Editing Choline (section)

=== Absorption ===
In humans, choline is absorbed from the [[intestine]]s via the [[SLC44A1]] (CTL1) [[membrane protein]] via [[facilitated diffusion]] governed by the choline concentration gradient and the electrical potential across the [[enterocyte]] membranes. SLC44A1 has limited ability to transport choline: at high concentrations part of it is left unabsorbed. Absorbed choline leaves the enterocytes via the [[portal vein]], passes the liver and enters [[systemic circulation]]. [[Gut microbe]]s degrade the unabsorbed choline to trimethylamine, which is oxidized in the liver to [[trimethylamine N-oxide|trimethylamine ''N''-oxide]].<ref name=eu/>

Phosphocholine and [[glycerophosphocholine]]s are hydrolyzed via [[phospholipase]]s to choline, which enters the portal vein. Due to their water solubility, some of them escape unchanged to the portal vein. Fat-soluble choline-containing compounds (phosphatidylcholines and [[sphingomyelin]]s) are either hydrolyzed by phospholipases or enter the [[lymph]] incorporated into [[chylomicron]]s.<ref name=eu/>