Hi Toby,
I have no personal knowledge regarding your question about a patient with
abetalipoproteineamia, however I asked the opinion of a colleague who has
done his PhD in fats in breastmilk and infant growth. He is assuming (from
the abstracts you gave) that there is a deficit of lipoprotein lipase
associated with this condition. If this assumption is incorrect please
disregard the following response:

"With regard to the abstracts, I'm assuming that these mums don't have any
lipoprotein lipase.  This means that they can't get fats from their blood
into milk.  The breast, however, only makes fatty acids up to 14 carbons in
chain length whereas the longer (PUFA etc) fatty acids are all derived from
blood borne sources.  Thus explaining the high proportions of medium chain
length fatty acids mentioned in the second abstract.

I'm not sure of the effect, if any, this condition has on milk yield.
Should milk yield in these women be normal (which I can't think of a reason
why it shouldn't) it means that the infant may be getting milk of low fat
content (as mentioned in the second abstract) and the fatty acids that
comprise that fat will be predominantly medium chain length fatty acids.
To me it seems that under these circumstances the milk may mirror the
composition of many infant formulas which are also devoid of the longer
chain length polyunsaturated fatty acids.

The biggest concern will be whether the infant is receiving any of the
essential fatty acids (EFA).  Whilst adults only have 18:2n6 (linoleic
acid) and 18:3n3 (alpha linolenic acid) as acknowledged EFA, infants are a
bit different and recent evidence has suggested that for the neonate these
two plus 20:4n6 (arachidonic acid) and 22:6n3 (DHA) may  also be essential
for optimal development.  Lack of the two main EFAs is a big deal with,
among other things, growth being a major issue.  The other a bit more
intrinsic, with IQ, visual development and immunological properties being
key issues.

So these concerns need to be weighed up.  Ideally it would be good for
someone to analyse the milk to see what the fatty acid composition is, then
it would be easier to determine a  course of action.

Hope that helps.  Of course if these women don't lack lipoprotein lipase,
disregard everything I just said."

Regards
Cathy Fetherston
Western Australia

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