Lactase is an enzyme produced in the intestine that breaks
down milk sugar (lactose). When a person becomes lactase-deficient (also called
lactose-intolerant), he or she has difficulty digesting milk and milk products.
The undigested lactose is used as food by bacteria that are normally found in
the intestine. This can cause diarrhea, a large amount of gas, and
causes some people to become temporarily lactase-deficient. It may take as long
as 1 month to be able to eat milk and milk products again without a
If a person being treated for giardiasis has symptoms
that suggest this is a problem, he or she should avoid milk products for at
least 1 month. Then add them gradually back into the diet as the body can
How this information was developed to help you make better health decisions.