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DHA During Pregnancy

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Study Finds Higher Doses of DHA in the Neonatal Period Improves Visual Acuity of Preterm Infants

A study in the October American Journal of Clinical Nutrition by Smithers et al. found that preterm infants born to Australian women who were fed human milk or formula containing 1% docosahexaenoic acid (DHA) until reaching their estimated due date had improved visual acuity over infants fed unsupplemented human milk or formula containing 0.2-0.4% DHA.1  The authors conclude that the “DHA requirement of preterm infants may be higher than currently provided by preterm formula or human milk of Australian women.”

The study was a double-blind randomized controlled trial that examined preterm infants born at less than 33 weeks of gestation.  143 infants were randomized within five days of receiving any enteral feedings to either a DHA supplemented group (lactating mothers were supplemented with a tuna oil capsule containing DHA to provide 1% DHA; formula fed infants were supplemented with 1% DHA) or a control group (nursing mothers supplemented with a soy oil capsule, and formula fed were fed formula with 0.2-0.4% DHA).  Fatty acids were measured in the serum of the infants and the infants in the treatment group exhibited significantly higher concentrations of DHA than the control group.  Visual acuity was assessed by the sweep visual evoked potential (VEP) using ENFANT 4010 software at both two and four months corrected age.  Although no differences in visual acuity were observed at two months of age, visual acuity at four months corrected age was higher in the DHA supplemented group than in the control group; no differences in anthropometry (weight, length, and head circumference) was observed between the two groups.

Strengths of the study include the use of a double-blinded, randomized clinical trial, incorporation of both human milk and formula into its design as well as adjusted analysis of variables.  The authors recognize that the clinical relevance of  the observed enhanced visual acuity with high-does dietary DHA needs to be evaluated;  follow up is warranted.   However, the findings of this study are consistent with other studies2-3 and suggest that “the improvement in acuity reported here represents an effect beyond that achieved by current best practice.”

1 Smithers, L.G., et al., Higher dose of docosahexaenoic acid in the neonatal period improves visual acuity of preterm infants: results of a randomized controlled trial. Am J Clin Nutr, 2008. 88(4): p. 1049-56.

2 Birch, E.E., et al., Dietary essential fatty acid supply and visual acuity development. Invest Ophthalmol Vis Sci, 1992. 33(11): p. 3242-53.

3  O'Connor, D.L., et al., Growth and development in preterm infants fed long-chain polyunsaturated fatty acids: a prospective, randomized controlled trial. Pediatrics, 2001. 108(2): p. 359-71.