Review
Effects of n-3 long chain polyunsaturated fatty acid supplementation on visual and cognitive development throughout childhood: A review of human studies

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Abstract

The present paper evaluates the most recent randomized controlled trials assessing the efficacy of n-3 LCPUFA supplementation (with or without n-6 LCPUFA) during pregnancy, lactation, infancy and childhood on visual and cognitive development.

Available evidence suggests a beneficial effect of maternal n-3 LCPUFA supplementation during pregnancy and lactation on cognitive development of infants and children, but not for visual development. Evidence for an effect of LCPUFA supplementation of preterm and term infants on cognitive development of infants remains inconclusive. However, supplementing term infants with daily doses of 100 mg docosahexaenoic acid plus 200 mg arachidonic acid improves visual development as measured by electrophysiological tests. Evidence for benefits of n-3 LCPUFA on cognitive development in healthy children older than 2 years of age is too limited to allow a clear conclusion. Taken together, the evidence for potential benefits of LCPUFA supplementation is promising but yet inconclusive.

Introduction

There is considerable interest in the role of certain long chain polyunsaturated fatty acids (LCPUFA), in visual and cognitive development throughout childhood. The n-3 fatty acid docosahexaenoic acid (DHA) and the n-6 fatty acid arachidonic acid (AA) are the major LCPUFA in the brain [1]. DHA and AA are rapidly incorporated in the nervous tissue of retina and brain during the brain's growth spurt, which mainly takes place from the last trimester of pregnancy up to 2 years of age [1], [2], [3], [4]. Beyond development of the central nervous system, n-3 and n-6 fatty acids may influence brain function throughout life by modifications of neuronal membrane fluidity, membrane activity-bound enzymes, number and affinity of receptors, function of neuronal membrane ionic channels, and production of neurotransmitters and brain peptides [5]. Although DHA and AA are the major structural components of the central nervous system, there is currently no consensus whether dietary supplementation of LCPUFA has benefits for visual and cognitive development of infants. Two Cochrane reviews conclude that for preterm infants, there are no positive long-term effects (>6 months of age) of LCPUFA on visual or intellectual development, while evidence for a beneficial effect of LCPUFA supplementation on early visual development of preterm infants (<6 months of age) is inconclusive [6]. For term infants there is little evidence for a benefit of LCPUFA supplementation on visual or general development [7]. Recently, McCann and Ames [8] reviewed evidence from human and animal studies to assess whether DHA is required for development of normal brain function. They concluded that evidence is too inconsistent to conclude that infant formula should be supplemented with DHA.

Since publication of the Cochrane reviews and review by McCann and Ames, several new human intervention studies on this topic appeared in literature. Additionally, new research focused on the effect of maternal n-3 LCPUFA supplementation during pregnancy and lactation on visual and cognitive function of infants. In this paper, we therefore aim to re-evaluate the currently available evidence on the effect of LCPUFA on visual and cognitive function during infancy and later childhood. We focus on human nutrition intervention studies on LCPUFA supplementation during pregnancy, lactation, infancy and childhood.

Section snippets

Literature search

For assessment of the effects of LCPUFA supplementation on visual and cognitive development of children, we divided the literature into four topic areas:

  • 1.

    Supplementation of mothers during pregnancy and lactation and effects on visual and cognitive development of their infants.

  • 2.

    Supplementation of preterm infants during the first two years of life and effects on their visual and cognitive development.

  • 3.

    Supplementation of term infants during the first two years of life and effects on their visual and

Maternal n-3 LCPUFA supplementation and effect on visual and cognitive development of their neonates

Six studies have been found in literature assessing the effect of maternal supplementation during pregnancy and/or lactation with n-3 LCPUFA on visual and cognitive development of their infants. The characteristics of these trials are shown in Table 1.

Acknowledgments

We are grateful to G. Hornstra, Nutrisearch, Gronsveld, The Netherlands for providing critical comments on the manuscript.

Contributions: AE and DCH searched the literature. AE analyzed the literature and wrote the manuscript. CT contributed to interpretation of the literature. DCH, CT, SJO and PLZ critically reviewed and edited the manuscript.

Disclosure: All authors are employees of Unilever. Unilever markets food products, some of which are enriched with omega-3 fatty acids.

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