In a message dated 97-09-13 17:30:59 EDT, Dave writes:
> Could someone please explain why adults who were
>  apparently lactose tolerant all their lives suddenly
>  become intolerant, especially in their thirties.

Lactose intolerance results from insufficient levels of the enzyme
lactase in the small intestine.  It is normally present in large
quantities at birth, but enzyme production drops after the age of
two and, in most people, continues to drop into adulthood. You
most likely just hit the point where the lactose intolerance became
noticeable.   Since it came on so suddenly, I would theorize that
it began with a stomach  flu or spoiled food episode that wiped out
the existing lactase stores, and you just no longer have the ability
to rebuild them.  Since you continued to have diarrhea for months,
that would have interfered with any minimal rebuilding of the lactase
stores that you were capable of.  You would have reached this
point anyway; you just reached it more abruptly than usual.

The books I have read indicate that lactose intolerance is the
norm, and the ability to digest milk in adulthood is a mutation
most commonly found in people of western European descent.
If you have Asian, African, Mediterranean, or Jewish
ancestry, you are more likely to be lactose intolerant, and
it is more likely to show up earlier.  Interestingly, of the
western-European Americans with lactose intolerance that
I know, all became intolerant in their  thirties.  However, I
have lactose intolerant Asian and Jewish friends who have
been this way since late childhood.

A coping strategy that I recommend to everyone: try vegan
eating when you go out -- look for a good vegetarian restaurant,
and ask for it ("vee'-gn"). Indian, Thai, and Chinese foods
are also good sources of non-dairy food (just watch for yogurt
and butter, depending on what you order).

Cheers,

K