A randomised control trial in schoolchildren showed improvement in cognitive function after consuming a bread spread, containing fish flour from a marine source

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Abstract

Background

In humans, n-3 long-chain polyunsaturated fatty acids play a well-documented role in brain development and function. Docosahexaenoic acid and arachidonic acid are major structural components of the brain and a deficiency thereof may bring about changes in the behaviour domains of the brain.

Objective

This trial investigated the effect of an experimental fish-flour bread spread rich in n-3 long-chain polyunsaturated fatty acids, on cognition of children (7–9 yr).

Design

Subjects (n=183) were randomly assigned to an experimental (n=91) and control group (n=92), receiving either the fish-flour spread or a placebo spread for 6 months in a single-blind study. Plasma and red blood cell phospholipid fatty acid composition and cognition were measured at baseline and post-intervention.

Results

After the intervention, eicosapentaenoic and docosahexaenoic acid levels were significantly higher in the experimental group compared to the control group (p< 0.0001). Significant intervention effects were also observed for the Hopkins Verbal Learning Test Recognition (estimated effect size: 0.80; 95% confidence interval (CI): 0.15; 1.45) and Discrimination Index (estimated effect size: 1.10; 95% CI: 0.30; 1.91), as well as the Spelling test (estimated effect size: 2.81; 95% CI: 0.59; 5.02) by both per protocol and intention to treat analyses. A marginally significant (p=0.0646) effect was observed for the Reading test (estimated effect size: 2.21; 95% CI: −0.14; 4.56) only in the per protocol analysis.

Conclusion

This study suggests improvement of verbal learning ability and memory of children when supplemented with a fish-flour spread rich in n-3 long-chain polyunsaturated fatty acids.

Introduction

Nutrition plays a well-documented role in brain development and, thus on, the cognitive development of children. As the brain has a high lipid content (∼60%), maintaining the special lipid composition of neuronal membranes is vital for the proper functioning of the central nervous system (CNS) [1]. Docosahexaenoic acid (DHA; C22:6n-3) and arachidonic acid (AA; C20:4n-6) form the basic components of cell membranes [2]. It is being hypothesized that DHA is particularly important for brain function as it maintains an optimal state of neural membranes, enabling membrane fluidity and thickness, which in turn affects cell signalling [3].

While the intakes of n-6 polyunsaturated fatty acid (n-6 PUFAs) are usually high on the Western type diet, the intakes of n-3 PUFAs are often inadequate. This influences the n-6:n-3 ratio in the diet negatively and may be especially of concern in growing children. Most of the research on the association between n-3 PUFA intake and cognitive development has focused on preterm infants or those with low birth weight. This focus is driven by what scientists believe to be the critical period of rapid brain growth and development, from gestation until the first 2 yr of life [4], [5]. Brain development is not, however, completed by the age of 2 yr, as certain brain areas are not yet fully developed [6], especially the frontal lobes of the brain, responsible for executive functions, which develop in spurts from birth to 2 yr, from 7 to 9 yr, and again in the mid-teenage years [6]. Therefore, poor nutrition may affect the developing functions of the frontal lobes of the brain throughout childhood [1], and intervention with LC-PUFAs can therefore influence brain development during these stages.

Very little is known about the effect of DHA supplementation, on the cognitive performance of school-age children. Learning problems have been found in 6–12-yr-old children with low n-3 PUFA concentrations in plasma phospholipids [7]. The effect of supplementation in this age group is not well known, with the NEMO Study reporting no effects of DHA and eicosapentaenoic acid (EPA) on factors of cognitive tests in a dual double blind randomised controlled trial done in Indonesia and South Australia [8]. A previous randomized placebo-controlled trial with an oil supplement rich in n-3 PUFA in South African primary schoolchildren (6–11 yr) over a 9-month period suggested an improvement in verbal learning and memory [9]. The aim of the current study was to investigate the effect of a non-commercial, specially formulated bread spread, containing n-3 PUFA-rich fish flour, on cognition of children (7–9 yr) in a single-blind randomised controlled trial for 6 months.

Section snippets

Study population and design

The study population consisted of Grade 2 children (7–9 yr) from a primary school serving a community with low socio-economic status and of mixed ancestry (African–European–Malay) from the Northern Cape Province of South Africa. Information collected by means of a short dietary questionnaire revealed virtually no intake of fatty fish and a very low intake of lean fish in this community (unpublished data). The parent or guardian of all subjects gave written informed consent for participation in

Results

Of the 183 children who were randomised for treatment, 164 completed the study (Fig. 1). The dropout rates were 11.0% (n=10) and 9.8% (n=9) for the experimental and control groups, respectively. Three children in the experimental group and four in the control group were not available for baseline cognitive tests. The dropout constituted the following subjects: those who could not or did not want to give blood; those who did not want to continue with the study (dislike); those who moved from the

Discussion

The current study suggests that the learning ability and memory of children aged 7–9 yr improved after supplementation with a fish-flour bread spread, containing LCPUFA (DHA and EPA) embedded in a natural food matrix. The study showed a significant intervention effect for HVLT Recognition and Discrimination index, as well as for the Spelling test in these children.

The specially designed bread spread used in this study supplied ca. 892 mg of DHA per week, which is equivalent to about 125 g or two

Acknowledgements

We wish to thank Emeritus Professor J.J. Du Preez (Faculty of Education, Stellenbosch University, Stellenbosch, South Africa), Professor E. Roets (Department of Educational Studies, School of Education, University of South Africa, Pretoria, South Africa), and Dr R. van Eeden (Department of Psychology, College of Humanities, University of South Africa, Pretoria, South Africa) for their invaluable contextual inputs with the interpretation of the cognitive results of this study. We also wish to

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    Research funding granted by The Department of Science and Technology Innovation Fund.

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