Impact of omega-3 fatty acid DHA and EPA supplementation in pregnant or breast-feeding women on cognitive performance of children: systematic review and meta-analysis.

INTRODUCTION: The omega-3 long-chain polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are important for brain development and cognitive performance. Because they are semi-essential fatty acids, they must be obtained from food. However, the dietary reference intakes of DHA and EPA have not yet been established. In women, a low DHA and/or EPA serum level during pregnancy or breastfeeding might negatively affect their children. For this study, we conducted a systematic review and meta-analysis of randomized control trials on the association between the consumption of fish oil supplements in pregnant and/or breastfeeding women and the cognitive performance of their children. METHODS: The PubMed, Embase, and Central literature databases were systematically searched. We included and extracted relevant studies in duplicate and assessed study quality. Cognitive outcomes were grouped according to published criteria and according to time elapsed after the intervention. We performed fixed-effects meta-analyses for each cognitive outcome and for birth weight. We assessed potential confounding with meta-regressions and sensitivity analyses. RESULTS: A total of 11 trials were included. No significant association was found between DHA/EPA supplementation and any of the assessed cognitive parameters or birth weight. DISCUSSION: Our results confirm previous reviews on the studied topic. Reasons for inconclusive results may be small sample sizes for each assessed category, questionable quality of included studies, and the difficulty of reliably measuring cognitive performance in small children. Blood levels of omega-3 long-chain polyunsaturated fatty acids were mostly not comparable. Furthermore, the influence of genetic and environmental factors could not be assessed. Studies in this field should address such shortcomings.

Fish consumption is associated with school performance in children in a non-linear way: Results from the German cohort study KiGGS.

INTRODUCTION: How the long-chain fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in the diet permitted human brain evolution, and how much our brains need today to function optimally are still hot topics for debate. DHA and EPA are considered as semi-essential because only insufficient amounts can be produced from other nutrients, such that they must be ingested with the diet. However, the Dietary Reference Intake of DHA and EPA, or of fish containing these fatty acids, has not yet been established. Eating fish is often recommended and generally considered beneficial for health and cognitive development in children and adolescents. For this study, data from a large cohort study were analysed to assess the association between fish consumption and cognitive school performance in children and adolescents. METHODS: Data from the German cohort of children and adolescent health KiGGS, which was conducted 2003-06 and included more than 17 000 children, were analysed. Ordered logistic regressions were performed to test for associations between fish intake and school performance. Potential confounders were included in the models. RESULTS: A statistically significant association was found between an intake of 8 g of fish per day and the probability of increasing the final grade in German [odds ratio (OR) 1.193, 95% confidence interval (CI) 1.049-1.358] and mathematics (OR 1.16, 95% CI 1.022-1.317) by one point, compared to no or very limited fish consumption. For the outcome German, higher levels of fish intake also showed a positive effect. These relationships were not linear but tended to decrease again at higher doses of fish. DISCUSSION: Our result confirms previous reports of a positive association between fish intake and school performance. Interestingly, this relationship was not linear but tended to decrease again in the highest categories of fish intake. We hypothesize that mercury or other pollutants in the fish could be detrimental at high levels. As only half of all children met the minimal fish intake recommendations, fish consumption should be promoted more strongly in children to meet the minimal requirements of long-chain polyunsaturated fatty acids. LAY SUMMARY: Polyunsaturated fatty acids like DHA and EPA that are present in fish are essential for a healthy human brain development. We found a U-shaped association between fish intake and school performance in children. We hypothesize that mercury or other pollutants in the fish could be detrimental at high intake levels.