fatty acids in helping to reduce the risk of heart disease has received a lot of media attention lately. Omega-3 fatty acids are also very important for pregnant and breastfeeding women. One omega-3 fatty acid in particular – docosahexaenoic acid, or DHA – is considered essential for the optimal development of an infant’s brain and eyes, both during pregnancy and after birth. In addition, DHA may help prevent preterm labor and may help protect against postpartum depression.
During pregnancy, the fetus receives DHA from its mother through the placenta. Transfer of DHA from the mother to the fetus is greatest during the third trimester, a period of rapid development for the brain and nervous system. After birth, breast-fed infants continue to receive DHA through their mother’s milk.
The potential benefits of a diet rich in DHA during pregnancy and while breastfeeding have been under investigation for many years. Studies comparing infants born prematurely with full-term infants have found that preterm infants tend to have lower DHA levels as well as delayed visual and cognitive development. Other studies looking at breast-fed babies versus formula-fed babies (most formulas do not contain DHA) have found that breast-fed infants tend to have better visual acuity early in life.
Pregnant and breast-feeding mothers are encouraged to pay special attention to their diets to ensure an adequate consumption of foods rich in DHA. Currently, there is no dietary recommendation in the United States for the amount of DHA that should be consumed daily. However, the International Society for the Study of Fatty Acids and Lipids recommends pregnant women consume at least 300 milligrams of DHA each day.
Cold-water fish, such as salmon, herring, mackerel and whitefish, are our best dietary sources of DHA. Indiscriminate consumption of fish, however, is not recommended for pregnant women. This is because many of our streams and oceans are contaminated with methylmercury, which can be harmful to a developing nervous system. While nearly all fish contain trace amounts of methylmercury, long-lived, larger fish that feed on other fish accumulate the highest levels and pose the greatest risk to people who eat them regularly. For these reasons, the Food and Drug Administration recommends that pregnant women or those thinking of becoming pregnant avoid shark, swordfish, king mackerel and tilefish. The FDA has determined that up to 12 ounces per week (3 ounces is a normal serving size) of other cooked fish is safe for pregnant and nursing women. A good substitute for women who chose not to eat fish are the DHA-enriched eggs now available in many markets. Other functional foods containing omega-3 DHA should be on the market soon.
For the infant, breast milk is an excellent source of essential fatty acids, including DHA and AA, or arachidonic acid. While infant formulas supplemented with DHA and AA have been available for several years in countries throughout Europe, Asia, Africa, Australia and Latin America, they have not been allowed in infant formulas sold in the United States until recently. Currently, there are two brands of infant formula on the market in the United States that are supplemented with DHA and AA. These cost 10 percent to 20 percent more than regular formulas and have not been endorsed by the American Academy of Pediatrics due to lack of conclusive evidence supporting the benefits of supplementing infant formulas with the two fatty acids.