A daily dose of four grams of xylooligosaccharides (XOS) for three weeks increased populations of bifidobacteria to similar levels as could be achieved with double the dose of fructo-oligosaccharides, one of the established prebiotics, wrote the authors in the journal Nutrition Research. "These results suggest that XOS was more efficient than FOS and inulin in promoting the growth of bifidobacteria," wrote lead author Yun-Chin Chung from the Providence University. Prebiotic ingredients, or those that boost the growth of beneficial probiotic bacteria in the gut, are worth about €90 million in the European marketplace but are forecast to reach €179.7 million by 2010, according to Frost & Sullivan. The market has been largely created by three inulin producers, all based in Europe, but other ingredient manufacturers are increasingly looking to promote the prebiotic effect of their products as evidence suggests that prebiotics could be even more useful than the probiotic bacteria that they feed.
Chung and co-workers recruited 22 elderly subjects with an average age of 78.6 and randomly assigned 13 to receive a daily supplement of XOS (provided by Suntory Co, Japan), and nine to receive placebo (sucrose). All subjects were free of gastrointestinal disease. At the end of the study, the population of bifidobacteria in the XOS supplementation group increased by a significant 35 per cent (2.2 log10 colony forming units (CFU) per gram of faeces), while no significant increases were observed in the placebo group. This increase is reported to be achieved at a much lower dose that is necessary for inulin and fructooligosaccharides - reports in the literature state that the effective daily dosage of oligosaccharide for humans is 3.0 g for FOS and 0.7 g for XOS (Food Tech, 1994, Vol. 48, pp. 61-65). Moroever, the moisture content in the XOS supplemented group improved, and the faecal pH decreased. The lowering of pH came as a result of an increased production of short chain fatty acids (SCFA) like butyrate and proprionate, which can contribute towards an improved intestinal health and consequently a reduced risk of digestive disorders.
In contrast to inulin and fructooligosaccharides, the researchers did not report any changes in mineral levels - the more established prebiotics promote calcium and phosphorus absorption in the intestine, with obvious benefits for bone health. No adverse effects were reported by the authors for XOS. "In conclusion, our results indicate that XOS supplementation at 4 g/d for 3 weeks did not adversely influence GI symptoms, haematologic and biochemical parameters, and nutrient intakes in elderly subjects," wrote the researchers. "Furthermore, the supplement of XOS significantly increased the faecal moisture content and the population of bifidobacteria, and decreased the faecal pH value. Therefore, XOS-containing diets may be beneficial to GI health in the elderly."
Prebiotics, which are derived from insoluble fibres and oligosaccharides, can be incorporated into a wider variety of end products than probiotic bacteria. They have also benefited from the promotional efforts of probiotic suppliers, who have significantly raised public awareness of gut health in recent years. The study was supported by the National Science Council, Taiwan. Source: Nutrition Research (Elsevier) Volume 27, Pages 756-761 "Dietary intake of xylooligosaccharides improves the intestinal microbiota, fecal moisture, and pH value in the elderly"
Authors: Y.-C. Chung, C.-K. Hsu, C.-Y. Ko, Y.-C. Chan