Xylooligosaccharides
Also known as: Xylo-oligosaccharides, XOS, Xylooligosaccharides
Overview
Xylooligosaccharides (XOS) are prebiotic oligosaccharides composed of xylose units linked by β-1,4 glycosidic bonds. They are derived from the degradation of xylan, a component of plant cell walls, through various processes, and are found in small amounts in plant-based foods. XOS are recognized for their excellent water solubility, high thermal stability, and resistance to acidic pH. Their non-toxic nature, along with anti-inflammatory, antioxidative, and antimicrobial properties, makes them increasingly popular as dietary supplements for supporting gut health, enhancing nutrient absorption, and improving immune function. Emerging research indicates that XOS may also positively impact animal health, improving growth performance and disease resistance. However, more systematic reviews and meta-analyses are needed to fully understand their efficacy and safety across diverse populations.
Benefits
Evidence-based benefits of XOS include promoting gut health by enhancing the production of short-chain fatty acids (SCFAs) like butyric acid, as well as improving immune function through modulation of gut microbiota. Studies indicate that XOS can help improve nutrient digestibility and resistance to diseases, particularly in animal models. Research demonstrates notable improvements in animals such as piglets and laying hens, with enhancements in growth performance and reduction in diarrhea. In humans, preliminary findings suggest potential management of conditions like ulcerative colitis via promotion of beneficial gut bacteria. While the clinical significance of these benefits is still being assessed, a variety of studies show promise, particularly for gut health and immune function improvement within weeks of supplementation.
How it works
XOS function as prebiotics, selectively promoting the growth of beneficial gut bacteria like *Bifidobacterium* and *Lactobacillus*. They primarily affect the gastrointestinal system by influencing gut microbiota composition, which in turn enhances the production of SCFAs. SCFAs play a critical role in maintaining intestinal barrier integrity and regulating immune responses. Although specific molecular targets for XOS are not fully defined, they are known to influence gene expression relevant to gut barrier function and immune regulation. XOS are resistant to absorption in the small intestine, allowing them to reach the colon intact for fermentation by gut bacteria.
Side effects
XOS are generally considered safe for consumption with no reported toxicity. While extensive side effect data is lacking, some individuals may experience gastrointestinal discomfort, particularly when initiating supplementation. This discomfort may be more common in those with sensitive stomachs. No uncommon or rare side effects (<1%) have been identified in the literature, and no significant drug interactions are reported. Regarding contraindications, there are none specifically noted, although pregnant or breastfeeding women should consult healthcare providers before using XOS supplements due to limited safety data. Overall, their safety profile is favorable, but individual tolerance may vary.
Dosage
The minimum effective dose for humans is not well-established, but animal studies commonly use doses ranging from 100 to 400 mg/kg. While optimal human dosages are not precisely defined, up to several grams per day are typically used in prebiotic supplements. There is no clearly established maximum safe dose; however, high doses may lead to gastrointestinal discomfort. XOS can be taken at any time of day, although taking them with meals may help minimize potential side effects. They are available in various forms, including powders and capsules. Users should note that XOS are not absorbed in the small intestine, which means their effectiveness is not impacted by factors affecting absorption.
FAQs
Are XOS safe to take?
Yes, XOS are considered safe and well-tolerated, with no significant toxicity reported.
How should I take XOS?
XOS can be taken at any time; taking them with meals may help reduce gastrointestinal discomfort.
How long until I see benefits from XOS?
Improvements in gut health and immune function are often observed within weeks of consistent supplementation.
Can I experience side effects from XOS?
Some individuals, especially those with sensitive stomachs, may initially experience gastrointestinal discomfort.
What is a common misconception about XOS?
Many believe XOS provide direct nutritional benefits; however, they primarily act as prebiotics for beneficial gut bacteria.
Research Sources
- https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1189434/full – This study demonstrated improved nutrient digestibility and reduced diarrhea in weaning piglets fed high plant-based protein diets supplemented with XOS. The well-designed study outlined clear outcomes but is limited to animal models.
- https://pubmed.ncbi.nlm.nih.gov/34568407/ – Findings from this clinical study indicated that XOS positively influenced gut bacteria in patients with ulcerative colitis. Despite providing preliminary evidence of benefits in human health, the small sample size and limited duration were noted as limitations.
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2021.778542/full – Research involving laying hens showed that XOS supplementation led to enhancements in egg production and intestinal health. The study was well-structured and demonstrated potential benefits but was limited to animal models.
- https://pubmed.ncbi.nlm.nih.gov/39405830/ – This literature review highlighted the potential prebiotic effects of XOS, showing promise for enhancing health outcomes through modulation of gut microbiota and improvement of gut health.
- https://www.mdpi.com/2079-7737/11/4/553 – This meta-analysis provided a comprehensive overview of XOS research, emphasizing their safety and health benefits, particularly in gut health and immunity, while suggesting the need for more rigorous studies to validate findings.
Supplements Containing Xylooligosaccharides

Probiotics + Prebiotics Daily Balance
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Probiotics + Prebiotics Return to Regular
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Probiotics + Prebiotics Women's Daily
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Probiotic-10 & Bifido Boost
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Prebiotic Bifido Boost Powder
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Advanced Digestive Probiotic
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Precision Prebiotic Tropical Flavor
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Gut Soothe
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Prebiotic Bifido Boost Powder
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