Publications

PURPOSE OF REVIEW: The colon is an effective bioreactor with auxotrophic microbiota that can serve by hydrolyzing dietary and endogenous protein, as well  as by synthesizing essential amino acids through nitrogen salvage. Due to assumed  negligible amino acid absorption, this colonic contribution was thought to be  minimal, but this may not be true. RECENT FINDINGS: Several studies that examined  the colonic environment in health and disease, show the presence of proteases in  the colonic lumen, which are of both host and microbial origin, along with  indirect evidence of amino acid transporters in the colonic epithelium. There are  also amino acid biosynthetic pathways in the microflora, and the contribution of  colonic amino acid to host amino acid nutrition has been shown in wild animals.  Yet, current direct and quantitative evidence on amino acid absorption in human  colon is minimal. SUMMARY: Although amino acid absorption in colon is not very  well established, current studies show that substantial amounts of amino acid  could possibly be contributed to the host by the colon. There is a need for  assessing this contribution quantitatively using direct isotopic methods under  different nutritional conditions, dietary intakes, and clinical conditions.