ORIGINAL ARTICLE Suppressive effect of partially hydrolyzed guar gum on transitory diarrhea induced by ingestion of maltitol and lactitol in healthy humans S Nakamura 1,2 , R Hongo 1 , K Moji 2 and T Oku 1 1 Graduate School of Human Health Science, Siebold University of Nagasaki, Nagasaki, Japan and 2 Research Center for Tropical Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan Objectives: To estimate the suppressive effect of partially hydrolyzed guar gum (PHGG) on transitory diarrhea induced by ingestion of a sufficient amount of maltitol or lactitol in female subjects. Design: The first, the minimal dose level of maltitol and lactitol that would induce transitory diarrhea was estimated separately for each subject. Individual subject was administered a dose that increased by 5 g stepwise from 10 to 45 g until diarrhea was experienced. Thereafter, the suppressive effect on diarrhea was observed after each subject ingested a mixture of 5 g of PHGG and the minimal dose level of maltitol or lactitol. Setting: Laboratory of Public Health Nutrition, Department of Nutrition and Health Sciences, Siebold University of Nagasaki. Subjects: Thirty-four normal female subjects (21.370.9 years; 49.575.3 kg). Main outcome measurement: Incidence of diarrhea caused by the ingestion of maltitol or lactitol and the ratio of suppression achieved by adding PHGG for diarrhea. Results: The ingestion of amounts up to 45 g of maltitol, diarrhea caused in 29 of 34 subjects (85.3%), whereas the ingestion of lactitol caused diarrhea in 100%. The diarrhea owing to maltitol was improved in 10 of 28 subjects by the addition of 5 g of PHGG to minimal dose-induced diarrhea, and that owing to lactitol was in seven of 19 subjects. Adding 10 g of PHGG strongly suppressed the diarrhea caused by maltitol, and the cumulative ratio was 82.1% (23/28). Conclusion: The transitory diarrhea caused by the ingestion of maltitol or lactitol was clearly suppressed by the addition of PHGG. These results strongly suggest that diarrhea caused by the ingestion of a sufficient amount of non-digestible sugar substitute can be suppressed by the addition of dietary fiber. European Journal of Clinical Nutrition (2007) 61, 1086–1093; doi:10.1038/sj.ejcn.1602623; published online 24 January 2007 Keywords: transitory diarrhea; suppressive effect; maltitol; lactitol; partially hydrolyzed guar gum Introduction Sugar alcohols including maltitol and lactitol have been widely used and marketed as bulking sucrose substitutes with beneficial effects on both human health and on the improvement of food quality (Oku, 2005). Maltitol is a typical non-digestible sugar substitute with good sweetness (Oku et al., 1991; Oku, 1996a, b, 2005). The metabolic pathway in the human gastrointestinal tract of non- digestible sugar substitutes is as follows: they escape diges- tion and absorption in the small intestine, and supply energy to the host via fermentation by microbes in the large intestine (Tokunaga et al., 1989; Noda and Oku, 1992). The main products of the microbes’ fermentation are short chain fatty acids, such as acetate, propionate, and n-butyrate, hydrogen, methane and carbon dioxide (Wursch et al., 1989; Reaugerie et al., 1990; Cummings and Macfarlane, 1991; Natah et al., 1997; Oku and Nakamura, 2003). Non-digestible sugar substitutes directly or indirectly bring about beneficial health effects during their passage through the gastro- intestinal tract. (Oku and Noda, 1990; Wolfgang et al., 2001; Oku and Nakamura, 2002). However, ingestion of a sufficiently large amount of non- digestible and/or non-absorbable sugar substitutes causes Received 29 June 2006; revised 21 November 2006; accepted 21 November 2006; published online 24 January 2007 Correspondence: Dr T Oku, Graduate School of Human Health Science, Siebold University of Nagasaki, 1-1-1 Manabino, Nagayo, Nagasaki, 8512195, Japan. E-mail: okutsune@sun.ac.jp Guarantor: T Oku. Contributors: The study was designed by TO. SN, RH and KM conducted the experiment, and TO and SN were responsible for data analysis, interpretation of data, and the contents of this paper. European Journal of Clinical Nutrition (2007) 61, 1086–1093 & 2007 Nature Publishing Group All rights reserved 0954-3007/07 $30.00 www.nature.com/ejcn