Just as they need dietary vitamins, human beings require two kinds of essential fatty acids (EFAs)—omega-3s and omega-6s—to thrive and survive. This is why infant formula has long been fortified with the plant-derived omega-3 EFA known as ALA and the plant-derived omega-6 known as LA.
However, the human body cannot use ALA or LA, and must convert them into the “ready-to-use” omega-3 known as DHA (docosahexaenoic acid) and the “ready-to-use” omega-6 known as ARA (arachidonic acid). Among other reasons, human breast milk is considered superior to standard ALA/LA-fortified formula because it already contains DHA and AA.
In recent years, scientists have tried to discover whether it would be better to fortify infant formulas with the “ready-to-use” omega-3 DHA and omega-6 AA instead of ALA and LA, and have run experiments testing the effects of DHA/AA-fortified formulas on infants’ mental and motor development.
The results of these clinical trials have varied, but most have shown that feeding infants DHA/AA-fortified formulas yields significant developmental advantages, compared with the effects of standard ALA/LA-fortified formulas. Consequently, major manufacturers have begun offering formulas fortified with “ready-to-use” DHA and AA, instead of or in addition to ALA and LA.
Mothers’ milk with more DHA seen to enhance attention span
The latest study tested the effects of varying maternal DHA consumption (and resulting DHA blood levels) on infants’ cognitive development as determined by a scientific measure of attention span called “infant look duration.” Two sets of mothers were given differing amounts of DHA, attained by eating either standard eggs low in DHA, or DHA-rich eggs (from chickens fed DHA-rich fish meal).
The results showed that the infants of mothers who ate the DHA-rich eggs enjoyed small but significant advantages in attention span.
Almost all studies that have compared DHA/AA-fortified formulas to ALA/LA-fortified formulas either show benefit from formulas with DHA/AA or no effects. These results show that DHA/AA-fortification is both safe and beneficial, and that its benefits may not always be detectable by current methods.
While AA is also a key component of cell membranes, it is added mostly to ensure that the supplemental DHA in an infant formula does not produce any fatty acid imbalance that might affect growth. Ensuring adequate DHA is the primary goal of DHA/AA fortification, since it is so essential to brain and eye function. (DHA constitutes 12-15 percent of fatty acids in gray matter of the cortex and brain stem, and 25 percent of retinal fatty acids.)
Today, most research is focused on determining the exact amounts of omega-3 DHA and omega-6 AA that should be in formulas, which has been based in part on the amount of DHA found in average breast milk. However, modern diets are badly imbalanced in favor of the omega-6 LA, which predominates in vegetable oils and processed foods.
In fact, researchers suspect that the amount of DHA found in modern breast milk is probably much lower than it was during the vast majority of human history, when our bodies evolved in response to diets high in nuts, seeds, wild greens, fish, and game, all of which are naturally high in omega-3 EFAs (ALA or DHA).
Safest sources of dietary DHA
Health experts urge expecting mothers to eat plenty of foods high in omega-3s. It only makes sense to choose the only whole foods high in the “ready-to-use” omega-3 DHA: cold-water fish like salmon, mackerel, herring, and tuna.
Eggs high in DHA are a secondary choice, for two reasons. First, as Dr. Joseph Mercola notes, “… when DHA is given, it should be balanced with its cousin omega-3 fatty acid, EPA … if it is given out of balance, without EPA … it is potentially problematic”. Second, while “high-DHA” eggs contain about eight times as much DHA as a normal egg, you’d have to eat four of them to get as much DHA as a three-ounce serving of salmon. That’s a lot, especially for people watching their calorie or cholesterol intake.
Of course, expectant mothers must also be wary of contaminants, which occur at relatively high levels in farmed salmon (PCBs, dioxin, pesticides) and standard tuna (mercury). It only makes sense to choose the safest food sources of DHA: wild Alaskan salmon and young, low-weight wild Alaskan tuna.
Maternal DHA and infant-toddler attention span
· Colombo J, Kannass KN, Shaddy DJ, Kundurthi S, Maikranz JM, Anderson CJ, Blaga OM, Carlson SE. Maternal DHA and the development of attention in infancy and toddlerhood. Child Dev 2004;75:1254-1267.
DHA in neonatal and infant nutrition
· Benolken RM, Anderson RE, Wheeler TG. 1973. Membrane fatty acids associated with the electrical response in visual excitation. Science 182:1253-1254
· Carlson SE, et al. 1993a. Visual acuity development in healthy preterm infants: effect of marine-oil supplementation. Am. J. Clin. Nutr. 58:35-42.
· Carlson SE, et al. 1993b. Arachidonic acid status correlates with first year growth in preterm infants. Proc Natl Acad Sci 90:1073-1077.
· Champoux M, et al. 2002. Fatty acid formula supplementation and neuromotor development in rhesus monkey neonates. Pediatr Res 51:273-281.
· Cheruku SR, et al. 2002. Higher maternal plasma docosahexaenoic acid during pregnancy is associated with more mature neonatal sleep-state patterning. Am J Clin Nutr 76:608-613.
· Cunnane SC, et al. 2000. Breast-fed infants achieve a higher rate of brain and whole body docosahexaenoate accumulation than formula-fed infants not consuming dietary docosahexaenoate. Lipids 35:105-111.
· Mercola J. http://www.mercola.com/2003/jun/18/baby_formula.htm
· Uauy R, et al. 1992. Visual and brain-function measurements in studies of n-3 fatty-acid requirements of infants. J Pediat 120:S168-S180.
· Uauy R, et al. 2000. Long chain polyunsaturated fatty acid formation in neonates: effect of gestational age and intrauterine growth. Pediatr Res 47:127-135.