Effects of oligosaccharide on the faecal flora and non-specific immune system in elderly people

Aims: The primary objectives was to confirm the bifidogenic effects of fructooligosaccharides in elderly subjects (increase equal or higher than I log endogenous bifidobacteria per gram of faeces), and to make an exploratory investigation on non-specific immune defense parameters, such as phagocytosis and changes in lymphocyte subpopulations, in relation to the increase in endogenous bifidobacteria. Methods: The study was a pretest/posttest study of 19 elderly nursing home patients, with one period of 3 weeks of 8 g fructooligosaccharides (FOS) given in portions of 4 g, twice a day. Faecal bacteria composition was investigated using, viable counts, lymphocyte subpopulation was analysed using a FACS scan, and relative expression of interleukin-6 (IL-6) by measuring levels of IL-6 mRNA in peripheral blood monocytes. Results: Bacterial counts for bifidobacteria increased by a mean of 2.8 +/- 0.57 log(10)CFU/g faeces after 3 weeks of supplementation, and decreased by a mean of 1.1 log(10)CFU/g faeces after the period without FOS (post-test). Unexpected changes in non-specific immunity were observed: decreased phagocytic activity of granulocytes and monocytes, as well as a decreased expression of interleukin-6 mRNA in peripheral blood monocytes. These results suggest a possible decrease in inflammatory process in elderly subjects after FOS supplementation. Conclusion: The results confirm the bifidogenic effect of FOS with a 2 log increase in bifidobacteria counts and the frail elderly subjects showed low counts at the beginning of study. A diminution in inflammatory process is suggested by the decreased expression of IL-6 mRNA in peripheral blood monocytes. These results need confirmation in further studies. (C) 2002 Elsevier Science Inc. All rights reserved.