During prenatal period, various nutrients are critical for the overall development of the foetus especially brain development. The critical role of these nutrients continues in the post-natal period till the age of 5 years. About 70% of the adult brain size occurs in the initial 2 years of life. Thus, the pace at which brain develops during this period is maximum in comparison to its development for the rest of life. Any insult: environmental, physical or nutritional during the initial 2 years therefore, can have long term consequences.
Brain development in infancy and early childhood
If we look at the brain development closely, it would be justifiable to say that brain is not a homogeneous organ. It consists of multiple regions, each with differently timed developmental onsets. Nutrients that support brain development are distributed regionally to the areas exhibiting the most rapid growth at a given time in life.
Critical and sensitive periods in brain development
There are essentially two crucial periods of brain development: the critical periods and the sensitive periods. The critical period is a time-period when a particular part of the brain is most easily influenced or vulnerable to the lack or presence of stimulation or to environmental effects; and any injury to the brain during this period is irreversible. On the other hand, the sensitive period describes epochs where the brain is particularly receptive to stimuli, usually over a broader period of time.
Role of various nutrients in brain development
All nutrients hold their importance depending on the region and timing of brain development. Nutrients that support development are distributed regionally to the areas of most rapid growth at a given time in life. Some of these nutrients include iron, zinc, long-chain polyunsaturated fatty acids, iodine and copper. Deficiency of any of these important nutrients may lead to irreversible neurodevelopmental outcomes.
Iron is among one of the many important nutrients required for brain development
Iron is required during last trimester of gestation and during the post-natal period of 6 months- 3years. During this time, the developing brain requires iron for proteins which regulate myelin production, neurotransmitter synthesis, and neuronal energy production. These processes in turn, support the speed of processing in the brain, as well as emotions, learning, and memory.
Role of iron in brain development
Iron is important for rapidly multiplying or differentiating tissues. Therefore, unlike the slower growing brain of later infancy and childhood, the rapidly growing foetal-neonatal brain exhibits higher iron requirements.
Long term impact of iron deficiency
The most obvious clinical manifestation of iron deficiency is the neurodevelopmental effects. A study by Lukowski et al. reported long- term impact of iron deficiency in the form of cognitive deficits 10 to 20 years after the iron deficient insult during infancy.
Iron-rich foods should be given in early childhood
During the first 6 months of life, infants are self-sufficient with regard to iron. Therefore, exclusive breast-feeding during this period is sufficient to meet the infant’s iron requirements regardless of the low iron content in breast milk (0.3 mg/L). However, due to rapid growth between 6 and 24 months of age, iron requirements increase and the infant requires additional iron. Feeding infants with iron-rich foods is essential to meet their growing iron-requirements.
Micronutrients are critical for brain development in the first 1,000 days of life. The effect of micronutrient deficiencies is likely to have irreversible effect on neurobehavioral development. Therefore, foods rich in micronutrients especially iron should be included and offered to the child as a part of complementary foods.