Formula Fantasies - a favorite topic of mine!
Standard infant formulas made from cow's milk must have the butterfat in them
removed because butterfat is poorly absorbed in human babies. Plant fats are
substituted and are typically blended to provide somewhere between 45%-58% of
the energy intake. Corn oil, coconut oil, palm oil, safflower oil, etc are
used to provide varying amounts of numerous fatty acids. They are a cheap
source of well absorbed fats. Fatty acids are the building blocks of fat,
just like amino acids are the building blocks of protein. These blended fats
however, do not contain the very long chain polyunsaturated fatty acids
(LCPUFA)so prevalent in the human brain and retina. Human milk of course
contains these fatty acids.

Two of these LCPUFA, called docosahexaenoic acid (DHA) and arachidonic acid
(AA) are currently the subjects of scads of papers on whether these should be
designated as essential in the diet of infants. DHA is the fatty acid which
is thought to be responsible for the better cognitive functioning in
breastfed infants. In the advertising of infant formula you will never see
these two fatty acids mentioned because they do not occur in any US formula.
They have been added to some formulas in Europe. These fatty acids were
derived from marine algae, not human sources!

Several review articles are quite specific in that "...there is little doubt
that there is a short term effect of DHA deficiency on efficiency of synaptic
transmission during a critical period of brain development and learning."
Formula fed babies also lack cholesterol in their feeds. All this fat is what
forms the myelin sheath around nerve tissue. If babies do not receive DHA and
AA directly from their diets then they need to make it. Most term babies and
all preterm babies cannot do this. The brains of formula-fed babies
substitute shorter chain fatty acids in place of the LCPUFA. The chemical
composition of the brains are different.

Formula companies may advertise how close their concoctions are to
breastmilk, but even the fake DHA/AA stuff had problems in clinical trials.
This stuff must be in the proper ratio. Early trials of the fake LCPUFA
experimented with not only the source of the fatty acids but also the ratio.
Some of the babies who received the experimental formulas with too much AA
scored significantly lower on cognitive tests at one year of age than the
controls and the other experimental groups. Why do commercial interests think
they can duplicate human milk? How many babies have been harmed in these
clincal trials? At least they got all the test formulas for free.