Ask Peggy

Are milk allergies common?

Dear Peggy: I've heard so much about food allergies. Are milk allergies common? —A.W., Middleton, Wisconsin

They're not as common as you might believe. Many people who think they have a milk allergy are actually lactose-intolerant. With a milk allergy, the body can't handle casein and other protein components in milk. The immune system starts working, causing a reaction.

With lactose intolerance, the body can't easily digest the sugar, or lactose, in milk. The body doesn't produce enough lactase, the enzyme that digests lactose. This results in varying degrees of digestive discomfort.