Milk
Milk contains a chemical called lactose. Babies make an enzyme called lactase inside their bodies. Adults make less lactase. If they do not have enough, they may not be able to digest lactose anymore. This problem is called lactose intolerance and it affects many adults. There are many medicines that help adults digest lactose. Many lactose-intolerant people drink soy milk instead of animal milk, because it does not contain lactose. Soy milk tastes similar to animal milk, but it is chemically very different and is made from soybeans.