Fructooligosaccharides (FOS) are gaining attention as consumers and food manufacturers alike focus more on gut health and functional nutrition. As a plant-derived prebiotic fibre, FOS offers unique benefits for digestion, metabolic health, and product formulation. From supporting beneficial gut bacteria to helping reduce sugar and calorie content in food, FOS plays a crucial role in modern dietary trends.
In this article, we explore what fructooligosaccharides are, how they function, and why they are increasingly used in innovative food products.
What are Fructooligosaccharides (FOS)?
Fructooligosaccharides belong to a group of soluble dietary fibres composed of short chains of fructose molecules. As carbohydrates, they fall under the classification of oligosaccharides, meaning they consist of a few simple sugar units linked together. Unlike starches or other carbohydrates, FOS molecules remain undigested in the upper gastrointestinal tract, reaching the colon where they serve as a food source for beneficial gut bacteria.
While all dietary fibres resist digestion, FOS differ from insoluble fibres like cellulose because they dissolve in water and take on a gel-like consistency. This solubility influences digestion and absorption, setting FOS apart from resistant starches or long-chain fibre compounds.
Nutritional Benefits of Fructooligosaccharides?
Fructooligosaccharides contribute to various physiological benefits, primarily due to their classification as soluble prebiotic fibres. Their low caloric value and resistance to enzymatic digestion in the human small intestine make them beneficial for metabolic health.
–Role in Promoting Gut Bacteria Balance
FOS selectively stimulates the growth of beneficial gut bacteria in the colon, specifically Bifidobacteria and Lactobacillus, by serving as a fermentable substrate. These bacteria thrive on FOS, outcompeting potentially harmful microorganisms in the gut.
–Impact on Overall Digestive Health
FOS positively influences digestion by modulating intestinal transit time and improving stool consistency. Its water-retaining properties contribute to softening stool, making it beneficial for individuals experiencing occasional constipation.
In addition to regulating bowel movements, FOS interacts with the gut-brain axis. Research suggests that prebiotics, including FOS, may influence mood and cognitive function by modulating gut microbial metabolites, although further investigations are needed.
FOS as a Functional Ingredient
FOS fits seamlessly into the functional food category. Their ability to enhance gut microbiota, improve digestion, and contribute to overall metabolic health elevates their status. Food manufacturers integrate FOS into a variety of products, not just for their mild sweetness, but also for their physiological benefits and ability to reduce sugar in applications.
Functional foods provide health advantages beyond essential nutrition, and FOS plays a significant role in this market. FOS enhances mineral absorption, particularly calcium and magnesium, supporting bone health. Their low caloric value and probiotic properties make them valuable in formulation products aimed at digestive support, metabolic health, and immune function. Additionally, when used without other added sugars, FOS enables manufacturers to create “no added sugar” formulations, meeting consumer demand for lower-sugar products without compromising taste or texture.
Various food categories incorporate FOS, including:
- Dairy Alternatives: Added to plant-based yoghurts and milk substitutes to mimic the prebiotic effect of dairy.
- Bakery Products: Used in bread and cereal bars to improve texture while enhancing fibre content.
- Beverages: Found in functional drinks designed to promote gut health.
- Nutritional Supplements: Common in fibre-rich formulas or symbiotic products combining probiotics and prebiotics.
Consumer Demand for Well-Being
Health-conscious consumers seek ingredients that offer more than basic nutrition, resulting in a rising demand for a fibre-enhanced products. FOS aligns with consumer preferences for natural, fibre-rich, and gut-friendly food components.
Factors driving this demand include:
- Increased awareness of gut health: Consumers recognise the link between microbial balance and overall wellness.
- Interest in sugar reduction: FOS provides mild sweetness with fewer calories, aligning with reduced sugar consumption trends.
- Preference for plant-based ingredients: As a plant-derived fibre, FOS appeals to vegan and vegetarian consumers.
Product developers continuously explore innovative ways to integrates FOS into formulations, ensuring food and drink options that support digestive health while meeting taste and texture expectations.
Fructooligosaccharides as a Prebiotic
Prebiotics, probiotics, and postbiotics all play important yet distinct roles in gut health. Prebiotics are non-digestible fibres that promote the growth and activity of beneficial bacteria. Probiotics are live microorganisms that directly contribute to maintaining or restoring a healthy gut microbiome. Postbiotics, meanwhile, are the metabolic byproducts or compounds produced when probiotics ferment prebiotics—these include short-chain fatty acids and other bioactive substances that support gut barrier function, immune response, and overall gut health.
FOS belongs to the prebiotic category, stimulating the activity of specific microorganisms such as Bifidobacteria and Lactobacilli.
How FOS Functions as a Prebiotic
Once consumed, FOS resists digestion in the upper gastrointestinal tract and reach the colon largely intact. There, gut microbiota ferment these short-chain fructans, producing short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate. These SCFAs contribute to colon health by lowering pH, enhancing mineral absorption, and supporting intestinal barrier integrity.
The fermentation of FOS by beneficial bacteria leads to a shift in microbial composition, increasing populations of health-promoting species. Higher concentration of Bifidobacteria and Lactobacilli correlate with improved intestinal function and reduced prevalence of harmful bacteria like Clostridium and Escherichia coli.
What is the difference between FOS and Inulin?
Fructooligosaccharides (FOS) and Inulin are both types of nondigestible carbohydrates known as fructans, composed primarily of fructose units. They are considered prebiotic fibres, meaning they resist digestion in the upper gastrointestinal tract and are fermented by beneficial bacteria in the colon.
- Inulin is a longer-chain fructan, typically containing more than 10 fructose units.
- FOS has a shorter chain length, generally between 2 and 7 fructose units.
Although both substances promote the growth of beneficial gut bacteria, particularly Bifidobacteria and Lactobacilli, they differ in functional properties such as solubility, sweetness, and tolerance levels.
From a labelling perspective, regulations may distinguish between inulin and FOS depending on chain length, origin, and processing method. In the EU, for example, FOS and inulin may be labelled separately, particularly when highlighting prebiotic content or fibre functionality. However, in commercial contexts, “inulin-type fructans” may serve as an umbrella term for both.
What are the Natural Sources of Fructooligosaccharides in Food?
FOS occurs naturally in various plant-based foods. Many vegetables, fruits, and grains contain significant amounts, contributing to dietary fibre intake. Incorporating these foods into your meals increases fibre consumptions and supports gut health.
Food that are naturally rich in FOS includes…
- Onions – 2 to 6g per 100g
- Garlic – 9 to 16g per 100g
- Leeks – 3 to 10g per 100g
- Asparagus – 2 to 3g per 100g
- Bananas – 0.3 to 0.5 per 100g
- Chicory Root – 15 to 20g per 100g
- Jerusalem Artichoke – 16 to 20g per 100g
- Wheat and Rye – 1 to 4g per 100g
Fibre Content in Modern Diets
Average fibre intake in Western diets often falls below recommended levels. The recommended fibre intake for adults in the UK is 30 grams per day, yet actual consumption average is around 18 grams daily, 60% of what it should be! Food products often reference if they are a source of fibre (>3g per 100g) or high in fibre (>6g per 100g). Look out for these when picking pre-packaged food items!
Applications of Fructooligosaccharides in Food Manufacturing
Food manufacturers integrate FOS into a wide range of products due to their prebiotic properties and mild sweetness. They appear in baked goods, dairy alternatives, cereals, and nutritional bars. Beverage formulations also benefit from FOS, particularly in probiotic drinks where they enhance gut health benefits. Infant formula manufacturers include FOS to mimic the oligosaccharides naturally present in human milk, supporting early microbiome development.
FOS comes in different forms to meet specific production needs. Powdered FOS blends seamlessly with dry ingredients, making it ideal for baking and powdered drink mixes. FOS Syrup provides effortless solubility for beverages, nutrition bars, and dairy applications. Manufacturers also use high-purity FOS syrups in sugar-reduced formulations, ensuring desirable sweetness without excessive calories. When used as the sole sweetener, these forms of FOS can support a no added sugar claim, offering both technical and labelling advantages in health-conscious product development.
–Functional Advantages of FOS for Texture and Stability
Beyond its nutritional benefits, FOS contributes to product quality in several ways. It enhances texture in baked goods, improving moisture retention and shelf life. In dairy products, it prevents crystallisation in frozen desserts and supports a creamy consistency. Due to its water-binding properties, FOS maintains the softness of reduced-sugar confections while ensuring stability in moisture-sensitive products. The prebiotic also withstands high processing temperatures, making it compatible with pasteurisation and extrusion.
–Fructooligosaccharides in Dairy Products
FOS transforms dairy products by improving texture, enhancing probiotic viability, and boosting prebiotic benefits. As non-digestible carbohydrates, FOS serves as a fermentation substrate for beneficial gut bacteria, particularly Lactobacillus and Bifidobacterium, which are common in yoghurt and kefir.
When incorporated into dairy formulations, FOS contribute to a creamier consistency while reducing syneresis, the undesired separation of whey. Their mild sweetness, approximately 30-50% as sweet as sucrose, helps balance flavour without increasing sugar content. Additionally, their ability to retain water enhances the smoothness of fermented dairy textures.
- Improved Probiotic Survival: FOS protects live bacterial cultures, increasing their resilience during production, storage, and digestion.
- Prebiotic Synergy: The combination of probiotics and FOS creates symbiotic effects, fostering microbiome health.
- Enhanced Texture and Taste: Acting as a natural bulking agent and mild sweetener, FOS helps to refine mouthfeel without artificial additives.
The global market for functional dairy has expanded with growing consumer demand for gut-friendly products. Yoghurt and kefir brands now emphasise prebiotic components alongside probiotics, responding to increasing awareness about the gut microbiome.
- Low-Sugar Innovation: FOS enables sugar reduction in flavoured yoghurts while preserving palatability.
- Plant-Based Alternatives: Addition to FOS in non-dairy yoghurts enhances fibre content and improves texture in almond, soy, and coconut-based varieties.
- Gut Health Marketing: Dairy products emphasise prebiotic ingredients as a competitive advantage in functional food sectors.
What is the Impact of Fructooligosaccharides on Sugar Replacement and Calorie Reduction?
FOS provide sweetness while lowering the need for added sugars in processed foods. With approximately 30-50% of the sweetness intensity of sucrose, FOS contributes to a mild, pleasant taste without significantly raising blood glucose levels. Food manufacturers use it to enhance flavour profiles while offering a low-glycaemic alternative to traditional sweeteners.
FOS blends well with high-intensity sweeteners like stevia or monk fruit, improving product texture and reducing the aftertaste that some sweeteners create. This makes it an effective tool for formulating reduced-sugar versions of baked goods, beverages, and dairy products.
With regards to calorie reduction, each gram of FOS provides only 1 to 2 kcal, significantly lower than the 4 kcal per gram found in sucrose. This reduction makes a meaningful difference in daily caloric intake when FOS replaces a portion of added sugars in a diet.
Since FOS is not fully digested in the small intestine, it contributes fewer absorbable calories than conventional carbohydrates. This characteristic makes it particularly appealing to individuals managing weight or blood sugar levels.
Products formulated with FOS can maintain desirable texture and mouthfeel while supporting dietary goals. The bulking properties of FOS help replicate the structural functions of sugar in baked goods and frozen desserts, ensuring consistent quality in reduced-calorie formulations. When used without added sugars, FOS can also support a “no added sugar” claim, aligning with consumer demand for lower-sugar products without compromising on texture.
Considerations and Limitations of FOS
Fructooligosaccharides (FOS) are widely used and generally well tolerated, but they are not without their challenges. Depending on the application and the consumer, there are several important factors to keep in mind when working with FOS.
–Digestive Sensitivity and FODMAP Considerations
FOS is a fermentable fibre, which means it is broken down by bacteria in the colon. While this process can offer prebiotic benefits, it may also result in unwanted side effects, such as bloating, gas, and mild gastrointestinal discomfort, particularly in sensitive individuals. For this reason, FOS may not be suitable for those adhering to a low-FODMAP diet, commonly followed by people managing irritable bowel syndrome (IBS) and other digestive conditions.
–Limitations in Fermented Applications
In certain fermented food applications, FOS may not be able to fully replace sugar as the primary fermentation substrate. This could influence fermentation behaviour, potentially altering flavour, texture, or process outcomes depending on the product.
–Moisture Sensitivity and Product Stability
Another consideration is FOS’s high solubility, which can lead to moisture absorption in specific formulations. In dry goods, for example, this characteristic may negatively impact texture and shelf life, requiring additional formulation adjustments to maintain product quality.
While FOS offers functional and nutritional benefits, understanding these limitations is key to ensuring optimal performance across different food and beverage applications.
Regulatory Aspects of FOS
–FOS and its GRAS Status
In the UK, FOS is regulated under retained EU law following Brexit and continues to be recognised as a dietary fibre, permitted for use in food products provided it meets applicable labelling and compositional requirements.
The U.S. Food and Drug Administration (FDA) has classified fructooligosaccharides as Generally Recognised As Safe (GRAS).
Beyond the U.S., regulatory agencies in other regions have also granted approvals. The European Food Safety Authority (ESFA) includes FOS within its regulations on dietary fibres and prebiotics, while Japan has approved it as a functional component under its Food for Specified Health Uses (FOSHU) program.
–FDA Regulations on the Use of FOS
In the United States, FOS falls under the category of dietary fibres and serve as an ingredient in functional foods, dietary supplements, and infant formula. The FDA allows its inclusion in a wide range of food products, provided manufacturers comply with labelling and compositional standards.
- Labelling Requirements: Ingredients list must specify FOS, and products making fibre-related claims must comply with the FDA’s definition of dietary fibre.
- Usage Limits: While no strict upper limit exists, manufacturers typically follow scientifically backed doses to ensure efficacy and avoid digestive discomfort.
- Infant Formula Use: The FDA permits FOS in infant formula, considering evidence of its role in promoting beneficial gut bacteria.
–Global Considerations
Regulatory guidelines for FOS vary worldwide.
The EU maintains a clear framework for dietary fibres, recognising FOS as prebiotic. In Canada, its use in functional foods aligns with dietary fibre regulations. Asian markets, particularly China and Japan, also allow its inclusion in health-oriented food products.
As interest in prebiotic fibres grows, regulatory scrutiny continues to evolve. Agencies assess new dietary applications, refining guidelines to ensure consumer safety and efficacy. Keeping up with these changes remains essential for manufacturers incorporating FOS into their products.
Please note: The information provided above is for reference and informational purposes only. Ingredient use and health-related claims should always be evaluated in the context of local regulatory frameworks. We recommend consulting the relevant authorities or regulatory experts to ensure compliance within your specific market.
Consumer Trends Towards Fibre and Gut Health
–The Rising Demand for Dietary Fibre
Consumers increasingly prioritise gut health, driving demand for fibre-rich products. According to a 2023 report by Innova Market Insights, 65% of global consumers recognise the link between digestive health and overall well-being. This awareness fuels the functional fibre market.
Food manufactures have responded by integrating prebiotic fibres such as FOS into various products. An analysis by FMI Future Market Insights predicts the global prebiotic market will reach $10.9 million by 2033 (from $6.68 million in 2023), significantly driven by FOS applications in food and beverages.
–Consumer Shifts in Diet and Lifestyle
Dietary choices increasingly reflect a preference for natural and functional ingredients. This trend aligns with the growing popularity of plant-based diets, in which FOS serves as a key ingredient due to its fibre-enhancing properties.
–Impact on Product Innovation and Labelling
Consumers scrutinise ingredient lists and favour products with clean labels. The demand for transparency led to greater inclusion of terms such as “prebiotic fibre” and “supports digestive health” on packaging.
–Regional Differences in Fibre Consumption
Interest in dietary fibre varies by region. In Europe, regulatory guidelines promote fibre-enriched diets, leading to an expansion of FOS-based products. In the Asia-Pacific, probiotic and prebiotic combinations thrive due to traditional fermented food consumption patterns. North America registers strong demand for digestive wellness products in response to rising gut health concerns.
–Future Outlook on Fibre-Driven Consumption
The trajectory for fibre-enriched foods remains strong, with sustained innovation in prebiotic applications. As scientific research continues to emphasise the gut microbiome’s influence on gut health, industry leaders integrate FOS into mainstreams food and beverage categories.
How can we help?
With decades of expertise in ingredient sourcing and supply, we are proud to partner with Zukan, a leading supplier of high-quality Fructooligosaccharides (FOS). We serve a diverse range of customers across the UK and beyond, from innovative startups to established brands in categories such as functional foods, sports nutrition, and plant-based products.
Contact a member of our team by emailing enquiries@lehmanningredients.co.uk or calling +44 (0) 1524 581560.
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Frequently Asked Questions
FOS are soluble dietary fibres made of short chains of fructose molecules. They resist digestion in the upper gut and reach the colon where they feed beneficial gut bacteria, promoting digestive health.
FOS selectively stimulate the growth of beneficial bacteria like Bifidobacteria and Lactobacillus. They improve digestion by softening stool, regulating bowel movements, and may even influence mood via the gut-brain axis.
Prebiotics like FOS are non-digestible fibres that feed beneficial bacteria. Probiotics are live beneficial bacteria. Postbiotics are compounds produced when probiotics ferment prebiotics, supporting gut and immune health.
FOS is added to dairy alternatives, bakery items, beverages, and supplements for its mild sweetness, fibre content, and ability to reduce sugar while improving texture and gut health benefits.
FOS selectively stimulate the growth of beneficial bacteria like Bifidobacteria and Lactobacillus. They improve digestion by softening stool, regulating bowel movements, and may even influence mood via the gut-brain axis.
Prebiotics like FOS are non-digestible fibres that feed beneficial bacteria. Probiotics are live beneficial bacteria. Postbiotics are compounds produced when probiotics ferment prebiotics, supporting gut and immune health.
FOS is added to dairy alternatives, bakery items, beverages, and supplements for its mild sweetness, fibre content, and ability to reduce sugar while improving texture and gut health benefits.
Yes. FOS provides 30-50% of the sweetness of sugar but with fewer calories (1-2 kcal per gram versus 4 kcal per gram in sugar). It helps create lower-sugar or “no added sugar” products without compromising taste or texture.
Some people may experience bloating, gas, or mild digestive discomfort, especially those sensitive to FODMAPs or with IBS. Also, FOS can affect texture in certain dry or fermented foods and absorb moisture, so formulation adjustments may be needed.
FOS naturally occurs in foods like onions, garlic, leeks, asparagus, bananas, chicory root, Jerusalem artichoke, wheat, and rye.
Both are fructans and prebiotic fibres, but Inulin has longer chains (over 10 fructose units) while FOS has shorter chains (2–7 units). They have different functional properties and may be labelled separately in some regions.
Yes. FOS is Generally Recognised As Safe (GRAS) by the FDA and approved by regulatory bodies worldwide, including EFSA and Japan’s FOSHU program, when used within recommended guidelines.
Rising awareness of gut health, demand for lower-sugar and plant-based foods, and the trend towards natural functional ingredients are driving increased use of FOS in food products globally.
