Brain Development – Zero to Two: Nestle
Human brain development begins in the third gestational week and extends through adolescence. Number of neuron cells increase most rapidly between 25 and 40 weeks of gestation. The most critical developmental period of brain function occurs between last trimester and the first two years of life. Brain volume doubles between birth and six months of age, triples from birth to two years and reaches adult volumes by five years. Therefore, brain growth during infancy and early childhood is more important than growth during foetal life in determining the cognitive function of the child. There are various nutrients that have a significant effect on early brain development. They are micronutrients like protein, LC-PUFA micronutrients like iron, zinc, copper, iodine and vitamins like A, B, K, and others. A look at PUFA reveals that they play an important role in the functioning of cell membranes. Sufficient and balanced ALA and LA are important for normal development. ALA and LA are the precursors of DHA and AA, which are structural building blocks of the cerebral nerve cell membranes. LC-PUFA deficiency leads to abnormal behaviour including visual speed of processing. Brain also needs Iron to create energy, neurotransmitters and myelin. Energy is in the form of ATP which is made by cytochromes. Iron is also needed to make dopamine, serotonin and norepinephrine. Iron containing enzymes are needed to make fatty acids in myelin. Iron deficiency causes behaviour abnormalities like poorer recognition memory in new-borns, ischemic stroke and restless leg syndrome. Anaemia is a late sign of iron deficiency. It signifies that the brain has already been affected. Brain needs zinc because it interacts with the DNA. It is needed for growth factor synthesis, it is also needed for neurotransmitter release, autonomic nervous system development etc. A deficiency in zinc demonstrated decreased foetal movement, decreased heart rate variability and altered autonomic nervous system stability. Iodine is required for the synthesis of thyroid hormones. Iodine deficiency is the cause of avoidable early childhood brain damage and mental retardation. It also decreases brain functioning. Severe deficiency during the foetal and neonatal period leads to irreversible brain damage. Mid to moderate deficiency affects cognition.Choline is an essential nutrient for humans. It is a substrate for neurotransmitters and likely has epigenetic effect. It also promotes larger neuronal size, more dendritic absorption and greater neuronal signalling. Vitamins play an important part in the brain development. They can avoid Beri-Beri, epilepsy neural tube defects, blindness etc. Neural tube defects include anencephaly, Spina Bifida Occulta Cystica etc. This defect is higher in some states. Protein energy is required for cell proliferation, cell differentiation, synaptogenesis and the circuitry affected is global, cortex and hippocampus respectively. Iron is required for myelin dopamine, energy and the circuitry affected is white matter, striatal frontal and hippocampal frontal respectively. Zinc is required for DNA and neurotransmitter release and affects ANS hippocampus and cerebellum. Lastly, LC-PUFA is required for synaptogenesis and myelin and the circuitry affected is eye and cortex.