What are you allergic to?

[Furiously]

Now:
Horses.  (Well - have not tested in the past few years. Needless to say - very allergic)

As a kid:
Peanut Butter
Cats
Dust
Grass
Smoke

The Lactose thing Rasix and a few others mention is interesting. As near as I can tell, I'm not allergic to milk, but if I have a lot of dairy without a lactose pill 20 minutes later I'll be sitting on the toilet. There are other foods that occasionally give the same reaction, but the lactose pill seems to keep it all in check. It was horrid before I figured out the whole thing, I'd wake up at 3:00 with my intestines cramping up. (I think a round of anti-biotics killed off some of my digestive enzimes. Why you can't take a pill to get them back is what I would like to know.)

[voodoolily]

It's not the enzymes that are killed by antibiotics, it's the beneficial bacteria in your gut. They help break down the stuff that the digestive enzymes in your gut can't handle. In fact, gas is caused by the respiration of those little critters. You can get them back by taking acidophilus cultures, which can be found in yogurt (make sure you get the kind with live cultures, like Nancy's) or by buying straight-up acidophilus at the health food store.

People who can't digest lactose are missing the lactase enzymes in their gut. That's what the lactose pill is made of. It breaks lactose down into glucose and galactose, if my cell biology serves me correct. Both glucose and galactose are simple sugars that the body can process more easily.

(Wiki check: sweet! All those cell bio classes paid off. I remembered right.)

[Strazos]

Then what about people who are merely sensitive to lactose? Do they just have a shortfall of enzymes then?

[voodoolily]

Well, truth be told, milk is for babies. Humans are the only mammals that drink it past infancy (not counting when we feed it to our pets). I have no lactose sensitivity issues per se, but if I chug a glass of milk I get mucousy. And cheese kinda bloats me up (but it is SO worth it!). So I don't really know if people who are sensitive to dairy products just have a lesser concentration of lactase in their digestive tract or are sensitive to the milkfat. A high-fat diet can also be responsible for diarrhea, so I could easily see how a reaction to dairy might be construed as a lactose issue. Also, from what I've heard from friends with issues, goat and sheep's milk don't have the same effects as cow's milk, even though they're all rumenants (have four stomachs).