Studies on Thiamine Absorption

Abstract

Summary

Thiamine absorption from intestinal tract of chicks was studied using ligated loops or analyzing tract contents for C¹⁴ and thiamine in chicks fed thiamine-2-C¹⁴. In one hour about 84% of a 250 μg dose of thiamine was absorbed from chick duodenal loops, but only barely detectable amounts of 7 to 15% from ceca and upper and middle sections of remaining small intestine. No absorption occurred at this dose from crop or lower small intestine. A thiamine dose-absorption curve for duodenum was linear up to doses of 10 mg. Proportionately less thiamine was absorbed from middle small intestine as doses increased in ligated loops from 6.25 to 100 μg; yet in duodenum almost 90% of the 100 μg dose was absorbed. Chicks fed 5.8 or 10.6 ppm thiamine in stock rations had a similar profile in intestinal tract concentrations with lowest value in middle ⅓ of small intestine. Chicks fed 127 ppm thiamine had progressively increasing thiamine concentrations in sections of small intestine distal to duodenum. The data indicate that thiamine is absorbed primarily in the upper small intestine and when fed at very high levels to chicks is secreted by intestinal mucosa of middle and lower sections of small intestine.