hello Lactnetters.  I am new to Lact net  and want to respond to this
question though I suspect there are others with more thorough
knowledge.

To introduce myself, I have had a long standing interest in lactation
having been a LLL Leader about 20 years ago  and and done some
lactation research. I  am privileged to serve on the Advisory board for
LLLI  and  as the Liaison with LLLI for the ADA Perinatal Nutrition
Practice group  and am on the NPA Board.  I am an RD faculty member at
Ball State University and  the Dean for Continuing Education.  I teach a
graduate course in Maternal and Infant Nutrition.

Lipids are such an important source of energy to the grapidly growing
infant and are very well absorbed from human milk.  It is my
understanding that cow milk fat is not well absorbed so loss of calories
could interfer with growth.  In an effort to improve  fat absorbtion
vegetable fats are substituted  because the  longchain polyunsaturated
fatty acids  are quite well absorbed and provide significant  energy.
I believe aconsiderable part of this research was done  by Dr.  Filer  who
has worked with Dr. Fomon's group in Iowa.

The vegetable lipids do not provide  the  very longchain  polyunsaturated
fats found in human milk and thought to be beneficial  to central nervous
system development,  especially important  in  the preterm infant.
Particular interest currently centers on  lipids such as DHA
-docosahexaenoic acid,  which  is thought to be critical  to CNS
development and is found in human milk.