FGF19 and glycogen storage disease VI: FGF-19 is produced by enterocytes in the distal ileum on uptake of bile acids,[37] and a correlation with bile acid malabsorption in Crohn’s disease has recently been shown.[38] The observed decrease in serum FGF-19 was most pronounced in patients with ileal involvement, probably reflecting that 77% of the patients with ileal/ileocolonic disease had undergone surgical resection.