1-Kestose Supplementation Increases Levels of a 5α-Reductase Gene, a Key Isoallolithocholic Acid Biosynthetic Gene, in the Intestinal Microbiota.

1-Kestose (kestose) is the smallest fructooligosaccharide component and shows a particularly high prebiotic function. Both kestose and the bile acid metabolite isoallolithocholic acid (isoalloLCA) are known to be beneficial for human health, especially in terms of immune homeostasis in the gastrointestinal system; however, the effect of kestose on the levels of microbial isoalloLCA producers remains to be clarified. IsoalloLCA is known to be produced by several members of the phylum Bacteroidota that carry the 5α-reductase (5AR) gene, a key isoalloLCA biosynthetic gene. Thus, we designed a specific primer set to detect the 5AR gene based on the consensus sequences of the genes from several isoalloLCA producers. Using real-time quantitative PCR with this primer set and fecal DNA samples, we compared the 5AR gene level (5ar-level) in the intestinal microbiota of a kestose-supplemented group (n=20) and a placebo group (n=16) before and after intake for 12 wk. The 5ar-level was significantly increased in the kestose-supplemented group (p=0.015), but not in the placebo group (p=0.379), indicating that kestose supplementation increased the 5ar-level in human intestinal microbiota. Our findings suggest that targeting functional gene levels could potentially be used to predict and understand the beneficial prebiotic effects associated with changes in gut microbiota.

Hepatic portal venous gas following colonoscopy in a patient with Crohn's disease.

Hepatic portal venous gas is a rare condition that occurs when intraluminal gas or gas produced by intestinal bacteria enters the portal venous circulation. It has recently been recognized as a rare complication of colon procedures by endoscopy or barium enema. Given the frequency of these procedures in patients with inflammatory bowel disease, hepatic portal venous gas may occur more frequently in these patients than previously reported. Here, we report a woman with Crohn's disease who developed hepatic portal venous gas following colonoscopy who was treated with conservative therapy.