What are prebiotics?

Prebiotics act as energy and carbon sources for bacteria in the gut, enabling them to grow and multiply in numbers.

In 2017, the International Scientific Association for Probiotics and Prebiotics convened a panel of experts who updated the definition of a prebiotic to: 'a substrate that is selectively utilised by host microorganisms conferring a health benefit' 1

This update broadened the definition of prebiotics to also include: 

• Non-carbohydrate substrates such as polyphenols and polyunsaturated fatty acids (previously only carbohydrate substrates were included)

• Substrates that invoke changes to any host microbial ecosystem, not limited to the gastrointestinal microbiota

• Those administered directly to microbially colonised body sites, not limited to oral administration

• Those with targets beyond stimulation of bifidobacteria and lactobacilli 


For a substrate to be classified as a prebiotic, it must:

• Not be digested by the host

• Be selectively utilised by live host microorganisms in a manner that sustains, improves or restores host health

• Have demonstrated health benefits in the target host from well-controlled studies 

Sources of Prebiotics

Prebiotics can be found naturally in the diet, but are also becoming increasingly available as a supplement or added ingredient in foods. The dietary prebiotics most extensively studied with regards to prebiotic activity are the non-digestible oligosaccharides, such as fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS), but also inulin, lactulose and resistant starch.2 

Naturally occurring dietary sources of prebiotics include:

• Vegetables: Jerusalem artichokes, chicory, garlic, onion, leek, shallots, asparagus, beetroot, fennel bulb

• Legumes: Chickpeas, lentils, kidney beans, baked beans, soybeans

• Fruits: Bananas

• Wholegrains: Barley, rye, wheat, oats

• Nuts: Cashews, pistachios


Did you know... Synbiotics are the combined use of probiotics and prebiotics, that are known to work synergistically. The combination should consist of a prebiotic that specifically supports the survival and growth of the probiotic strain within the product.3

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