Nuts-rich diet in first trimester linked to improved neuro-development in child

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Nuts are known to help reduce the risk of hypertension, oxidative stress and diabetes and they may exercise a protective effect against cognitive decline in older age. To this list of beneficial health effects, we can now add new evidence from a study led by the Barcelona Institute for Global Health (ISGlobal), an institute supported by “la Caixa”. The study found links between a maternal diet rich in nuts during the first trimester of pregnancy and improved neuro-development in the child.

The study was carried out in Spain and included over 2,200 mother and child pairs enrolled in cohorts belonging to the INMA Project located in Asturias, Guipuzcoa, Sabadell and Valencia. Information on maternal nut intake was obtained from questionnaires on eating habits, which the mothers completed during the first and last trimester of their pregnancy. The children’s neuro-psychological development was assessed using several internationally validated standard tests 18 months, 5 years, and 8 years after birth.

Analysis of the results showed that the group of children whose mothers ate more nuts during the first trimester of pregnancy obtained the best results in all the tests measuring cognitive function, attention capacity and working memory.

“This is the first study to explore the possible benefits of eating nuts during pregnancy for the child’s neuro-development in the long term. The brain undergoes a series of complex processes during gestation and this means that maternal nutrition is a determining factor in foetal brain development and can have long-term effects, explains Florence Gignac, ISGlobal researcher and first author of the study. “The nuts we took into account in this study were walnuts, almonds, peanuts, pine nuts and hazelnuts. We think that the beneficial effects observed might be due to the fact that the nuts provided high levels of folic acid and, in particular, essential fatty acids like omega-3 and omega-6. These components tend to accumulate in neural tissue, particularly in the frontal areas of the brain, which influence memory and executive functions.”

The benefits described in this study were observed in the group of mothers who reported the highest consumption of nuts – a weekly average of just under three 30g servings. This is slightly lower than the average weekly consumption recommended in the healthy eating guide published by the Spanish Society of Community Nutrition (SENC: Guía de la alimentación saludable), which is between three and seven servings per week. “This makes us think that if the mothers consumed the recommended weekly average the benefits could be much greater,” Gignac explains. Estimated nut consumption in Spain is more than double the European average (4.8g vs. 2.2g).

The study also analysed the mothers’ nut consumption during the third trimester of their pregnancy, but in this case either no associations were observed with the neuro-psychological outcomes or the associations found were weaker.

“This is not the first time we have observed more marked effects when an exposure occurs at a specific stage of the pregnancy. While our study does not explain the causes of the difference between the first and third trimesters, the scientific literature speculates that the rhythm of foetal development varies throughout the pregnancy and that there are periods when development is particularly sensitive to maternal diet” explains Jordi Júlvez, ISGlobal researcher and last author of the study.

“In any case,” adds Júlvez, “as this is the first study to explore this effect, we must treat the findings with caution and work on reproducing them in the future with more cohort studies as well as randomised controlled trials.”

Abstract
There is scientific evidence on the protective effects of nut intake against cognitive decline in the elderly; however, this effect has been less explored in child neurodevelopment and no studies have explored the potential longitudinal association with nut intake during pregnancy. We aimed to analyze the association of maternal nut intake during pregnancy with child neuropsychological outcomes. We included 2208 mother–child pairs from a population-based birth cohort in four regions of Spain. The follow up settings were during pregnancy (first and third trimesters), birth, 1.5, 5 and 8 years. Neuropsychological examinations were based on Bayley Scales of Infant Development (1.5 years), McCarthy scales of Children’s Abilities (5 year), Attention Network Test (ANT, 8 year) and N-Back test (8 year). Nut intake in pregnancy was reported through a validated food frequency questionnaire during the first and the third trimester. Multivariable regressions analyzed associations after controlling for priori selected confounders notably maternal education, social class, body mass index, energy intake, fish intake, omega-3 supplements, alcohol consumption and smoking habits during pregnancy. Children within the highest tertile of maternal nut consumption during first pregnancy trimester (> 32 g/week) had a decrease of 13.82 ms [95% confidence interval (CI) − 23.40, − 4.23] in the ANT—hit reaction time standard error, compared to the first tertile (median 0 g/w). A similar protective association pattern was observed with the other cognitive scores at the different child ages. After correcting for multiple testing using Bonferroni familywise error rate (FWER), Hochberg FWER and Simes false discovery rate, ANT—hit reaction time standard error remained significant. Final model estimates by inverse probability weighting did not change results. Third pregnancy trimester nut intake showed weaker associations. These data indicate that nut intake during early pregnancy is associated with long-term child neuropsychological development. Future cohort studies and randomized clinical trials are needed to confirm this association pattern in order to further extend nutrition guidelines among pregnant women.

Authors
Gignac F, Romaguera D, Fernández-Barrés S, Phillipat C, Garcia-Esteban R, López-Vicente M, Vioque J, Fernández-Somoano A, Tardón A, Iñiguez C, Lopez-Espinosa MJ, García de la Hera M, Amiano P, Ibarluzea J, Guxens M, Sunyer J, Julvez J

Barcelona Institute for Global Health material
European Journal of Epidemiology abstract


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