To evaluate the developmental outcomes of children who participated in an augmented randomized clinical trial of supplementing a standard infant formula with long-chain polyunsaturated fatty acids.


Randomized clinical trial, augmented with a nonrandomized human milk comparison group. There were three randomized formula groups: standard formula, standard formula containing docosahexaenoic acid (DHA), and standard formula containing DHA and arachidonic acid.


Three clinical sites serving diverse populations: Kansas City, MO; Portland, OR; and Seattle, WA.


A total of 274 healthy full-term infants were enrolled in the infant-feeding protocol; of these, 197 (72%) participated in assessments of developmental outcome.

Formula Supplements.

In the randomized trial, one group received a standard formula, another group received a formula that had been supplemented with DHA from fish oil, and a third group received a formula supplemented with both DHA and arachidonic acid from an egg phospholipid.

Outcome Measures.

Mental and Motor Scales of the Bayley Scales of Infant Development at 12 months of age; vocabulary and gesture communication scores from the MacArthur Communicative Development Inventories at 14 months of age.


There were no statistically significant differences for either the Bayley Mental Scale or the Bayley Motor Scale, neither when the analysis was restricted to the three randomized formula groups nor when the analysis included all four groups. However, the DHA formula group had significantly lower scores on two of the MacArthur scales: the DHA group scored lower than the nonrandomized human milk comparison group on the Vocabulary Comprehension Scale, and the DHA group scored lower than the randomized control formula group on the Vocabulary Production Scale. Moreover, additional analyses both in the formula groups and in the human milk comparison group found significant negative correlations between DHA levels and vocabulary outcomes.


We believe that additional research should be undertaken before the introduction of these supplements into standard infant formulas.

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