What have Human Milk Oligosaccharides Got to do With Your Baby?

Human milk oligosaccharides are the third most abundant component of breastmilk and perform important functions in the infant!
a mother holding her baby feeding him a bottle

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Disclaimer: this post was sponsored by Abbott Nutrition. As always, all thoughts and opinions are our own.  

We recently made a statement in our Instagram stories about how we support all parents feeding their babies, regardless of whether it’s by breastmilk or formula… or both!  

Despite our best efforts to not shame anyone for their choices, some took a bit of offense to this statement we included: 

“We recognize that breastmilk is unparalleled in its ability to provide the safest food for your baby and the most precisely matched for your baby’s unique needs.” 

While we understand this may seem as though we’re dissing formula, we’re not!  

In developed countries, health outcomes of formula-fed babies are certainly positive. 

BUT we want to support the best outcomes for all babies which means we want ALL babies to get the very best they can.  

And we can do that by upholding breastmilk as the gold standard.  

Because when we uphold breastmilk, then the formula companies are going to do the research to keep improving formula to make it as close a match as possible to breastmilk! 

Before the 19th century, little was known about infant nutrition and human milk substitutes were not providing the adequate nutrition to these babies, resulting in negative health outcomes. Fortunately, research about infant’s nutritional needs and development increased and lead to innovations throughout the years. Take a look at these formula innovations… 

Whey Protein: 

  • There are two main types of milk proteins: whey and casein. Breastmilk is more whey dominant while cow’s milk is more casein dominant. Formula companies started to add more whey into their formulation to better mimic breastmilk. 

Omega 3, DHA in particular: 

  • DHA (docosahexaenoic acid), is one type that’s pretty important for the physical development of the brain, nerves, and eyes! Studies for the benefit of adding DHA to infant formula have mixed results, which is why DHA is not mandatory in formulas in North America. Since February 2020, infant formula sold in Europe must contain at least 20-50mg of DHA per 100 calories. Many formulations in Canada include DHA, to give parents the choice.  


  • Lutein is both an antioxidant and a structural component of the eyes and brain. Levels of lutein in breastmilk vary depending on mama’s diet. Lutein may play a role in preventing oxidative stress in the newborn but research in this area is limited. Until they start solid foods, babies who are not breastfed can only get lutein from an infant formula that is supplemented with lutein. 
  • Vitamin E: 
  • This fat-soluble vitamin is another antioxidant that keeps oxidative stress at bay.  
  • Nucleotides: 


  • Probiotics are specific strains of living micro-organisms that have been shown in research to provide a benefit to the host, in this case: human babies! In the same way that different drugs help alleviate different symptoms, each probiotic strain will provide its own unique benefit. In general, the benefits only continue as long as the probiotics continue to be consumed. Human milk contains a wide variety of probiotic cultures, transferred from the mothers’ own gut microbiota.  
  • Research is ongoing for the possible benefit of preventing allergies, urinary tract infections, and relieving colic.  

The research on the benefits of many of these formula ingredients is mixed, which is why they are optional for companies to include, not mandatory.  

… but up until now a BIG component of breastmilk had not been replicated in formula. 

Excluding water, can you guess which of these makes up the biggest component of breastmilk? 

  1. Proteins 
  2. Carbohydrates 
  3. Fats 
  4. Human Milk Oligosaccharides 

Carbohydrates (mainly lactose) are the most abundant nutrient in breastmilk, followed by fat, and then…. Human milk oligosaccharides1,2

An infographic of a chart of the components of breastmilk pictured as a breast. Protein: 8-12g/L, Human Milk Oligosaccharides: 5-15g/L, Lipid : 40g/L, and Lactose: 70g/L.

Yup, it’s true! There’s more of this strange thing you’ve likely never heard of before than there is PROTEIN! 

We know protein is super important for baby so logically, these human milk oligosaccharides have got to be too, right? 

Which is why scientists have been very curious about the role they play in baby’s health.  

Okay, now that we’ve piqued your interest, let’s take a look at human milk oligosaccharides and why we’re excited that you can now find 2’-FL in a Canadian infant formula! 

What are human milk oligosaccharides? 

While this might be the first time you’re hearing the term, “Human milk oligosaccharides”, research in this area actually originated at the end of the 19th century. So, basically a long time ago. What exactly are these compounds? Let us explain. 

Human milk oligosaccharides (let’s go with HMOs from now on) are short chain carbohydrates that a lactating woman produces in her milk-producing glands and secretes into her breastmilk that are then transferred to her baby.  

These little carbs do not get digested but pass through the digestive system to the large intestine where they selectively promote the growth of beneficial bacteria in the baby’s gut. In breastfed babies, these good bacteria help support the developing immune and digestive systems and may help protect babies from infections. Think of them as little “guards” or a decoy against potential pathogens in your baby’s gut.  

In short? HMOs are prebiotics that help promote the breastfed baby’s gut and immune health! 

Scientists have identified over 100 different types of HMOs, but the most abundant in the milk of most lactating womxn is 2’-Fucosyllactose (2’-FL) by a long shot.  

Why should I care about HMOs? 

Fast forward to 2021, a host of scientists worldwide have accumulated a body of evidence that now confirms HMOs impart a growing number of benefits to breastfed infants.  

Decreased inflammatory immune response  

HMOs have a unique ability to directly and indirectly impact an infant’s immune system. As mentioned earlier, HMOs act like a decoy. When pathogenic bacteria enter the gut, HMOs bind to them, preventing them from being absorbed by the baby and thereby help strengthen the baby’s immunity. Additionally, we see that when HMOs are fermented (which is what happens in the colon), their by-product, short chain fatty acids (SCFA), improves intestinal barrier function, lowers the pH in the colon, and has well-established anti-inflammatory properties. 

Fewer respiratory infections (such as bronchitis) 

HMOs, among several other components in breast milk may influence the nasopharyngeal (that’s the part of the throat behind the nose!) microbiota composition—which may contribute to the protective effect of breastfeeding on decreased respiratory infections.  

Less eczema 

Infant eczema is multifactorial, however in one study of 266 infants followed for 5 years, scientists observed that infants born to folx who secreted 2’-FL in their breastmilk had lower incidence of IgE-mediated (allergy-related) eczema. 

A flatlay of different foods and objects that represent different things that can help support baby's immune health: fibrous foods, water, breastfeeding, teether toys, Vitamin D.

Similac Pro-Advance® 

Up until now, we’ve offered you dietitian-approved information when it comes to starting your baby on solid food. We’ve also touched on our breastfeeding experiences with each of our children, like when Nita struggled with Renaud’s Syndrome and Jessica was struck with bouts of mastitis. But, what about formula? Well, we’re #hereforit. 

From the beginning, our manifesto has been simple. It’s to help caregivers feel confident about feeding their baby. We’re here to help you make informed and supported decisions. Over on our Instagram community, we’ve spent months talking to you and listening to your stories. We realize that many women are either unable to or choose not to breastfeed for a multitude of complex reasons.   

For this reason, we want to help parents navigate the world of infant formula. It’s vast. We know.  

For infants who are not breastfed, formula will play a critical role in their nutritional status and overall development. For many, it’s what they feed on exclusively for 6 months.  

It isn’t new news, but Similac® has gone beyond DHA, researching other components that are concentrated in the brain and eyes, such as lutein and vitamin E. These ingredients are included in several of their formulations.  But, there’s been a change in their game! Recently (like…really recent), Similac® created a new formula that includes 2’-FL Oligosaccharide, an ingredient with an identical structure to 2’-FL found in breastmilk (2’FL HMO). Say WHAT? 

Yes, you read that right. Over the last two decades or so, scientists have not only studied HMOs, like 2’-FL, but they have also been successful at creating a molecule with the exact same structure as 2’-FL found in breastmilk. Inspired by breastmilk, they wanted to see if adding this ingredient to infant formula would confer some of the immunological benefits attributed to 2’-FL HMO to the formula-fed baby. So far, the research looks promising from our perspective.  

Think about it: 70% of the immune system is found in the gut which means that nourishing the gut and the good bacteria that live there is very important. 

HMOs, like 2’-FL, are prebiotics found in breast milk that help strengthen the immune and digestive systems of breastfed babies.  All along, breastfed babies receive these (a lot of these!).   

With this new innovation, formula-fed babies can get 2’-FL, an ingredient with the exact same structure as 2’-FL found in breast milk. 

This truly is ground-breaking for the formula industry – while breastmilk will always be the gold standard, scientific breakthroughs and technology also mean that formula-fed babies can potentially benefit from some new ingredients modeled after components that were previously only available to breastfed babies.  

A woman's hand is holding a bottle of ready to feed Similac Pro Advance.

How does 2’-FL Oligosaccharide shape up in research? 

Okay okay, you get it. Formula technology is very advanced and fancy now. We’ve got a solid understanding of HMOs and that 2’-FL has been synthesized to mimic the same chemical structure to that which is found in breastmilk.  

But, what actually happens when we add it into formula? 

Pretty fascinating things.  

A recent Journal of Nutrition study showed that babies fed Similac® with 2’-FL had levels of immune system markers that were much closer to breastfed babies. In the study, the blood of 6 week old babies was drawn to look at specific immune markers. The babies were randomly fed 1 of 3 formulas: The control group received a formula not supplemented with 2’-FL while the each of the other two groups received a formula supplemented with different amounts of 2’-FL.  All of these babies were compared to a group that was exclusively breast fed.  

Fast forward 4 months, researchers saw that the babies fed the control formula (no 2’-FL) had higher inflammatory cytokines (markers of inflammation). Meanwhile the babies who consumed the formulas with 2’-FL had 29-83% lower concentrations of plasma inflammatory cytokines compared to the control group, closer to those of the breastfed reference group. 

When not to switch 

If you’re reading this and you’re super excited to switch formula…..Wait a minute. Any time you change formula, you want to think things through thoroughly. 

Similac Pro-Advance®, is a cow’s milk based formula like many others, and is not suitable for babies that have:  

  • true (congenital) lactose intolerance  
  • cow’s milk protein allergy 
  • galactosemia 

On a final note 

This is the first time we’ve made space for formula-related content on our blog. But, it won’t be the last. We’re hoping to spend a bit more time plugging away, learning, and putting together information that serves you.  

If and when you do shop for formula, you may want to keep this blog post handy to remind you of the potential benefits of synthesized 2’-FL. It’s pretty darn neat that scientists have been able to propel formula technology to include this ingredient.  

And, if you’re a breastfeeding parent, we hope the geeky science talk was up your alley!  

† Not derived from human milk; identical structure to 2’-FL found in breast milk 


  1. Jantscher-Krenn E, Bode L. Human milk oligosaccharides and their potential benefits for the breast-fed neonate. Minerva Pediatr 2012;64:83-99.
  2. Zivkovic AM, German JB, Lebrilla CB et al. Human milk glycobiome and its impact on the infant gastrointestinal microbiota. Proc Natl Acad Sci 2011;108(Suppl. 1):4653-8.  

Additional citations: 

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3406618/ 
  2. https://www.atsjournals.org/doi/full/10.1164/rccm.201401-0073OC 
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6036705/#B146  
  4. https://link.springer.com/article/10.1007/s00394-016-1180-6  

jess and nita, registered dietitians
Meet Jess and Nita

Hi! We’re both Dietitians & boy mamas! We’re here to help you confidently raise kids who will grow up to be lifelong Happy Healthy Eaters. Dig into our site for kid-tested recipes & feeding tips. 

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