A Plethora of Prebiotics

Almost everyone has heard of probiotics and how helpful they can be for gut health, but the word “prebiotics” can seem a little confusing. The definition and scope of prebiotics have been evolving as researchers increase their understanding of prebiotic mechanisms in the body, but questions, such as how prebiotics differ from probiotics and how many types of prebiotics are there, remain.

What are prebiotics?

Prebiotics are a class of compounds recognized for their ability to be selectively utilized by host microbiota to the benefit of the host.1 The intestinal microbiome consists of many different types of microbes, and prebiotics provide the fuel for probiotics to thrive and support human health. For example, consumption of prebiotics may lead to increased numbers of beneficial bacteria such as Bifidobacterium and Lactobacillus, which can help stimulate the immune system and may help positively affect blood lipids.1 Essentially prebiotics are the food that probiotics need to spring into action within the gut.

A probiotic meal ticket

Prebiotics literally are the meals that probiotics need to consume in order to thrive and help support a healthy gut microbiota. Small amounts of prebiotics are found in certain foods. For example, the prebiotic inulin is found in asparagus, bananas, barley, chicory root, garlic, honey, Jerusalem artichoke, onions, and rye.2,3 Prebiotics are also found in mother’s milk (human milk oligosaccharides, or HMOs) and are thought to help colonize the infant’s intestinal microbiota with beneficial bacteria. 4  Supplementation with prebiotics directly delivers this fuel source to the probiotics in the gut.

Types of prebiotics

There are many types of prebiotics, including certain kinds of fats (CLA, conjugated linoleic acid, or PUFAs, polyunsaturated fatty acids), HMOs, phenolics and phytochemicals, readily fermentable dietary fibers, and oligosaccharides. 1 Oligosaccharides include fructose, glucose, galactose, mannose, and xylose. These are the most well-known prebiotics:

  • Inulin
  • Inulin is a nonviscous, soluble fiber that is readily fermented by gut microbiota.4
  • Plants that are rich in inulin include Jerusalem artichoke and chicory root. This prebiotic is also often added to dairy products and yogurts.
  • IMOs
  • Isomalto-oligosaccharides, or IMOs, are well-tolerated prebiotic soluble fibers that promote levels of bifidobacteria.5 IMOs are often used to sweeten cookies, biscuits, and nutritional food bars. In vitro, IMOs have been shown to help increase bifidobacteria levels and promote short-chain fatty acids (SFCA).6 IMO supplementation is associated with increased numbers of fecal bifidobacteria and lactobacilli.7
  • FOS
  • Fructo-oligosaccharides (FOS) are soluble fibers that have been extensively studied for their prebiotic effects, often in conjunction with inulin since FOS are shorter chains of inulin. FOS, in particular, has been shown to promote the abundance of Bifidobacterium within the gut microbiota.9 FOS is added to some yogurts and nutrition bars.
  • GOS
  • Galacto-oligosaccharides (GOS) are chains of galactose, which is enzymatically converted from lactose.10,11 GOS are added to some foods such as infant formula, dairy products, and nutrition bars.
  • HMOs
  • Human milk oligosaccharides (HMOs) are present in human milk and help promote the development of a newborn’s intestinal microbiota and immune system.12 Specific, nature-identical HMOs (not from human milk, yet structurally similar) are now being added to infant formulae with the intent of helping to support the infant’s immune system.13
  • Resistant starch
  • Resistant starches are compounds that cannot be digested in the small intestine. Instead, they pass to the colon where they are fermented by microbiota.14 Sources of resistant starch include unripe bananas, unprocessed whole grains, legumes, and various starchy vegetables such as potatoes.14
  • XOS
  • Xylo-oligosaccharides (XOS) are found in bamboo shoots, fruits, vegetables, milk, and honey,15 and are sometimes added to foods such as yogurt, candies, and drinks. Like other prebiotics, XOS are tapped for their ability to help maintain a balanced intestinal microbiota.15

How much?

While there isn't a standard or recommended amount yet, supplementation and/or consumption of foods with added prebiotics can help achieve daily intake of these important compounds.


Submitted by the Metagenics Marketing Team


  1. Gibson GR et al. Nat Rev Gastro Hepat. 2017;14:491-502.
  2. Moshfegh AJ et al. J Nutr. 1999;129(7):1407S-1411s.
  3. Aachary AA et al. Electron J Biotechn. 2017;26:46-51.
  4. Bode L. Nutrition Reviews. 67(s2):S183-S191.
  5. https://isappscience.org/prebiotics.EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies). Scientific Opinion on the substantiation of a health claim related to “native chicory inulin” and maintenance of normal defecation by increasing stool frequency pursuant to Article 13.5 of Regulation (EC) No 1924/2006. EFSA https://www.efsa.europa.eu/en/efsajournal/pub/3951 (2015).
  6. Rycroft C et al. J Appl Microbiol. 91, 878–887.
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  8. Yen C-H et al. Nutrition. 2011;27(4):445-450.
  9. Holscher H.. Gut Microbes. 2017 Mar 4;8(2):172-184.
  10. Tungland BC, Meyer D. Comprehensive Reviews in Food Science and Food Safety. 2002;1(3):90-109.
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  12. Musilova S et al. Beneficial Microbes. 2014;5(3):273-283.
  13. Plaza-Díaz J et al. Nutrients. 2018;10(8):1038.
  14. Birt D et al. Adv Nutr. 2013 Nov; 4(6): 587–601.
  15. Aachary AA et al. Compr Rev Food Sci F. 2011;10(1):2016.


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