>This has come up several times in the last two weeks.  And it is driving me
>nuts.  Somewhere out there doctors are telling mothers that since antibodies
>are proteins they are digested so therefore it doesn't matter if baby is
>breastfed or formula fed.  ARGH
>OK now we all agree that breastmilk provides protection because of the
>antibodies.  So what do I tell people about the antibodies?  Why or how aren't
>they digested?
>Marie

The vast majority of antibodies in breastmilk are IgA type, otherwise known
as 'secretory IgA'. These have a special section, the J-chain, if I
remember my immunology correctly, which joins two units (like individual
antibodies of the IgG class) together. This makes them very resistent to
being broken down. Secretory IgA are the antibodies associated with mucous
membranes, etc and 'outside' conditions - therefore they are 'tough'. I
think that is what makes them resistent to digestion. They go into the
baby's gut and act like 'paint' on the surface of the intestines. In a
similar way they coat the lining of the lungs, etc in all normal people and
act as the first (antibody) line of defense. Interestingly, there are
people who are IgA-deficient who can live apparently normal lives. I wonder
how they go with protection of their breastfed babies??

Someone else may be able to explain this a little more scientifically -
this is just my recollection of how it works. Anyone know any more about
IgA-deficient mothers and their babies? Would be fascinating.

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Joy Anderson B.Sc. Dip.Ed. Grad.Dip.Med.Tech. IBCLC
Nursing Mothers' Association of Australia Breastfeeding Counsellor
Perth, Western Australia.   mailto:[log in to unmask]
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