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Subject:
From:
"Rebecca Black, IBCLC" <[log in to unmask]>
Reply To:
Lactation Information and Discussion <[log in to unmask]>
Date:
Thu, 27 Jul 1995 07:22:32 -0400
Content-Type:
text/plain
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Forwarded message:
Subj:    RE:Allergies to milk proteins
Date:    95-07-24 20:12:25 EDT
From:    BLACKRF
To:      Listserv@librarylactnetdigest

I was lurking along enjoying the view when my favorite subject came
up:biochemistry of human milk (I know -UGH!!!).  I could no longer just lurk.
 There is some misconception about milk proteins and so I thought maybe this
was the time to jump on in....

There are two priniciple categories of milk proteins: caseins and whey.
 Casein makes up 20-40% of the the total protein in human milk and whey makes
up 60-80%.  Whey human milk proteins include alpha- lactalbumin
(0.2-0.4g.dl-1), lactoferrin (0.5-0.1 g.dl-1 -rises later in lactation
suggesting an adaptive mechanism), and secretory IgA (0.2-0.08g.dl-1- week 1
to week 12).  The individual variability is between 20-30% and concentrations
are related to parity.
 In contrast, bovine whey protein is predominantly beta-lactoglobulin
(considered by many the most allergenic protein in nature).

Human milk caseins are predominately of the beta type while bovine casein is
about 50% alpha-casein which is more phosphorylated.  Casein proteins form
micelles which include calcium and phosphorus and the high alpha-casein ratio
in bovine milk is one of the reasons that more iron must be added to
artificial baby milks to mimic the iron absorption from human milk (the
levels of citrate and vitamin C in human milk also play a role).

Therefore, it is highly likely that the infant in the case study discussed on
LACTNET JUly 23 as allergic to casein and whey could be allergic more to the
bovine sources.  However, individual amino acids can cause problems in some
inborn errors of metabolism due to an inability to metabolize the enzymes
needed for assimiliation so that could not be ruled out.  The best bet is
always to go to the MD and talk to him/her about the possiblity that the
problem is really one intrinsic to feeding artificial baby milk and not
breastmilk.  If you are in an academic environment it will usually be much
easier as these physicians actually welcome challenges as opportunities to
broaden their knowledge base.

Sorry if this is too technical but there seemed to be a need to clarify more
clearly the differences between the proteins in human milk vs. bovine milk.

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