From the above site (Dr. Sears) I am posting a portion that will help :
The most rapid brain growth occurs during the first year of life,
with the infant's brain tripling in size by the first birthday.
During this stage of rapid central nervous system growth,
the brain uses sixty percent of the total energy consumed by the infant.
Fats are a major component of the brain cell membrane and the myelin sheath
around each nerve. So, it makes sense that getting enough fat,
and the right kinds of fat, can greatly affect brain development and
performance. In fact, during the first year, around fifty percent of
an infant's daily calories come from fat. Mother Nature knows how
important fat is for babies; fifty percent of the calories in mother's milk is fat.
The body needs two kinds of fat to manufacture healthy brain cells
(the message senders) and prostaglandins (the messengers).
These are omega 6 fatty acids (found in many oils, such as
safflower, sunflower, corn, and sesame oils) and omega 3 fatty acids
(found in flax, pumpkin seeds and walnuts, and coldwater fish, such as salmon and tuna).
Just how important is DHA for brain development?
Consider these research findings:
• Infants who have low amounts of DHA in
their diet have reduced brain development and diminished visual acuity.
• The increased intelligence and academic performance
of breastfed compared with formula- fed infants has been
attributed in part to the increased DHA content of human milk.
• Cultures whose diet is high in omega 3 fatty acids
(such as the Eskimos who eat a lot of fish) have a lower incidence
of degenerative diseases of the central nervous system, such as multiple sclerosis.
• Experimental animals whose diets are low in DHA have
been found to have smaller brains and delayed central nervous system development.
• Some children with poor school performance because of ADD,
have been shown to have insufficient essential fatty acids in their diet.
(See A.D.D. - A Nutritional Deficiency?)
Hope this helps!