Malnutrition during the critical brain growth period, which lasts from the seventh foetal month until the age of 18 to 24 months, can have serious effects. Recent research has shown that children under two years of age are particularly vulnerable to brain damage as a result of poor nutrition and that such damage is often irreversible. At the same time, a child's development can be deeply affected by the lack of mental stimulation which is often associated with large families and a poverty-stricken environment.
In developing countries the young child suffers more than the adult from an unbalanced diet. Children between 1 and 3 years of age frequently suffer from protein deficiency, and they often suffer from the double insult of undernutrition and environmental deprivation - factors which almost certainly act synergistically in impairing brain growth.