Dr. Greene’s Answer:
Breast milk is the best and safest form of nutrition for infants. Infants and breast milk are designed for each other. Infant formula has been developed to substitute for breast milk when nursing is impractical, or in the unusual instances when it is physically impossible or contraindicated. The goal for infant formulas is to match as closely as possible the composition of human breast milk.
Over the past few years, two key ingredients have been identified in breast milk, which, until 2002, were not present in the infant formulas available in the United States. DHA (docosahexaenoic acid) and ARA (arachidonic acid) are the most prevalent long chain fatty acids found in human breast milk. (These naturally occurring fatty acids are also found in fish oil.)
DHA and ARA are the most prevalent structural fats in the brain. Healthy brains are about 60% structural fat (not like the flabby fat found elsewhere in the body). Of this about 25% is DHA and 15% is ARA. DHA is also a major structural component of the retina of the eye. It makes up about 60% of the outer segments of the rods in the retina. Autopsies performed on babies who have died from other causes have shown that formula-fed babies have significantly less DHA in their brains than breast-fed babies.
A large number of studies have suggested that low DHA and ARA levels might be associated with problems with intelligence, vision, and behavior. Children fed standard formulas may have IQ’s 5-9 points lower than breast-fed babies, even after correcting for other factors. Vision is measurably poorer by 4 months of age (although this seems to equalize with age), and behavioral problems, such as attention deficit disorder, are more common. These discrepancies have not been found when infants are fed formulas supplemented with DHA and ARA.
Research funded by the National Institutes of Child Health and Development (NICHD) found that infants fed formula with DHA and ARA at the levels recommended by the World Health Organization scored approximately seven points higher on a 100-point scale on a test of mental development at 18-months compared to infants fed the control formula without added DHA and ARA. The study also found that infants fed formula with DHA and ARA at these levels had improved visual acuity equal to about one line on a vision chart during the first year.
Some studies of DHA and ARA have not detected these striking differences. The studies don’t contradict each other – they are just different. They use different amounts of DHA and ARA, different sources, and different methods to measure benefit.
Because parents are becoming more aware of DHA and ARA, more products containing them are coming to market. In fact, over the last few years, nearly all major brands of infant formula have supplemental DHA and ARA. Remember: just because a product has DHA and ARA on the label, it does not mean that the nutrients are present at the levels that have been clinically demonstrated to make a difference (the levels recommended by the World Health Organization and found in breast milk around the world).
A study published in the March 2002 issue of the American Journal of Clinical Nutrition showed that among babies who nurse for 6 weeks and then wean to formula, DHA and ARA in the formula at the right levels continues to make a difference. These babies were followed for a year, and throughout the study those babies who had the enhanced formula had better vision than those who had traditional formula.
During the months when infants are exclusively breast fed or formula fed (before supplemental feedings are introduced), they must get their nutrients from what they drink. As the variety of foods they eat increases, infants are able to obtain more of the nutrients they need from these foods.
Even then, breast milk is the foundation of optimal nutrition. I agree with the World Health Organization in urging mothers to breast feed exclusively for six months, and to continue to breast feed “for up to two years of age or beyond”. When babies do receive formula, I am thrilled that formula containing DHA and ARA is available.
I am very grateful for modern infant formulas. They provide the best alternative to breast milk ever available in history. More than that, though, this recent formula innovation underscores the value of breast milk itself, including benefits we have yet to discover.
Note: Dr. Greene has been writing on this issue since 1996 when his youngest child needed to switch to formula because of breast cancer. Dr. Greene wished formula with DHA and ARA was available for his son then. When the first formula with DHA and ARA was introduced in the U.S. in 2002, Dr. Greene served for a time as the national spokesperson, to educate physicians and parents about DHA and ARA.