Last updated June 2023

Each edition of GPA’s Prebiotic Spotlight focuses on a specific prebiotic type to raise awareness around the prebiotic itself, its sources, any notable and/or recent research, and how it is used in the marketplace. In this issue, xylooligosaccharides (XOS) are highlighted.

Overview
XOS is a functional oligosaccharide that has gained widespread attention in recent years from both scholars and industry for its prebiotic activity (Yan et al., 2022). XOS is a mixture of oligosaccharides containing β-1,4-linked xylose residues, naturally occurring in bamboo shoots, fruits, vegetables, milk, and honey (Divyashri et al., 2021). In the body, XOS gets fermented by Bifidobacterium spp. and Lactobacillus spp. in the microbiota, consequently increasing their relative abundance within the gastrointestinal tract and producing fecal short-chain fatty acids (SCFAs) (Lin et al., 2016).

Benefit Areas

• Inducing bifidogenesis (Childs et al., 2014; Finegold et al., 2014; Lin et al., 2016).
• Improving plasma sugar and lipid profiles in type 2 diabetes (Sheu et al., 2008; Yan et al., 2022).
• Positively altering the gut microbiota during the development of diabetes (Yang et al., 2015).
• Modulating immune function markers (Childs et al., 2014; Divyashri et al., 2021).
• Relieving constipation in pregnant and non-pregnant young women (Jeon et al., 2015; Tateyama et al., 2005).
• Relieving dysbiosis in the feces of ulcerative colitis patients in clinical remission (Li et al., 2021).

Sources
XOS is found naturally in bamboo shoots, milk, honey, fruits, and vegetables but can also be produced at an industrial scale by the hydrolysis of agro-industrial wastes, commonly known as lignocellulosic materials (LCMs) (Divyashri et al., 2021). These LCMs include corn cob, wheat and rice straws, tobacco stalks, sugarcane bagasse, and brewers’ spent grains, which are made via chemical, physical, and enzymatic methods (Batsalova et al., 2022; Yan et al., 2022). These processes vary in yield, purity, specificity, cost, and environmental impact (Chen et al., 2021), with enzymatic hydrolysis being faster and more eco-friendly than chemical and physical hydrolyses. Despite the absence of unwanted byproducts and reasonable yields, enzymatic modification presents several challenges, including enzyme cost, removal, stability, reuse, and substrate specificities. As such, researchers continue to work towards optimizing XOS manufacturing by combining methods and testing different raw materials, extraction approaches, and enzymes to achieve a cost-effective and healthful product with optimal production efficiency (Batsalova et al., 2022).

Dose Range
XOS is available in powder or tablet format as standalone or combined with probiotics or other prebiotics. Prebiotic and bifidogenic effects of XOS have been shown at doses as small as 1.4 g/day for eight weeks (Finegold et al., 2014), which is considerably less than the amount needed for other prebiotics. Nonetheless, the study demonstrated more significant changes in various gastrointestinal microbiota species at a 2.8 g/day dose of XOS (Finegold et al., 2014). More commonly, studies use a dose of 4-8 g/day (Childs et al., 2014; Sheu et al., 2008; Tateyama et al., 2005). XOS has obtained Generally Recognized as Safe (GRAS) status by the United States (US) Food and Drug Administration (FDA) and has been accepted as a safe novel food pursuant by the European Food Safety Authority (EFSA) after evaluating a XOS product enzymatically produced from corncob (Batsalova et al., 2022; EFSA, 2018). In Canada, XOS from corncob and sugarcane received a non-novel determination for use as food and food ingredients (Health Canada Food Directorate, 2023). Additionally, XOS is classified as an acceptable Natural Health Product (NHP) medicinal ingredient (Health Canada Natural and Non-prescription Health Products Directorate, 2023) and several licensed finished NHPs containing XOS are available in the marketplace either as a single-ingredient or part of a multi-ingredient formulation (Health Canada Licensed NHPs Database, 2023). 

Recent Research
On ClinicalTrials.gov, one study is currently recruiting to study XOS in irritable bowel syndrome (IBS) (ClinicalTrials.gov, 2023). On PubMed, the term “xylooligosaccharides” retrieved 41 studies published this year, focusing on various production and optimization methods of XOS (PubMed, 2023). When the same term was used in the Cochrane Library, 33 results were retrieved (Cochrane Library, 2023), including three recruiting trials registered with the Chinese Clinical Trial Registry. These trials aim to study the effect of XOS on gut microbial changes, adverse events, and bioavailability of chemotherapy drugs in colorectal cancer patients (Chen et al., 2023), changes in physiological and biochemical indicators of cholecystectomy (CHICTR, 2023a), and the microenvironment of facial skin (CHICTR, 2023b). One recent study by McFarlin et al. (2022) aimed to determine the effect of a 90-day probiotic/prebiotic supplementation on mRNA associated with inflammation and chronic disease risk in overweight adults. A significant reduction in visceral adipose tissue and the expression of mRNA associated with adipose tissue inflammation, systemic inflammation, and chronic disease risk was reported with 0.8 g/day of XOS combined with one billion colony-forming units/day of Bacillus subtilis HU58 and Bacillus coagulans SC-208. In addition to its anti-inflammatory properties, XOS has been explored for its anticancer potential. Batsalova et al. (2022) employed an in vitro model showing that XOS exerts its anti-tumor effect by modulating toll-like receptor 4 (TLR4) signaling and glutathione homeostasis, consequently affecting the cellular redox state. These properties of XOS make it a possible component for use in anticancer therapeutics and nutraceutical applications.

How is XOS used in the marketplace?
With an increasing interest in employing dietary interventions to improve health and wellness, prebiotics are showing promise as functional candidates to obtain various health benefits, particularly XOS.

XOS exhibits unique physicochemical properties such as low viscosity, excellent water solubility, high-temperature resistance, and acidic pH resistance, as well as functional biological activities such as anti-inflammation, antioxidative, antitumor, and antimicrobial properties (Chen et al., 2021; Yan et al., 2022). Additionally, XOS has a sweetness of about 40% coming from sucrose; therefore, it can be used as an alternative to sugar (Yan et al., 2022). These characteristics make XOS a desirable candidate for human nutritional applications.

XOS is used as an ingredient in various functional foods, including soy milk, soft drinks, tea, cocoa drinks, nutritive preparations, dairy products with milk, milk powder, and yogurt, candies, cakes, baked goods, pudding, jellies, jam, and honey products, either as a food additive or components of a synbiotic formulation (Aachary & Prapulla, 2010).

The global XOS market sales are estimated to reach $74 million USD in 2023 and are projected to increase by 7% compound annual growth rate (CAGR) in the next ten years to reach $144.5 million USD in 2033 (Future Market Insights, 2023).

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