Fat digestion after jejunoileal bypass operation for obesity.

Fat digestion in the upper jejunum was studied in 12 obese patients treated by jejunoileal bypass including either 37.5 cm jejunum and 12.5 cm ileum or 12.5 cm jejunum and 37.5 cm ileum. Jejunum was intubated and a test meal ingested before and 1-2 months after operation. Jejunal aspirates were heated immediately to destroy lipase, pooled and assayed for dilution marker, bile acids and total fat. Lipolytic products were determined by thin-layer chromatography and densitometry. The micellar phase was achieved by ultracentrifugation and analysed for total fat. Results. Bile acid concentration and lipolysis decreased after both bypass operations. In accordance with this, micellar solubilization of fat was impaired after operation. Bile acid concentration and micellar solubilization were lower after bypass with a long, than after bypass with a short, ileal loop. Absorption of fat in the duodenum and upper jejunum did not change significantly after any of the operations. Conclusions. Jejunoileal bypass impairs fat digestion, but this does nto contribute significantly to the fat malabsorption after operation.