How a component of breast milk can help adults with gut health issues

December 15, 2020 5 min read

How a component of breast milk can help adults with gut health issues - Layer Origin Nutrition

The first time people hear the acronym HMO they might think of the health insurance plans that were popularized in the 90s. 

HMO vs PPO ring a bell? But the three letters HMO also stand for something else. Something much more exciting, in fact. 

Human milk oligosaccharides (HMOs) are complex indigestible sugars naturally present in breast milk. In fact, HMO is the third most common solid in breast milk, after lactose and fat. However, most people have never heard of HMO. 

Black graphic with yellow text and white milk splash image.

Human milk oligosaccharides escape digestion, allowing them to reach the colon where they feed beneficial bacteria. So HMO is a prebiotic that feeds probiotic bacteria. It has also been shown to ward off pathogens. 

The benefits of HMOs for infants are well documented and there's recent research indicating HMOs are also very beneficial for adults. 

Within the last 10 years, interest in HMOs began to rise, especially in the infant formula industry, where companies are striving to make a synthetic milk (formula) that is as close to genuine breast milk as possible. By 2016, most major baby formula producers were putting HMOs into their formulas and they weren't hiding it. They prominently placed the acronym right on the front of the jars and bottles. 

Graphic showing three baby formula containers with HMO acronym on them.

As HMO entered the baby formula industry because of its immense benefits, the next logical question was how it could be offered to adults with current stomach or immunity issues, in particular. 

HMOs help shape a healthy microbiota

A healthy gut microbiome has a huge impact on human health. Besides supporting digestive system, the gut microbiome is also involved in immune health and cognitive development1.

Blue graphic showing gut bacteria with the world "microbiome"

The introduction of beneficial bacteria, such as Bifidobacteria and Lactobacilli, in the form of probiotics can help build a healthy and diverse microbiome. HMOs function as a prebiotic fiber, with the majority of them reaching the large intestine undigested. There, HMOs feed the beneficial bacteria and hinder the colonization of harmful bacteria. 

The key word in that last paragraph? Fiber. 

Yes, fiber. 

Fiber has been done SO wrong in our cultural zeitgeist. We think of fiber as the orange drink that grandma sips to help her constipation. When in reality, fiber is so much more. Fiber is found in avocados (whether it's spread on your toast, or not). Fiber is in fruit and vegetables. The key is your gut thrives on fiber. 

Orange graphic with green text that says "Fiber is more than just Metamucil"

One hundred healthy adults (average age of 36) participated in a clinical study performed by scientists from Denmark and Switzerland.2 They were randomly assigned to one of ten groups and each consumed HMOs, 2′-O-fucosyllactose (2′-FL) or lacto-N-neotetraose (LNnT), at 5, 10 or 20 g or 2 g of glucose as the control group each day for two weeks. The result showed HMO supplementation specifically boosted Bifidobacteria levels and reduced Firmicutes and Proteobacteria levels in the human body.

Pink graphic with green arrows about gut bacteria.

Bifidobacteria have long been regarded as beneficial bacteria in the human gut. Low levels of Bifidobacteria have been reported in people with obesity and diabetes3, in individuals taking antibiotics, and in patients suffering from irritable bowel syndrome or inflammatory bowel disease.

Therefore, using HMOs as a supplement may be a good strategy to promote the growth of the beneficial Bifidobacteria and improve overall gut health.

HMOs protect you from harmful pathogens, infections, & bacterial toxins 

Pathogens include viruses, bacteria, fungi, and parasites that invade the body and cause health issues. Many pathogens recognize the carbohydrate structure on the surface of cells as a receptor. Luckily, some HMOs have the same structures as those receptors on the surface of cells.

By binding with the bacteria, viruses, and even parasites, HMOs may function as inhibitors of infection. 

Blue and pink graphic showing pathogens.

Research has suggested that HMOs have direct effects on intestinal epithelial structure and function, and can interfere with the adhesion of infectious bacteria such as:

  • Campylobacter jejuni
  • Escherichia coli
  • Vibrio cholerae
  • Salmonella fyris
  • Helicobacter pylori
  • Protozoan parasites such as Entamoeba histolytica

Enteric infections are a major health challenge for people of all ages as well as animals raised for food, such as chickens and pigs. Therefore, HMOs may be used as protective agents against enteric infection for a wide range of species. Besides interfering with pathogens, some HMOs contain sialic acid, which can also bind with toxins. These sialylated oligosaccharides seem to behave as potential inhibitors against the toxins produced by harmful bacteria. 

HMOs alleviate symptoms of allergic diseases 

Allergic diseases are increasing worldwide with unprecedented complexity and severity. An allergy could emanate from something you eat, inhale into your lungs, inject into your body, or something you touch. In severe cases, it can cause rashes, hives, low blood pressure, breathing trouble, asthma attacks and even death. Allergies are estimated to affect the lives of almost 1 billion people worldwide and are the sixth leading cause of chronic illness in the U.S. HMOs are recognized as having a prebiotic function and supporting the immune system, which also suggests they may have therapeutic potential in managing allergic diseases.

Graphic of boxer punching next to a flower.

One animal study showed oral treatment with the HMOs 2’-fucosyllactose and 6’-sialyllactose (2'-FL and 6′-SL) alleviated food allergy symptoms including diarrhea and hypothermia5.

Researchers suggest that 2’-FL and 6′-SL reduce the symptoms of food allergies through induction of two types of immune cells, which are IL-10(+) T regulatory cells and mast cells.

T regulatory cells control the immune response to internal and foreign particles (antigens) and help prevent autoimmune disease. Mast cells play an important role in many inflammatory actions including host defense to parasitic infection and in allergic reactions.

Blue graphic with orange arch discussing HMOs

Further studies showed 2’-FL and 6′-SL regulated human epithelial cell responses related to allergic disease6. Particularly, 6′-SL may have additional benefits by inhibiting chemokine release and other inflammatory signals, which could alleviate symptoms of food allergies by inhibiting the influx of inflammatory cells to the intestine.

HMOs help with gut motility disorders and gut pain 

The role of HMOs as a modulator of intestinal motility also draws lots of interest. Many studies support the idea that fucosylated HMOs might be useful as therapeutic or preventative adjuncts in gut motility disorders and gut pain, and possibly also have beneficial central nervous system effects.7

Is it safe for adults to have HMOs as a supplement?

Just as HMO is one of the most popular components added into infant formula, and considered safe for babies, it is also safe for adults. Research conducted in Europe showed daily intake up to 20g of 2′-FL or LNnT among healthy adults was perfectly safe and well tolerated.  

Altogether, supplementing the diet with HMOs is a valuable and safe strategy to influence the gut microbiota.

HMOs also have the capacity to modulate immune function and the gut barrier, supporting the potential of HMOs to provide plentiful health benefits in adults.  


  1. Bode, Lars. "The functional biology of human milk oligosaccharides." Early human development 91.11 (2015): 619-622. 
  1. Elison, Emma, et al. "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 (2016): 1356-1368. 
  1. Schwiertz, Andreas, et al. "Microbiota and SCFA in lean and overweight healthy subjects." Obesity 18.1 (2010): 190-195. 
  1. Coppa, Giovanni V., et al. "Human milk oligosaccharides inhibit the adhesion to Caco-2 cells of diarrheal pathogens: Escherichia coli, Vibrio cholerae, and Salmonella fyris." Pediatric research 59.3 (2006): 377-382. 
  1. CastilloCourtade, L., et al. "Attenuation of food allergy symptoms following treatment with human milk oligosaccharides in a mouse model." Allergy 70.9 (2015): 1091-1102. 
  1. Zehra, Sehrish, et al. "Human milk oligosaccharides attenuate antigen–antibody complex induced chemokine release from human intestinal epithelial cell lines." Journal of food science83.2 (2018): 499-508. 
  1. Adams, Clifford A., and Bettina Gutiérrez. "The benefits of human milk oligosaccharides in adult nutrition." Nutrafoods 17 (2018): 169-173.

Interested in learning more about Human Milk Oligosaccharides?

Sign up for the free Layer Origin Nutrition newsletter.

Leave a comment


How Can the Gut Microbiome Help Reverse Aging
How Can the Gut Microbiome Help Reverse Aging?

June 09, 2024 8 min read

Aging is a fact of life, even if we don't like to admit it. In this article, we'll delve into 4 of the tell-tale signs of aging to help us better understand the process and explore if it can be reversed.
Read More
New Study Links Gut Microbiome Composition With Your Social Decision-Making
New Study Links Gut Microbiome Composition With Your Social Decision-Making

June 01, 2024 7 min read

Read More
Layer Orignin - The Health Benefits of Urolithin A - A Postbiotic Produced In Your Gut - for Bone, Muscle, Brain Health, and Aging
The Health Benefits of Urolithin A - A Postbiotic Produced In Your Gut - for Bone, Muscle, Brain Health, and Aging

May 19, 2024 7 min read

The human gut microbiome is a myriad of microbes working together in harmony, but it's also the hub of numerous biological transactions. The conversion of the polyphenols, ellagic acid and ellagitannins, into urolithin A is an interesting and hot topic. Urolithin A has been earmarked for its anti-aging potential, and in this article, we explore its benefits for bone, muscle, and brain health.
Read More