Review
Version 1
This version is not peer-reviewed
Can Vitamin D Be Supplied from the Large Intestine?
Version 1
: Received: 3 October 2024 / Approved: 4 October 2024 / Online: 4 October 2024 (10:35:13 CEST)
How to cite: Fraser, D. Can Vitamin D Be Supplied from the Large Intestine?. Preprints 2024, 2024100312. https://doi.org/10.20944/preprints202410.0312.v1 Fraser, D. Can Vitamin D Be Supplied from the Large Intestine?. Preprints 2024, 2024100312. https://doi.org/10.20944/preprints202410.0312.v1
Abstract
The discovery that vitamin D2 is being generated by anaerobic microbial metabolism in the alimentary tract, raises the question whether such a source of vitamin D could contribute to vitamin D supply for the animal hosting this microbial production system. In ruminants, this microbial generation in the forestomach allows vitamin D2 to be readily absorbed when it reaches the small intestine, contributing to vitamin D2 and 25-hydroxyvitamin D2 [25(OH)D2] found in their tissues. In monogastric animals like humans, the microbial generation of vitamin D2 is occurring in the large intestine. There is evidence that vitamin D hydroxy metabolites, delivered to the lumen of the colon can be absorbed. However, the parent vitamin D is more lipophilic than its metabolites, and like lipophilic vitamin K2 being produced by bacteria in the hindgut, may be poorly absorbed by the colon mucosa. It is now apparent that colon mucosal cells have the proteins megalin and cubilin in their basal membrane. These glycoproteins perform endocytosis of circulating proteins including vitamin D binding protein [DBP]. Inside the cell, DBP binds to cytoplasmic actin and thus provides an array of high affinity binding sites for vitamin D and its functional metabolites. Any traces of vitamin D2 that may diffuse into the colon mucosal cells from the lumen would thus be retained and accumulate on the DBP-actin. It would then be a substrate for functional hydroxylase metabolism for local endocrine action in these cells, and subsequent delivery of 25(OH)D2 by diffusion to apo-DBP in the circulation.
Keywords
Vitamin D2; Microbial metabolism; Colon mucosa; Megalin and cubilin; Vitamin D-binding protein
Subject
Medicine and Pharmacology, Dietetics and Nutrition
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Comments (0)
We encourage comments and feedback from a broad range of readers. See criteria for comments and our Diversity statement.
Leave a public commentSend a private comment to the author(s)
* All users must log in before leaving a comment
