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What Are Human Milk Oligosaccharides (HMOs) in Infant Formula?

Medically Reviewed by May Zhu, RDN | Published January 16, 2025

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As parents become increasingly focused on improving their baby's nutrition, you may have heard about Human Milk Oligosaccharides (HMOs) as a key ingredient in some infant formulas.

These naturally occurring compounds in breast milk are gaining attention for their role in supporting a baby’s gut health, immunity, and overall development.

But what exactly are HMOs, and how do they work in infant formula? Let’s dive in.

What Are HMOs?

Human Milk Oligosaccharides (HMOs) are complex carbohydrates that are abundant in human breast milk, with over 200 distinct types identified.

HMOs are the third most abundant solid component in breast milk after lactose and fats (Bode, 2015). They play a unique and vital role in a baby’s health, especially during the early months of life when their immune system and gut microbiome are still developing.

Interestingly, HMOs are indigestible by the baby but act as prebiotics, feeding beneficial bacteria in the gut.

By promoting the growth of good bacteria like Bifidobacterium infantis, HMOs help establish a healthy microbiome that supports digestion, immunity, and protection against harmful pathogens.

How Do HMOs Work?

HMOs serve several critical functions in infant health:

Promote Gut Health

  • HMOs feed beneficial bacteria in the gut, creating a balanced microbiome. A healthy gut microbiome plays a role in digestion, nutrient absorption, and immune system regulation.

Support Immune Function

  • Approximately 70% of the immune system resides in the gut, and HMOs contribute by reducing inflammation and blocking harmful bacteria and viruses from attaching to the gut lining. This creates a protective barrier that lowers the risk of infections (Donovan & Comstock, 2016).

Aid Brain Development

  • Emerging research suggests that HMOs may support cognitive development through their interactions with gut bacteria and the gut-brain axis, though more studies are needed to confirm these effects.

Protect Against Allergies

  • Studies indicate that HMOs can modulate the immune response and may help reduce the risk of certain allergic conditions like eczema and food allergies (Berger et al., 2020).

HMOs in Infant Formula

Because HMOs are a natural component of breast milk, infant formula manufacturers have worked to replicate their benefits.

Advances in food science have made it possible to include synthetic HMOs, such as 2’-Fucosyllactose (2’-FL) and Lacto-N-neotetraose (LNnT), in some formulas.

Can babies and kids with milk allergies consume HMOs? Find out what our nutrition scientist says here.

These HMOs are bio-identical to those found in breast milk and are generally recognized as safe (EFSA, 2019).

Research has shown that HMO-enriched formulas can support the gut microbiome, immunity, and overall health in ways similar to breast milk Puccio et al., 2017).

Why Choose a Supplement or Formula with HMOs?

If breastfeeding is not an option or needs to be supplemented, choosing a supplement or formula with HMOs can provide added support for your baby’s gut and immune health. HMOs in formula offer closer replication of breast milk's natural benefits, giving your baby the foundation they need to thrive.

Summary

Human Milk Oligosaccharides (HMOs) are naturally occurring sugars in breast milk that support a baby’s gut and immune health. HMOs serve as prebiotics, such as those found in Beginbaby Prebiotic + Probiotic to support better digestion and less fussiness in babies. 

View Citation

  • Bode, L. (2015). The functional biology of human milk oligosaccharides. Early Human Development, 91(11), 619–622. https://doi.org/10.1016/j.earlhumdev.2015.09.001
  • Donovan, S. M., & Comstock, S. S. (2016). Human milk oligosaccharides influence neonatal mucosal and systemic immunity. Annals of Nutrition and Metabolism, 69(Suppl 2), 42-51. https://doi.org/10.1159/000452818
  • Berger, P. K., Plows, J. F., Jones, R. B., & Alderete, T. L. (2020). Human milk oligosaccharides: Prebiotics, infant health outcomes, and the gut microbiota. Advances in Nutrition, 11(3), 497-502. https://doi.org/10.1093/advances/nmz110
  • Puccio, G., Alliet, P., Cajozzo, C., Janssens, E., Corsello, G., Sprenger, N., & Steenhout, P. (2017). Effects of infant formula with human milk oligosaccharides on growth and morbidity: A randomized multicenter trial. Journal of Pediatric Gastroenterology and Nutrition, 64(4), 624–631. https://doi.org/10.1097/MPG.0000000000001520
  • European Food Safety Authority (EFSA). (2019). Safety of 2′-fucosyllactose as a novel food pursuant to Regulation (EU) 2015/2283. EFSA Journal, 17(7), e05720. https://doi.org/10.2903/j.efsa.2019.5720