April 8/Health & Medicine Week -- According to recent research from Scotland, "Prebiotics are food ingredients that improve health by modulating the colonic microbiota. The bifidogenic effect of the prebiotic inulin is well established; however, it remains unclear which species of Bifidobacterium are stimulated in vivo and whether bacterial groups other than lactic acid bacteria are affected by inulin consumption."

"Changes in the fecal microbiota composition were examined by real-time PCR in 12 human volunteers after ingestion of inulin (10g/d) for a 16-day period in comparison with a control period without ally supplement intake. The prevalence of most bacterial groups examined did not change after inulin intake, although the low G + C % Gram-positive species Faecali-bacterium prausnitzii exhibited a significant increase (10.3 % for control period v. 14.5 % during inulin intake, P=0.019). The composition of the genus Bifidobacterium was studied in four of the volunteers by clone library analysis. Between three and five Bifidobacterium spp. were found in each volunteer. Bifidobacterium adolescentis and Bifidobacterium longum were present in all volunteers, and Bifidobacterium pseudocatenulatum, Bifidobacterium animalis, Bifidobacterium bifidium and Bifidobacterium dentitum were also detected," wrote C. Ramirezfarias and colleagues.

The researchers concluded, "Real-time PCR was employed to quantify the four most prevalent Bifidobacterium spp., B. adolescentis, B. longum, B. pseudocatenulatum and B. bifidum, in 10 volunteers carrying detectable levels of bifidobacteria. B. adolescentis showed the strongest response to inulin consumption, increasing from 0.89 to 3.9% of the total microbiota (P=0.001). B. bifidum was increased from 0.22 to 0.63% (P <0.001) for the five volunteers for whom this species was present."

Ramirezfarias and colleagues published their study in British Journal of Nutrition ("Effect of Inulin on the Human Gut Microbiota: Stimulation of Bifidobacterium Adolescentis and Faecalibacterium Prausnitzii." British Journal of Nutrition, 2009;101(4):541-550).

For additional information, contact P. Louis, Rowett Research Institute, Gut Health Division, Microbial Ecology Group, Greenburn Rd., Bucksburn AB21 9SB, Aberdeen, Scotland.

From the April 13, 2009, Prepared Foods E-dition