People who are lactose-intolerant

a. are allergic to dairy.
b. cannot break down the lactose found in milk.
c. can never eat anything that's made with a dairy ingredient.
d. cannot handle the protein, fats, minerals, and vitamins in milk.

cannot break down the lactose found in milk. Lactose is

a disaccharide composed of glucose and galactose. It is found in milk

in 2-8%. Lactose-intolerant people cannot break down the lactose into

glucose and galactose. Undigested lactose in the gastrointestinal tract

can cause belly pain, bloating, and gas.