if you’re lactose intolerant, why does the lactose cause bowel distress instead of passing through inertly?

Question

I get that lactase is needed to break it down into galactose and glucose, but why does the two monosaccharides’ glycocidic linkage cause so much pain and problems during digestion if it’s isn’t broken apart?

In: 104

Answer 1

Lots of common bacteria can make lactase. If you don’t break up and absorb the lactose before it reaches the bacteria in your large intestine, they’ll consume it for energy and produce carbon dioxide gas in the process. Fermenting a little lactose makes a big volume of carbon dioxide, which pushes on your guts in painful and inconvenient ways.