Long-term supplementation of isomalto-oligosaccharides improved colonic microflora profile, bowel function, and blood cholesterol levels in constipated elderly people—A placebo-controlled, diet-controlled trial

Abstract Objectives The main purpose of this study was to determine the long-term (8 wk) effects of isomalto-oligosaccharide (IO) supplementation on fecal microflora, bowel function, and biochemical indicators of nutritional status in constipated elderly subjects. We also assessed whether the effect of IO was sustained after its withdrawal. Methods Thirteen (five male) constipated subjects (age 82.5 ± 1.9 y) participated in this diet-controlled study that consisted of a 4-wk placebo period, two 4-wk IO (10 g/d) -supplementation periods (IO1 and IO2), and a 4-wk post period. Fasting blood was collected on the last day of each period. Stools were collected during the last week of each period. The bowel function was monitored throughout the study. Results The fecal bifidobacteria, lactobacilli, and bacteroides counts (log counts/g wet feces) significantly increased and clostridia count decreased at the end of the IO1 period. The effects were more pronounced in the IO2 period and then returned to the levels of the IO1 period at the end of the post period. Daily fecal excretion of acetate and propionate increased along with IO supplementation. The frequency of spontaneous defecation increased in the IO2 period, and wet fecal mass increased by 24% in both the IO1 and the IO2 periods. The effects of IO on bowel function diminished in the post period. Plasma total and low-density lipoprotein cholesterol levels were lower with 4- or 8-wk IO supplementation as compared with the placebo and post period, respectively. Conclusions IO supplementation into a low-fiber diet improved colonic microflora profile and bowel movement in a time-dependent fashion in constipated elderly subjects. These beneficial effects decreased after discontinuation of the supplements.