Thanks Pam (and everyone else who has responded). My basic understanding is as people have written but it's the more technical explanation that I am looking for. I find it a bit surprising that it would be so seemingly difficult to find!
Karleen Gribble
Australia
On 17/01/2015, at 9:44 PM, Pamela Morrison wrote:

> Karleen
> 
> Have you read Maureen Minchin's books, Nursing Matters and Food for 
> Thought?  And I believe there will be another one out soon which I'm 
> _very eager_ to read....
> 
> Just very crudely, I understand that the infant gut is porous for the 
> first 4 months of life, and if exposed to "foreign" proteins 
> (anything other than breastmilk) then these proteins can be absorbed 
> into the bloodstream where they can set up a sensitivity which can 
> last for life.  If such an infant grows up to be a nursing mother who 
> is herself sensitive to a particular kind of protein - say - peanuts 
> - she can then secrete peanut proteins in her milk where they can 
> sensitize the baby.  If, however, she eliminates peanuts from her 
> diet, particularly before the baby's own gut closure would normally 
> occur, at about 16-17 weeks, then the baby will not be exposed, and 
> will not show sensitivity to the same proteins as an adult.  The 
> protein that we in the western world are so over-exposed to too early 
> is of course cow's milk, because so few of us have been exclusively 
> breastfed for the recommended period of the first 6 months of 
> life.  I think I read that Maureen believes that a sensitivity to 
> bovine proteins could be eliminated in two generations if a mother 
> exclusively breastfeeds her daughter, and that daughter exclusively 
> breastfeeds her own daughter.
> 
> Of course, this could be a completely off-the-wall mish-mash of 
> misunderstanding!  And I too would welcome a really technical 
> explanation, with refs :-)
> 
> Pamela Morrison IBCLC
> Rustington, England
> 
> 
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