Why do some people have an intolerance to lactose?
Why do some people have an intolerance to lactose?
user
Oh yes, this is an intolerance to one of the components of dairy.  Do you want me to explain why?  Do you want more information?
assistant
Yes, I would like to know why some get it but others don't.
user
Alright.  There are enzymes that help to break down lactose in the intestine.  If one or more of these enzymes are not functioning, then more lactose will be transported across the intestine wall than the body is able to use, and so some is excreted in the stool.  In some people, this will happen more often, and that's what we call an intolerance.
assistant
Is lactose intolerance present from birth or can people develop it over time?
user
It can present at any age.  Some people are born with lactose intolerance, while other develop it later in life.
assistant
What causes lactose intolerance to develop?
user