FOS Consumption Yields Mixed Results

WAGENINGEN, Netherlands--Intake of fructooligosaccharides (FOS), a prebiotic, increased beneficial bacteria but caused intestinal complaints in humans, according to a study published in the Journal of Nutrition (136, 1:70-74, 2006).

Researchers from the Wageningen Center for Food Sciences conducted a double blind, placebo-controlled, crossover study of 2 x 2 weeks, with a washout period of two weeks, on 34 healthy men. Each day, subjects were given lemonade containing either 20 g FOS or placebo, as well as the intestinal permeability marker chromium EDTA (CrEDTA). On the last two days of each active treatment period, subjects scored their gastrointestinal complaints and their intestinal output was measured for 24 hours. According to the results, FOS consumption increased fecal weight and intestinal lactic acid, and raised levels of beneficial bifidobacteria and lactobacilli. However, FOS intake also increased flatulence and intestinal bloating, and doubled fecal mucin excretion, indicating mucosal irritation. The researchers concluded the FOS-induced increase in mucin excretion suggests mucosal irritation in humans, but the overall effects are more moderate than those in rats.