The structure of the small intestine is specialised for rapid absorption of small soluble food molecules.

The apparatus used to model absorption in the small intestine can be set up like this. At regular intervals the liquid inside and outside of the Visking tubing is sampled and tested for starch ...

A few studies have shown a correlation between glucose and the colon’s microbiome, and animal studies have found that lipid absorption is manipulated by the small-intestine microbiota.