Lactose and Casein

I often get email similar to the following, so it's time to remind people of some basic definitions.

Could you please let me know what difference (if any) there is between casein and lactose intolerance. I'm confused.

Here was my answer:

They are two totally different things.

There's no such problem as casein intolerance, although you may sometimes see the term. Casein is a protein is milk, actually a whole family of similar proteins. The other protein family in milk is whey.

Proteins can sometimes enter the bloodstream where the immune system thinks they are invaders and attacks them. This is called an allergic response. Cow's milk protein allergy is the overall term for several types of dairy allergies, which can be to the casein or to the whey or both.

Some people do get gastrointestinal problems as allergy symptoms, but hives, rashes, respiratory complaints, and a host of other symptoms are more common.

Lactose is the sugar in milk. All people can manufacture lactase, the enzyme that digests lactose, at least until they're weaned. Many adults can as well. But if you don't manufacture enough lactase the undigested lactose can cause symptoms including diarrhea, gas, bloating, and cramps. This is called lactose intolerance.

There's really nothing you can do for a dairy allergy except avoid dairy products.

You can take lactase pills to digest the lactose, however, and these should work as well as having natural lactase.