Cholesterol metabolism and non-cholesterol sterols in patients with ileal pouch anastomosis

Background: Previous studies suggest only minor changes in bile acid metabolism after panproctocolectomy with ileal pouch construction. Aims/Methods: To investigate these changes further, we studied cholesterol absorption and serum, biliary and fecal non-cholesterol sterols and lipids in 12 ileal pouch patients and 10 controls. Results: In patients, cholesterol absorption was markedly reduced and was associated with low serum total and LDL cholesterol and LDL triglyceride levels, but surprisingly, cholesterol synthesis, as indicated by sterol-balance data or serum cholesterol precursor levels, was within low normal limits. The high proportions of serum plant sterol to cholesterol, particularly that of campesterol, were not related to cholesterol absorption, but were attributable to a markedly reduced biliary cholesterol secretion. Interestingly, in these patients the fractional absorption of campesterol was normal, whereas that of sitosterol, like cholesterol, was reduced and was positively related to the intestinal influx of cholesterol. The patientsʹ serum cholestanol proportion was normal, but the proportion of the cholestanol formed during intestinal passage was significantly reduced (17.9% vs 65.2% in controls). Conclusions: Thus ileal pouch patients are characterized by sterol malabsorption, lowered serum total and LDL-cholesterol levels, but unexpectedly without any increase in cholesterol synthesis. The lack of high serum cholestanol, shown earlier frequently in unoperated patients with ulcerative colitis, may indicate reversible cholestasis, a finding deserving further exploration.