Arun and Rachna Malhotra were brilliant students. But now, they are the extremely-worried parents of a five-year-old whose IQ level is lower than children of the same age.

Like the Malhotras, most Calcuttans hold a misconception that intelligence is purely hereditary. Doctors say it is the composition of the child?s daily diet that affects his/her brain development.

?These days, parents are worried about their children?s intelligence level. A diet rich in omega 3 and omega 6 fatty acids can go a long way in developing the brain to the optimum level during the first three years after birth. The fatty acids are found mostly in oily fish, fish oils and even in milk,? says city-based paediatrician B.K. Manocha.

?The problem of slow-development of IQ level is also common in low birth-weight babies,? he explained.

The development of the nervous system occurs primarily during pre-school days. During this critical stage, a child acquires new skills and gathers intelligence in learning complex social groupings and understanding new things.

?The size of the human brain at birth is almost 70 per cent that of an adult. Fifteen per cent of the brain growth occurs during infancy, and the rest during the pre-school years. Thus, the maximum brain growth is completed by the time the child is five years old,? said Meherban Singh, former head of paediatrics, All India Institute of Medical Sciences (AIIMS), quoting recent WHO studies.

Sixty per cent of the brain is composed of fat, essentially of fatty acids (omega 3 and omega 6). Experts say docosahexaenoic acid (DHA), which constitutes 25 per cent of the total fatty matter in the brain, is a key component.

?Hence, a diet rich in DHA has a big role in the development of the child?s brain. The brain development continues till about the age of eight. But, above the age of three, the growth would be synonymous to adding bricks to an already-laid foundation,? explained Apurba Ghosh, director of the Institute of Child Health, who has been working on child behaviour and growth for many years now.

A lack of essential vitamins, minerals and fatty acids, infections and food allergies can exacerbate restlessness, poor concentration, clumsiness and learning difficulties. ?The right diet can help increase the mental development index, intelligence and proper functioning of the nervous system,? Ghosh added.