NUTRIMENTHE's symposium at the Hotel New York, Rotterdam May 2012.
Maternal thyroid hormone plays a crucial role during development, lack of which results in mental retardation (Man et al 1976). During brain development, thyroid hormones are involved in the formation of the hippocampus and the migration of cells to the cortex, the ‘grey matter’ of the brain. Generation R has assessed the role of thyroid hormone in behavioural and emotional development and found that children born to women showing reduced levels of thyroid hormone, had a higher risk of developing expressive language delay at 18 months and 30 months. Expressive language includes the ability to form sentences, use grammar correctly, and retell a story or event. (References; Man and Serunian Am J Obstet Gynecol 1976; Ghassabian et al., Pediatric Research 2011; Henrichs et al., JCEM. 2010).
Maternal folate status and foetal head circumference.
Also collected from the Generation R cohort were ultrasound measurments from three points during pregnancy, to determine the growth of the head of the developing child. In the case of low maternal folate status, the head grows more slowly (0.1mm less per week compared to controls) As Dr Tiemeier explained, the difference actually equates to a lack of development of 1.9million neurons, per week. How does this potential lack of brain growth manifest itself later in life? To address this, MRI images were collected from children aged 6 to 8. No differences were found in the measurements taken from five different brain regions in children from low-folate status mothers compared to those that experienced 'normal' levels of folate. However, the central region of the corpus callosum (that connects the left and right sides of the brain) showed significant differences in size. In the future, Generation R plans to evaluate whether a combination of low folate status and a reduction in head development during pregnancy offers a reduced ability to deal with adverse environmental factors.Dr Eva Lattka, Helmholtz Zentrum Munich, German Research Centre for Environmental Health.
Fish intake and child mental devlopment.
Pauline Emmett from the Universtiy of Bristol presented work from the ALSPAC cohort and follow-on work conducted under NUTRIMENTHE. ALSPAC, the Avon Longitudunal Study of Parents and Children began as a cohort of 14000 pregant women, recruited between 1991 – 1992 in South West England. In 2007, work was published indicating that there is a link between seafood consumption in pregnancy and neurodevelopmental outcomes at age 8, in particular with respect to verbal IQ. Low maternal seafood intake is associated with an increased risk of suboptimum outcomes for verbal IQ, prosocial behaviour (giving, helping and sharing), fine motor, communication and social development scores. It may be that long-chain polyunsaturated fatty acids (LC-PUFA) and especially the omega-3 fatty acid, docosohexaenoic acid (DHA) contained in fish, is responsible for the beneficial effects of high fish intake. (References; Hibbeln et al., Lancet 2007).
Are Long-chain polyunsaturated fatty acids in fish related to better mental development?
Maternal levels of red blood cell DHA are related to the amount of oliy fish eaten during pregnancy. However, NUTRIMENTHE has found that these levels are not related to a child's verbal IQ and it may be other nutrients in fish that are mediating the effect, for example iodine, Vitamin D, selenium. This is currently under investigation by the project. The child's diet may also be important and genetic varients may modify the effects.
Contribution of genetics to fatty acid levels
NUTRIMENTHE is concerned with how polymorphisms in the fatty acid desaturase (FADS) gene cluster, that code for the enzymes involved in the synthesis of omega-3 and omega-6 fatty acids, influence how fatty acids are processed during pregnancy. 18 single nucleotide polymorphisms (SNPs) were genotyped from more than 10000 mothers and their children from the ALSPAC cohort. LC-PUFAs were analysed in maternal blood and in the umbilical cord at birth. Maternal seafood consumption was obtained by food frequency questionnaire. Dr Emmett demonstrated that maternal FADS genotypes are associated with LC-PUFA levels in maternal blood and that these associations are independent of dietary seafood intake. Both maternal and child FADS genotypes influence LC-PUFA levels in cord blood. DHA levels in the child are dependent on maternal and child metabolism.
Verbal IQ, breastfeeding and genetic effects
Finally, Dr Emmett presented further results showing how FADS genotypes and breastfeeding can influence a child’s IQ at age 8. Breastfed children performed similarly on the IQ test, irrespective of genotype but children carrying a particular ‘minor’ genetic variant in the FADS cluster, showed the biggest diferrence between the feeding groups and benefit most from being breastfed. This may be biologically plausible as breast milk contains preformed DHA and therefore all children should benefit from breastfeeding. (Reference; Steer et al., PLOS One 2010).
Diet and Mental Performance, what do parents think?
Dr Bernadette Egan from the University of Surrey, presented results from NUTRIMENTHE's consumer survey, of parents. Nutrition is one of many factors that will influence a child's mental development, other factors include environment and genetics. There is evidence in the scientific literature of the effects of diet on mental performance but very little published regarding parent’s perceptions of the relationship between a child’s diet and mental performance. Since parents are seen as nutritional gatekeepers, with responsibility for their children's diet thier views and beliefs are important. Interviews were conducted with parents of children aged 4-10 in four European Countries. Questions covered issues such as the extent to which a child’s attention and ability to learn are affected by a range of factors including food-related, factors important to parents when providing food for their children and what influences a parent’s decision regarding how to feed their children. Parents believe that diet affects aspects of children’s mental performance and this term is often spoken of in terms of 'attention' and 'concentration'. Other factors such as the provision of variety and overall healthiness of food, may be more important in the food choices parents make. (Reference; Brands et al., Appetite 2012).
Summary of key results emerging from the presentations.
- Advances in brain imaging techniques, epecially post acqisition analysis of MRI scans, will help to advance the in vivo study of the effect of nutrition on the human brain but, this will only be useful if nutrition actually affects the brain in a measurable way.
- Folate supplementation during pregnancy may protect against emotional and behavioural problems in young children.
- Low levels of maternal folate may impact on a child’s brain growth during pregnancy.
- Reduced levels of thyroid hormone during pregnancy can impact on a child’s language development
- There is a link between the amount of fish eaten during pregnancy and a child’s language development but, this may not be due the levels of omega-3 fatty acids in fish.
- An individual’s (child or mother) genetic make up influences how fatty acid’s are processed. Children showing a particular minor genetic variant in FADS genes, that were never breastfed, perform less well in an IQ test at age 8, compared to those that were.
- Parents as ‘nutritional gatekeepers’ for their children’s diet, do see a link between diet and mental performance, especially their ‘attention’ or ‘concentration’ Parents don’t discuss diet and mental performance in terms of the finer points of neurodevelopment.
- Professor Elizabeth Isaacs "Using neuroimaging to study the effects of nutrition on the brain"
- Dr Henning Tiemeier "Nutrition and neurodevelopment: Research in a population-based birth cohort"
- Dr Pauline Emmett "Genes, fish intake and child mental development: Results from a UK birth cohort (ALSPAC)"
- Dr Bernadette Egan "Diet and mental performance of children - what do parents think?"