Posted 8/13/2011 2:41 PM (GMT 0)
Lactose is the sugar in all milk, and it is digested by the body using an enzyme we produce called lactase. Lactase production decreases in all humans as we age, but in Crohn's patients this enzyme might be harder to make than normal because it is primarily a product of the ileum. Since Crohn's patients most often have inflammation in the ileum, it would make sense that Crohn's patients might be particularly susceptible to lactose intolerance.
It is easy to test if you have lactose intolerance. Simply drink a glass of whole milk on an empty stomach. Gas production in the belly is the first thing you'll notice - that is the result of bacteria digesting the lactose rather than your own lactase enzyme. Doctors test this in the office by measuring how much hydrogen you breathe out when you have had a glass of millk. After the gas comes the nausea and perhaps vomiting and diarrhea, all typical responses to undigested lactose.
A sensitivity to the casein in milk is probably harder to determine and might require allergy type testing. As someone else posted, there is some evidence that of the casein in cow's milk, which comes in two types (A & B), the type A is responsible for most people's sensitivities. In the US you cannot find out which type you're drinking, but in New Zealand and Australia, for example, dairy farmers have started advertising which kind of casein they're milking. Goat's milk might be the solution to this problem, as I think goats only produce the B-type of casein.
I learned all this by reading on the web, and I'm no expert. But my first symptom of inflammatory bowel disease was the sudden onset of lactose intolerance during my first pregnancy. I started passing blood in my stool right after my baby was born.