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Lactose intolerance
Make it clearer
Lactose is the sugar in milk. Lactose intolerance is the set of digestive complaints that show up after eating something that contains it: bloating, abdominal pain, gas, nausea and diarrhea.
The problem lies with an enzyme. Lactase sits in the brush border of the small intestine, the surface covered with microscopic hairs where food is absorbed, and its job is to split lactose into two smaller sugars, glucose and galactose. When lactase falls short, lactose stays whole in the intestinal lumen, that is, in the open space the food travels through.
And two things happen there. The bacteria that live in that stretch have a feast: they ferment the lactose and give off hydrogen, methane and carbon dioxide. And the unabsorbed lactose raises the osmotic pressure inside the intestine, the force with which dissolved material pulls water, and draws fluid in. Lactose that was never split acts like a sponge: it holds water inside the intestine.
In brief
Lactose intolerance is the set of digestive symptoms that follows eating foods with lactose: bloating, abdominal pain, gas, nausea and diarrhea.
Lactase in the brush border of the small intestine splits lactose into glucose and galactose; when lactase falls short, undigested lactose stays in the intestinal lumen.
There, bacteria ferment it and release hydrogen, methane and carbon dioxide, and the unabsorbed lactose raises osmotic pressure and pulls in fluid.
Lactose that was never split acts like a sponge: it holds water inside the intestine.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingLactose Intolerance, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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