Dietary prebiotics are typically fiber compounds that human beings cannot digest. However, prebiotics can be digested by the friendly probiotic bacteria that reside in our gut, nourishing them, stimulating their growth or activity and helping them to colonize the large intestine.1 In the world of dietary supplements, there are several prebiotics from which to choose—perhaps the best known of which is fructooligosaccharides. Whatever the type, one feature which they all have in common is that several grams (five or more) are typically required in order to provide clinical benefit. There is, however, one exception to this: PreticX branded xylooligosaccharides (XOS), which have been shown to provide prebiotic benefits with just a dose of about 1 g.
What is XOS?
XOS are mainly composed of two or three xylose units with beta-1,4 linkages. They are obtained by hemicellulose hydrolysis, which is relatively abundant in the cell walls of grains. In this article, we will discuss the research conducted on XOS, the beneficial effects as a prebiotic, and for glucose modulation, and improving constipation.
As a Prebiotic
In a double-blind, randomized, placebo-controlled study,2 healthy adult subjects (n = 32) received 1.4 g or 2.8 g XOS (as PreticX from AIDP), or placebo in daily doses. The study consisted of a two-week run-in, an eight-week intervention, and a two-week washout phase. Stool samples were collected at baseline, after four and eight weeks of intervention and two weeks after cessation of intervention. Samples were subjected to culture, pyrosequencing of community DNA, pH and SCFA analyses. Tolerance was evaluated by daily symptom charts. The results were that XOS was tolerated without significant gastrointestinal side effects, and bifidobacterium counts increased in both XOS groups compared to the placebo subjects. The 1.4 g per day group had significantly higher bifdobacterium counts compared to the placebo group subjects at eight and 10 weeks. The researchers concluded that XOS supplementation “may be beneficial to gastrointestinal microbiota” and “The low dose required, and lack of gastrointestinal side effects makes the use of XOS as a food supplement feasible.”
It should be noted that in this XOS study, the minimum effective dose of 1.4 g was based upon a 70 percent XOS material. Therefore, 0.98 g XOS was the yield (i.e. 1.4 X 70 percent = 0.98). However, a 95 percent XOS material is also available, so only 1.032 g would be necessary to yield the same 0.98 g—a very low dose in either case.
In another study,3 three formulations were used: XOS 8 g/d, Bifidobacterium animalis subsp. lactis Bi-07 109 CFU/d, or a combination of 8 g XOS+109 CFU Bi-07/d. These were given to healthy adults (25-65 years) for 21 days. Results were that XOS supplementation increased average bowel movements per d (P= 0·009), significantly increased participant-reported vitality (P= 0·003) and happiness (P= 0·034), and significantly increased fecal bifidobacterial counts (P= 0·008) and fasting plasma HDL concentrations (P= 0·005), and modulated various immune cells (P= 0·027). Use of XOS+Bi-07 together led to the lowest reported use of analgesics (P= 0·004), also significantly increased faecal B. lactis content (P= 0·007) and lowered various inflammatory makers (P= 0·035-0·040).
In a 2015 study,4 prediabetic (Pre-DM) (n = 13) or healthy (n = 16) subjects were randomized to receive 2 g/day XOS or placebo for eight weeks. Results showed that XOS significantly decreased or reversed the increase in abundance of the Howardella, Enterorhabdus and Slackia genera observed in healthy or Pre-DM subjects (which are associated with pre-DM). Likewise, abundance of the species Blautia hydrogenotrophica was lower in pre-DM subjects, which XOS increased its abundance. This is the first clinical observation of modifications of the gut microbiota by XOS in both healthy and Pre-DM subjects in a pilot study. Prebiotic XOS may be beneficial in reversing changes in the gut microbiota during the development of diabetes.
XOS and Glucose Modulation
A few different studies have investigated the effect of XOS on blood glucose levels. In one randomized double-blind study,5 the effect of XOS, 4 g/day, versus placebo, 4 g/d, were evaluated among 26 type 2 diabetic outpatient subjects. The results showed that XOS supplementation reduced the glucose, HbA1c and fructosamine concentrations (makers for long-term glucose control), as well as total cholesterol, low density lipoprotein (LDL) cholesterol, oxidized low density lipoprotein (ox-LDL) and apolipoprotein B. In conclusion, supplementation with XOS for eight weeks was effective in improving blood sugar and lipids in type 2 diabetes, indicating that XOS-containing diets might be beneficial to DM subjects. A follow-up study, using 4 g of PreticX, saw significant reduction in blood glucose, HbA1c and fructosamine after eight weeks.6
A randomized double-blind cross-over study was conducted7 to investigate the effects of a xyloologosaccharide (XOS)-sugar mixture on blood glucose in human subjects. Sucrose with 14 percent XOS powder (XOS14) and sucrose with 20 percent XOS powder (XOS20) was used. Results were that XOS14 and XOS20 showed significantly lower area under the glucose curve (AUC) for 0-15 min (p = 0.0113), 0-30 min (p = 0.0004), 0-45 min (p < 0.0001), 0-60 min (p < 0.0001), 0-90 min (p < 0.0001), and 0-120 min (p = 0.0001). Compared with glucose, the blood glucose levels of XOS14 and XOS20 were significantly lower at every time point between 15 and 120 minutes. In conclusion, XOS14 and XOS20 had an acute suppressive effect on postprandial glucose surge.
Another study8 evaluated the effect of sucrose containing two different levels of XOS on the glycemic index (GI) and blood glucose response in healthy adults (four male and six female, n = 10). Participants were randomized to receive glucose, sucrose, sucrose containing 7 percent XOS active elements (XOX7), or 10 percent XOS active elements (XOS10). Each participant was administrated one of these materials once a week for eight weeks and an oral glucose tolerance test was performed. Results were a reduction in the glycemic response to sucrose that with XOS7 and XOS10, with glycemic indices of 68.9, 54.7, and 52.5, respectively. The GI values of XOS7 and XOS10 were similar to that of foods with low GI. The percentage reduction of GI value caused by sucrose containing XOS was significantly different and dose-dependent as compared to that caused by sucrose alone (p < 0.05). The reduction in the glycemic response to XOS7 and XOS10 was 21 percent and 24 percent, respectively, as compared to the glycemic response to sucrose. These results demonstrated that XOS may be effective in protecting humans against overconsumption of sucrose.
XOS and Constipation
To investigate the effects of the intake of an XOS-sugar mixture on bowel regularity and symptoms in 56 constipated young women (mean age of 22.1 years old), two experiments9 were conducted. In experiment 1, a randomized double-blind study was performed to evaluate the effect of six weeks’ intake of 10 g sucrose containing 7 percent XOS or 10 g sucrose on constipation. In experiment 2, a 24-g coffee mixture containing 12.8 g plant cream and 11.2 g of a xylooligosaccharide-sugar mixture was consumed by the subjects. During the study, the clinical efficacy was assessed by using a daily diary. The subjects indicated daily stool frequencies and clinical symptom scores. Results were that in experiment 1, the mean stool frequency was 2.07 in the pretreatment week and increased significantly to 4.05, 4.42, 4.84, 4.84, and 4.05 in weeks two to six of XOS intake, in comparison with the 3-3.67 with sucrose intake (sucrose, SUC). In experiment 2, mean stool frequency significantly increased from 2.47 in the pretreatment week to 4.11-5.67 in weeks 1-6 of XOS intake. XOS intake significantly alleviated the abdominal displeasure and feeling of residual stool leftness in weeks 2, 3, 5 and 6, while SUC did so in weeks 4 and 6 (p < 0.05). The coffee mixture containing xylooligosaccharide-sugar mixture reduced the abdominal displeasure and feeling of residual stool leftness from week 3 until the end of the experiment (p < 0.05). In conclusion, the XOS-sugar mixture intake was effective for the alleviation of constipation in the young women in this study, without adverse effects.
With regard to low dosage level, this study10 was particularly interesting since 40 healthy adult women were administered XOS at 0.4g (400 mg)/day for four weeks. Stool frequency was significantly increased during the period of XOS ingestion in the constipated subjects who defecated four times or less in a week before XO ingestion. Fecal quantity, consistency and color of feces and feeling after defecation were improved (P<0.05) by XOS ingestion in the subjects whose self-judged scores were low before XOS ingestion, and the satisfying state was maintained for two to four weeks after XOS ingestion was completed. The presence of Bifidobacteria in total intestinal flora was also significantly increased in the second week of XOS ingestion period (P<0.05). This effect was maintained during the period of XOS ingestion and returned to the original state after the termination.
Likewise, a 28-day study11 with 14 volunteers found that 1.4 g/day or 2.8 g/day XOS intake reduce stool hardness and effort to evacuate. In addition, a three-week controlled study12 with 22 elderly subjects (65 years and older) found that 4 g/day XOS significantly increased the population of Bifidobacteria and the fecal moisture content and decreased fecal pH value. Similarly, in a study13 with 10 men, both the hardness of feces and the frequency of diarrhea were decreased with administration of 2 g/day of XOS.
Prebiotics play a valuable role in nourishing friendly probiotic bacteria in our gut—although to realize associated benefits (e.g. increased bifidobacterial levels), a daily dose of 5 g or more is typically required. However, PreticX branded xylooligosaccharides (XOS), which have been shown to provide prebiotic benefits with just a dose of about 1 g/day and in one case as low as 400 mg/day. Additional benefits have also been demonstrated at higher doses.
1 Hutkins RW, Krumbeck JA, Bindels LB, Cani PD, Fahey G Jr, Goh YJ, Hamaker B7, Martens EC, Mills DA, Rastal RA, Vaughan E, Sanders ME. Prebiotics: why definitions matter. Curr Opin Biotechnol. 2016 Feb;37:1-7.
2 Finegold SM, Li Z, Summanen PH, Downes J, Thames G, Corbett K, Dowd S, Krak M, Heber D. Xylooligosaccharide increases bifidobacteria but not lactobacilli in human gut microbiota. Food Funct. 2014 Mar;5(3):436-45.
3 Childs CE, Röytiö H, Alhoniemi E, et al. Xylo-oligosaccharides alone or in synbiotic combination with Bifidobacterium animalis subsp. lactis induce bifidogenesis and modulate markers of immune function in healthy adults: a double-blind, placebo-controlled, randomised, factorial cross-over study. Br J Nutr. 2014 Jun 14;111(11):1945-56.
4 Yang J, Summanen PH, Henning SM, Hsu M, Lam H, Huang J, Tseng CH, Dowd SE, Finegold SM, and Heber D, Li Z. Xylooligosaccharide supplementation alters gut bacteria in both healthy and prediabetic adults: a pilot study. Front Physiol. 2015 Aug 7;6:216.
5 Sheu WH, Lee IT, Chen W, Chan YC. Effects of xylooligosaccharides in type 2 diabetes mellitus. J Nutr Sci Vitaminol (Tokyo). 2008 Oct;54(5):396-401.
6 Wayne HS, Lee I, Chen W, Chan Y. Effects of Xylooligosaccharides in Type 2 Diabetes Mellitus, J Nutr Sci Vitaminol. 2008;54:396-401.
7 Kyung, Myungok, Choe, HanSaem, Jung, Sangwon, Lee, Kyungsun, Jo, SungEun, Seo, Sheungwoo, Choe, Keunbum, Yang, Chang-Kun, Yoo, Sang-Ho, Kim, Yuri. Effects of xylooligosaccharide-sugar mixture on glycemic index (GI) and blood glucose response in healthy adults. J Nutr Health. 2014; 47(4):229-235
8 Nam, Hyekyoung, Kyung, Myungok, Seo, Sheungwoo, Jung, Sangwon, Chang, Moon-Jeong. Effect of different levels of xylooligosaccharide in sugar on glycemic index and blood glucose response in healthy adults. J Nutr Health. 2015;48(5):398-406.
9 Jeon, JH, Kyung, M, Jung, S, Jo, SE, Chang, MJ. Effect of xylooligosaccharide-sugar mixture on defecation frequency and symptoms in young women with constipation: a randomized, double-blind, placebo-controlled trial. J Nutr Health. 2015 Feb;48(1):19-29. Korean.
10 Iino T, Nishijima Y, Sawada S, et al. Improvement of constipation by a small amount of Xylooligosaccharides ingestion in adult women. Journal of Japanese Association for Dietary Fiber. 1997; 1(1): 19-24.
11 Na MH, Kim WK. Effects of xylooligosaccharide intake on fecal bifdobacteria, lactic acid and lipid metabolism in Korean young women, Korean J. Nutr. 2013; 40: 154–161.
12 Yun-Chin Chunga , Cheng-Kuang Hsub , Chih-Yuan Koa , Yin-Ching Chana. Dietary intake of xylooligosaccharides improves the intestinal microbiota, fecal moisture, and pH value in the elderly. Nutrition Research 27 (2007) 756–761.
13 Kobayashi T, Okazaki M, Fujikawa S, Koga K. Effect of xylooligosaccharides on Feces of Men. Nippon Nōgeikagaku Kaishi. 1991; 65(11):1651-1653.
Gene Bruno, MS, MHS, the dean of academics for Huntington College of Health Sciences, is a nutritionist, herbalist, writer and educator. For more than 30 years he has educated and trained natural product retailers and health care professionals, has researched and formulated natural products for dozens of dietary supplement companies, and has written articles on nutrition, herbal medicine, nutraceuticals and integrative health issues for trade, consumer magazines and peer-reviewed publications. He can be reached at email@example.com.