EDITOR'S NOTE: The following press release describes a study that explored maternal diet during pregnancy, and the correlations between that diet and childhood measures of neuropsychological development. As in any correlative study, we ask our reader to consider other possible explanations for the correlation reported here. The authors of the paper have taken steps to rule out these explanations - by controlling for socioeconomic class of the mother, for example. This is good science and should be applauded. The paper itself, published in the European Journal of Epidemiology, mentions that after multiple testing corrections, which are needed in a study of this design, only a single neuropsychological measure, related to attention, remained significant. This calls into serious questions any claims that "intelligence" is affected by nut consumption in the first trimester of pregnancy. This is not addressed in the press release below, which we have included in full here:
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, published in the European Journal of Epidemiology, found links between a maternal diet rich in nuts during the first trimester of pregnancy and improved neuropsychological 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 neuropsychological 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 neuropsychological 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 fetal 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 (4.8 g vs. 2.2 g).
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 neuropsychological 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 fetal 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”.
This article has been republished from materials provided by ISGlobal. Note: material may have been edited for length and content. For further information, please contact the cited source.
Reference: Gignac, F., Romaguera, D., Fernández-Barrés, S., Phillipat, C., Garcia Esteban, R., López-Vicente, M., … Julvez, J. (2019). Maternal nut intake in pregnancy and child neuropsychological development up to 8 years old: a population-based cohort study in Spain. European Journal of Epidemiology. https://doi.org/10.1007/s10654-019-00521-6