Intestinal Synthesis of Biotin in the Rat Effect of Deficiencies of Certain B Vitamins and of Sulfasuxadine and Terramycin

Biotin uptake by human colonic epithelial NCM460 cells: a carrier-mediated process shared with pantothenic acid

“…The normal microflora of the large intestine synthesizes biotin (6,7,12,41), and human, rat, and minipig colon are capable of absorbing significant amounts of luminally introduced biotin (1,4,33). The mechanism of biotin absorption in the large intestine and the intracellular regulation of that process, however, are not known.…”

“…Absorption of free biotin then takes place mainly in the proximal part of the small intestine via a specialized Na ϩ -dependent, carrier-mediated system (5,21,23,26,(28)(29)(30)(31). As to the second source of biotin, previous studies have shown that a substantial portion of the biotin synthesized by the normal microflora of the large intestine is in the form of free unbound biotin, i.e., available for absorption (6,7,12,41). Furthermore, in vivo studies in humans, rats, and minipigs have shown that the colon is capable of absorbing significant amounts of luminally introduced biotin (1,4,33).…”

Requirements for biotin are not affected by the combination of copper deficiency and fructose feeding.

“…When starch replaces sucrose, there is increased biotin synthesis in the intestinal tract [5,7]. We speculate that fructose is similar to sucrose in the lack of stimulus of microbial biotin synthesis and therefore dietary fructose could increase the biotin supple ment requirement.…”

“…Additionally, it has been reported that a marked change in intestinal flora, both in type and number, takes place when the carbohydrate component of the diet is changed from sucrose to cornstarch [5,7]. When starch replaces sucrose, there is increased biotin synthesis in the intestinal tract [5,7].…”

“…Two groups have reported that the type of dietary carbohydrate [5,6] can cause a substantial change in biotin excretion. In addition, the intestinal synthesis of biotin was increased in rats when the sucrose in their diet was partially replaced by raw potato starch [6].…”