Prebiotic Type Spotlight: Human Milk Oligosaccharides (HMOs)

Last Updated October 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, human milk oligosaccharides (HMOs) are highlighted.

Human breast milk is primarily comprised of lactose, lipids, and HMOs. The composition of HMOs varies from person-to-person, based on genetic and environmental factors such as ethnicity, geographical location, lactation stage, infant age, and maternal health, age, and nutrition (Corona et al., 2021). A further breakdown of HMOs illustrates that they are complex, unconjugated glycans naturally and abundantly found in human milk at concentrations ranging from 20 – 24 g/L in early milk (i.e., colostrum) to 10 – 15 g/L in more mature milk (Triantis et al., 2018; Zhang et al., 2021). There are over 200 known HMO structures that uniquely consist of five simple sugars (D-glucose, D-galactose, L-fucose, N-acetyl-D-glucosamine (GlcNAc), and N-acetylneuraminic acid (Neu5A)), and new HMO structures are continually being identified with the ongoing advancement of analytical methods (Palur et al., 2023). These indigestible oligosaccharides are responsible for providing prebiotic, immunological, anti-pathogen, as well as gut and intestinal health properties; therefore, human milk is considered the gold standard of infant nutrition by the World Health Organization (Palur et al., 2023; Zhang et al., 2021). With breastfeeding rates on a global decline and an enhanced public interest in prebiotic supplementation, the development of HMOs for formula, food, and other health applications is an exciting opportunity to take advantage of these unique sugars and their wellness properties.

Benefit Areas
By the end of the 1800’s, it was observed and documented that the survival rate of breastfed infants was seven times higher in comparison with infants who were fed bottles that contained a variety of pureed foods, meats, animal milk, cereals, or homemade modified cow’s milk formula, and vast differences in fecal composition between breastfed and bottle-fed infants were apparent (Zhang et al., 2021; Kunz, 2012). These historic observations paved the way for accelerated HMO research over the past century, and significant progress has been made to better understand the structural composition and health functions of HMOs. Some of these identified health benefits include:

  • Supporting the production of secondary microbial metabolites (Hill et al., 2023).
  • Enhancing cognitive, language, and motor skill development in infants (Berger et al., 2020; Berger et al., 2023).
  • Protecting against atopic dermatitis/eczema in infants (Rahman et al., 2023).
  • Stimulating the growth of beneficial Bifidobacterium in infants and adults (Wallingford et al., 2022; Elison, 2016).
  • Maintaining gastrointestinal health, preventing pathogens, and supporting immunity in infants (Triantis et al., 2018; Wiciński et al., 2020; Salamone & Di Nardo, 2020; Zhang et al., 2021; Hegar et al., 2019; Vandenplas et al., 2018).

While HMOs are a natural component found in human milk, recent developments in HMO synthesis have set forth industrial production of chemically and structurally identical oligosaccharides to HMOs found in human milk (Hill & Buck, 2023). Chemical and enzymatic synthesis along with fermentation are the current production methods used for manufacturing HMO molecules (Zeuner et al. 2019). Chemical synthesis is a time-consuming process that produces low yields, involves toxic reagents and transition metal catalysts, and is not a cost-efficient method of large-scale HMO production (Zeuner et al., 2019). Improvements in enzymatic HMO production have been made over the past few decades, however, structural discrepancies may remain between HMOs that are enzymatically synthesized and HMOs that are naturally found in human milk (Zeuner et al., 2019). The most promising technology for the enzymatic manufacturing of HMOs is via glycosidase-catalyzed transglycosylation, potentially producing diverse HMO structures and exhibiting significant yields (Zeuner et al., 2019). Additionally, chemoenzymatic synthesis has emerged as an alternative method of production, combining the chemical and enzymatic synthesis methods, resulting in 31 different HMOs, an unparallel number of diverse HMOs that have been produced to date (Palur et al., 2023). Although cost-efficient fermentation technology has improved, this production method is limited for complex HMOs, as concentration yields are often low or the product can remain in an unusable state (Zeuner et al., 2019). The first HMOs produced via industrial fermentation of E. coli include 2’-fucosyllactose (2’-FL), and these oligosaccharides are currently found in infant formula preparations in more than 30 countries (Zeuner et al., 2019). Both oligosaccharide compounds have been recognized as safe with the European Food Safety Authority (EFSA) and the U.S. Food and Drug Administration (FDA). Numerous Generally Recognized As Safe (GRAS) notices have been issued by the FDA for 2’-FL ingredients from as early as October 10, 2014 to as recent as April 4, 2023, establishing a history of safe use. In Canada,  2’-FL can be considered both a medicinal ingredient and a novel food as assessed by Health Canada’s Food Directorate, since it is derived from a genetically modified bacterium (E. coli). Health Canada had no objections to the use of this HMO as a food ingredient in formulas for infants and young children. 

Dose Range
The following dose ranges have been established via clinical trial data and scientific reviews:

  • 2 – 2.4 g/L of 2’-FL per day for infants
  • 24 – 12.0 g/kg of 2’-FL per day for young children
  • 2 – 20 g/kg of 2’-FL per day for adults

Recent Research
Currently, there are six studies actively recruiting on proposing HMOs for use as a prebiotic or supplement, evaluating if HMOs can improve renal transplant outcomes in adults, bowel motility in neurogenic bowel and bladder patients, symptoms of irritable bowel syndrome in healthy adults, the efficacy and tolerability of HMOs for colic management in infants 2-8 weeks of age, the growth of healthy infants less than one month of age by comparing HMO supplemented formula with standard formula, and the effects of synbiotics (2’-FL and Bifidobacterium infantis probiotic) on infectious morbidity and growth rates in infants 3-6 weeks of age (, 2023). Moreover, searching “human milk oligosaccharides” on PubMed retrieved 125 results published this year, highlighting the beneficial properties of HMOs, the compositional differences, and various health applications such as skin and gut health, infant neurodevelopment, regenerative potential, immunological potential, iron absorption, and others (PubMed, 2023). A study by Araki et al. (2023) examined the effects of 2’-FL on early life stress-induced anxiety in adulthood by performing behavioral, neuronal, and fecal microbiota analyses in early-weaned mice after treatment with 2’-FL. The results of this study showed that early weaning induced anxiety-like behaviors, increased neural abnormalities, and changed the fecal microbiota composition, and that ingestion of 2’-FL alleviated these adverse effects. An additional study by Hill et al. (2023) examined the serum metabolite levels of infants fed formula supplemented with 2’-FL compared to breastfed infants and observed that the supplemented infant formula significantly increased serum metabolites derived from microbial activity in the gastrointestinal tract. These results provide further evidence that HMOs can support gut health. Furthermore, an interesting review completed by Rahman et al. (2023) demonstrated that the role HMOs play in metabolizing bacteria may protect against atopic dermatitis/eczema.

How are HMOs used in the marketplace?
HMOs are currently being incorporated into various food applications such as formula for infants and toddlers, infant and toddler foods (i.e., ready-made cereals and snacks), meal replacement beverages, bars, breakfast bars, non-carbonated sports drinks, and flavored waters, etc., throughout the United States and Europe. In Canada, HMOs have been formulated into infant and toddler formulas as well as prebiotic powders and liquids for infants, children, pregnant and breastfeeding mothers, and adults for the purposes of maintaining immune function, supporting gastrointestinal health, reducing the risk of developing childhood eczema/atopic dermatitis and many others.

The HMO market was estimated at USD 199.00 million in 2022 and is projected to grow at a 22.7 % compound annual growth rate (CAGR) to reach $1.5 billion USD by 2032 (Future Market Insights, 2022). As the population grows, there is an increased demand for nutritional infant food and with the numerous health benefits HMOs provide, the demand for HMO supplemented products is apparent.

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Araki, R., Tominaga, Y., Inoue, R., Kita, A., & Yabe, T. (2023). 2’­-Fucosyllactose Alleviates Early Weaning-Induced Anxiety-Like Behavior, Amygdala Hyperactivity, and Gut Microbiota Changes. The Pharmaceutical Society of Japan, 46(6):796-802.

Berger, P.K., Ong, M.L., Bode, L., & Belfort, M.B. (2023). Human Milk Oligosaccharides and Infant Neurodevelopment: A Narrative Review. Nutrients, 15(719).

Berger, P.K., Plows, J.F., Jones, R.B., Alderete, T.L., Yonemitsu, C., Poulsen, M., Hoon Ryoo, J., Peterson, B.S., Bode, L., & Goran, M.I. (2020). Human milk oligosaccharide 2’-fucosyllactose links feedings at 1 month to cognitive development at 24 months in infants of normal and overweight mothers. PLOS ONE, 15(2):e0228323.

Corona, L., Lussu, A., Bosco, A., Pintus, R., Cesare Marincola, F., Fanos, V., & Dessì, A. (2021). Human Milk Oligosaccharides: A Comprehensive Review towards Metabolomics. Children, 8(9):804. Retrieved on 2023 Jun 26. Available from:

Elison E., Vigsnaes, L.K., Rindom Krogsgaard, L., Rasmussen, J., Sørensen, N., McConnell, B., Hennet, T., Sommer, M.O., & Bytzer, P. (2016). Oral supplementation of healthy adults with 2′-O-fucosyllactose and lacto-N-neotetraose is well tolerated and shifts the intestinal microbiota. British Journal of Nutrition, 116(8):1356-1368.

Future Market Insights. Human Milk Oligosaccharides Market Snapchat (2022-2032). Retrieved on 2023 Jun 27. Available from:

Hegar, B., Wibowo, Y., Basrowi, R.W., Ranuh, R.G., Sudarmo, S.M., Munasir, Z., Atthiyah, A.F., Widodo, A.D., Supriatmo, Kadim, M., Suryawan, A., Diana, N.R., Manoppo, C., & Vandenplas, Y. (2019). The Role of Two Human Milk Oligosaccharides, 2′-Fucosyllactose and Lacto-N-Neotetraose, in Infant Nutrition.   Pediatric Gastroenterology, Hepatology, & Nutrition, 22(4):330-340.

Hill, D.R. & Buck, R.H. (2023). Infants Fed Breastmilk or 2’-FL Supplemented Formula Have Similar Systemic Levels of Microbiota-Derived Secondary Bile Acids. Nutrients, 15(10):2339.

Kunz, C. (2012). Historical Aspects of Human Milk Oligosaccharides. Advances in Nutrition, 3(3):430S-439S.


Palur, D.S.K., Pressley, S.R., & Atsumi, S. (2023). Microbial Production of Human Milk Oligosaccharides. Molecules, 28(3):1491.

PubMed. Human Milk Oligosaccharides. Retrieved on 2023 Jun 27. Available from:

Rahman, T., Sarwar, P.F., Potter, C., Comstock, S.S., & Klepac-Ceraj, V. (2023). Role of human milk oligosaccharide metabolizing bacteria in the development of atopic dermatitis/eczema. Frontiers in Pediatrics, 11.

Salamone, M. & Di Nardo, V. (2020). Effects of human milk oligosaccharides (HMOs) on gastrointestinal health. Frontiers in Bioscience, Elite, 12:183-198.

Triantis, V., Bode, L., & van Neerven, R.J.J. (2018). Immunological Effects of Human Milk Oligosaccharides. Frontiers in Pediatrics, 6(190).

Vandenplas, Y., Berger, B., Carnielli, V.P., Ksiazyk, J., Lagström, H., Sanchez Luna, M., Migacheva, N., Mosselmans, J.M., Picaud, J.C., Possner, M., Singhal, A., & Wabitsch, M. (2018). Human Milk Oligosaccharides: 2′-Fucosyllactose (2′-FL) and Lacto-N-Neotetraose (LNnT) in Infant Formula. Nutrients, 10(1161).

Wallingford, J.C., Neve Myers, P., & Barber, C.M. (2022). Effects of addition of 2-fucosyllactose to infant formula on growth and specific pathways of utilization by Bifidobacterium in healthy term

Infants. Frontiers in Nutrition, 9.

Wiciński, M., Sawicka, E., Gębalski, J., Kubiak, K., & Malinowski, B. (2020). Human Milk Oligosaccharides: Health Benefits, Potential Applications in Infant Formulas, and Pharmacology. Nutrients, 12(1):266.

Zeuner, B., Teze, D., Muschiol, J., & Meyer, A.S. (2019). Synthesis of Human Milk Oligosaccharides: Protein Engineering Strategies for Improved Enzymatic Transglycosylation. Molecules, 24(11):2033.

Zhang, A., Sun, L., Bai, Y., Yu, H., McArther, J.B., Chen, X., & Atsumi, S. (2021). Microbial production of human milk oligosaccharide lactodifucotetraose. Metabolic Engineering, 66:12-20.

Zhang, S., Li, T., Xie, J., Zhang, D., Pi, C., Zhou, L., & Yang, W. (2021). Gold standard for nutrition: a review of human milk oligosaccharide and its effects on infant gut microbiota. Microbial Cell Factories, 20(1):108.