Beneficial effects of fructo-oligosaccharides supplementation on fecal bifidobacteria and index of peroxidation status in constipated nursing-home residents--a placebo-controlled, diet-controlled trial.

OBJECTIVE: This study assessed effects of fructo-oligosaccharides (FOS) supplementation on fecal bifidobacteria, lipid peroxidation index, indices of nutritional status, and whether effects of FOS were sustained after its withdrawal in constipated nursing-home residents. The associations of fecal bifidobacteria and blood measurements were also examined. METHODS: Six men and four women participated in a double-blind, diet-controlled study that consisted of a 4-wk placebo (3 mL of fructose syrup) period, a 4-wk FOS (10 g/d) period, and a 4-wk post-FOS period. Stools were collected during the last week of each period to determine the microflora and fecal weight. Fasting blood was collected at the end of each period and analyzed for thiobarbituric acid-reactive substances (TBARS) and biochemical indices. RESULTS: Fecal counts (log counts/gram of dry feces) and daily fecal output of bifidobacteria significantly increased with FOS compared with placebo. The effect on bifidobacteria output was sustained in the post-FOS period. Plasma TBARS concentration was reduced by 16% and 21% in the FOS and post-FOS periods, respectively, compared with that in the placebo period. The plasma cholesterol level was significantly lowered by 7% in the FOS and post-FOS periods compared with that in the placebo period. The increases in fecal bifidobacteria output during the FOS period (log colony-forming units per day) were associated with decreases in plasma TBARS and plasma cholesterol, respectively. CONCLUSION: Supplementation of FOS increases the daily output of bifidobacteria and decreases plasma TBARS and cholesterol concentrations in constipated nursing-home elderly residents and these effects remained at the end the post-FOS period.