Originally posted by: Paperdoc
There is a lot of confusion about milk allergies. The two most common are lactose intolerance (not really an allergy) and true allergy to the proteins in milk.
You're really close, so here's a bit more. Milk problems run in my husband's family. Lactose intolerance is often genetic - my husband's family and ethnic group - and most Asian and African Americans, for example. Most babies have some lactose tolerance (lactase, the enzyme required to digest lactose), but in many people it fades. Merely continuing to drink milk won't extend the lactase production if someone is lactose intolerant.
And yes, there are babies who cannot tolerate their mother's milk. Sometimes it's congenital lactase deficiency - babies without lactase. There's also something called galactosemia which is an inability to use galactose, which is related to the whole lactose thing. As I say, this stuff runs in the family (husband's newborn brother died of it).
Galactosemia is one of the things they look for in the heel-blood thing they do with newborns.
Regarding milk allergies: the most common allergies are to the two proteins in milk, whey and casein. You can be allergic to either protein or both at the same time. In addition, there is a milk fat allergy, much less common than a milk protein allergy. Some people with milk protein allergy can tolerate milk fats (i.e. clarified butter). Some people with milk fat allergy can tolerate milk proteins (i.e. fat-free milk).
Goat's milk lacks the major casein (there are several) in cow's milk. That's why some, but not all, people who have milk protein allergies can tolerate goat's milk. Also, goat's milk is not lactose-free, but it is digested more completely than cow's milk, so many people with mild lactose intolerance can tolerate it - less lactose needed to digest.
Often, milk allergies in children are outgrown. Lactose intolerance becomes more and more probable as people age.
Also, some people with milk allergies are also allergic to beef, leather, etc.
I know, way too much information. But for those of us who deal with milk issues, very important to get it right.
edited because I misspelled milk once. As long as I'm editing, let me add this (which confuses many people)
the thing that "lactose intolerant" people can't digest is lactOse - with an "o". OOOOOOOhhh, my belly hurts.
the thing that digests lactose is lactAse - yAAAAAAAAAAAAAAAAAAy!