Lactase is the enzyme that digests lactose. Virtually all humans
make lactase at birth so that they can digest the lactose in
breastmilk. Starting at about three, the age of normal weaning,
humans, like almost every other mammal, naturally stop producing
lactase. It's just not needed. Not having lactase results in
lactose intolerance, the name for having symptoms when you drink
or eat any dairy product that contains lactose, which is most of
them. Wouldn't it be great if scientists could figure out a way
to artificially manufacture lactase? Back in the 1970s, a Dutch
company named Gist-Brocades did exactly that. Along the way they
discovered something fascinating and important. It all has to do
with digestion. The human stomach is highly acidic. Hydrochloric
acid is produced to help digest and break down food. Stomach
acid could burn holes in your shirt if it leaked out. Lactase is
made in the small intestine, under conditions that are far less
acidic. In fact, if you swallow lactase it won't work. The
stomac