The DIAMOND (DHA Intake And Measurement Of Neural Development) Study: a double-masked, randomized controlled clinical trial of the maturation of infant visual acuity as a function of the dietary level of docosahexaenoic acid

Background: The range of human milk docosahexaenoic acid (DHA) concentrations worldwide is much broader than the range explored in randomized clinical trials to date. Objective: The primary objective was to determine the effect of 4 amounts of DHA supplementation on the visual acuity of formulafed infants at 12 mo of age. Secondary objectives were to evaluate visual acuity maturation, red blood cell fatty acids, tolerance, anthropometric measures, and adverse events. Design: This double-masked, randomized trial was conducted at 2 sites (Dallas and Kansas City). Three hundred forty-three healthy, term, formula-fed infants were enrolled at 1–9 d of age and were randomly assigned to be fed 1 of the following 4 infant formulas containing equivalent nutrient amounts, except for long-chain polyunsaturated fatty acids: control (0% DHA), 0.32% DHA, 0.64% DHA, or 0.96% DHA; DHA-supplemented formulas also provided 0.64% arachidonic acid. Visual acuity was measured by visual evoked potentials in 244 infants who completed the 12-mo primary outcome examination. Results: Infants fed control formula had significantly poorer visual evoked potential visual acuity at 12 mo of age than did infants who received any of the DHA-supplemented formulas (P , 0.001). There were no significant differences in visual evoked potential visual acuity between the 3 amounts of DHA supplementation for either site at any age tested. Conclusions: DHA supplementation of infant formula at 0.32% of total fatty acids improves visual acuity. Higher amounts of DHA supplementation were not associated with additional improvement of visual acuity. This trial was registered at clinicaltrials.gov as NCT00753818. Am J Clin Nutr 2010;91:848–59.