Short-chain fructo-oligosaccharide administration dose-dependently increases fecal bifidobacteria in healthy humans

Short-chain fructo-oligosaccharides (SC-FOS) are a mixture of oligosacchari des consisting of glucose linked to fructose units (Gf(n); n = less than or equal to 4), which are not digested in the human small intestine but are f ermented in the colon where they specifically promote the growth of bifidob acteria. In healthy volunteers, we assessed the tolerance and the threshold dose of SC-FOS that significantly increased fecal bifidobacteria counts an d the possibility of a dose-response relationship. Randomly divided into fi ve groups and eating their usual diets, healthy volunteers (40: 18 males, 2 2 females) ingested in two oral doses for 7 d a powder mixture containing ( g SC-FOS/d): 0, G(0); 2.5, G(2.5); 5, G(5); 10, G(10); 20, G(20). Stools we re collected before (d1) and at the end (d8) of sugar consumption, and tole rance was evaluated using a daily chart. Total anaerobe counts were not aff ected by SC-FOS ingestion. Bifidobacteria counts at d8 were greater in grou ps G(10) and G(20) than in G(0) and G(2.5) (P < 0.05). Fecal pH did not dif fer among groups. A significant correlation between the dose of SC-FOS inge sted and the fecal bifidobacteria counts was observed at d8 (r = 0.53; P < 0.01). Excess flatus was significantly more frequent in subjects consuming G(20) than in those consuming G(0,) G(2.5) or G(5) (P < 0.05), and more int ense in G(20) than in G(0) and G(5) groups (P < 0.05). In conclusion, the o ptimal and well-tolerated dose of SC-FOS that significantly increased fecal bifidobacteria in healthy volunteers consuming their usual diet is 10 g/d.