Human Milk Oligosaccharides: The Ultimate Guide to HMOs for Better Gut Health

You can use this page as your comprehensive guide for everything you need to know about Human Milk Oligosaccharides (HMOs) and how to harness their power for better gut health, immune health, and cognitive function. 


    Human Milk Oligosaccharides (aka HMOs) are not well known among the general public. But you should expect to hear more about them in the near future. While this component of human breast milk has been looked at for more than a hundred years by scientists, the application seemed limited to infants for most of the last century. 

    However, as you may have recently learned, HMOs are now being produced specifically for adults, in formulations that are proven to provide support for gut health problems, the immune system, and cognitive function.1

    This is big. 

    What percentage of breast milk is made up of HMO?

    Typically, human breast milk exhibits this compositional profile

    • 70 g/l of Lactose 
    • 40 g/l of Lipids 
    • 5 to 15 g/l of HMOs
    • 8g/l of Proteins 

    The lactose, lids, and proteins are nutritive - providing nourishment to the recipient, whereas the HMOs are bioactive but non-nutritive, as they are indigestible, but do support the microbiota. 

    Breakdown of breast milk components

    The rise in probiotic bacteria supplements2 was an important advancement in health and nutritionsince 2000, but more recently, the awareness of prebiotic bacteria has grown. HMO is perhaps the least known, but most effective prebiotic on the planet. 

    Other prebiotic bacteria exist such as FOS, GOS, XOS, et al. but HMO has the greatest upside. For years, HMO was not really an option for adults. Access to HMO was limited to infants via breastfeeding. But that didn't stop scientific researchers from experimenting.Could there be a way to create a bio-identical HMO that would benefit adults (and kids and teens) the way the HMO in breast milk benefits infants?

    After decades of research, the answer was ... yes! 

    Prebiotic bacteria in blue text over yellow bacteria graphicHMO began appearing in big-brand infant formula circa 2016with brands like Similac and Enfamil suddenly touting the presence of the gut, immune & brain-boosting ingredient in their products. So how did it happen?

    After years of trial and error, scientists were able to take highly purified lactose, precisely ferment it (similar to the way in which wine is fermented), and then purify it further, resulting in an end product that was bio-identical to the HMO found in breastmilk. For example, PureHMO™ Prebiotic from Layer Origin Nutrition is 98% pure 2'-Fucosyllactose (2'-FL). That variety of HMO (2'-FL) is usually the most prevalent variety of HMO in breast milk. In all, there are between 130-200 varieties of human milk oligosaccharides.6

    There's still more research to be done on HMOs but it's clear that they are helping thousands of adults right now and have abundant potential for future health and nutrition outcomes. 

    The following list is a collection of topics regarding HMOs that are filtered into various questions and answers. 

    What are Human Milk Oligosaccharides?

    Human Milk Oligosaccharides, "HMOs" for short, are a component of human breast milk. They are a class of molecules that are actually indigestible yet play a hugely important role in the composition of the milk.7

    "What are HMOs?" infographic in navy blue and greyScientists first identified a large fraction of non-lactose carbohydrate, which they called gynolactose, in the 1930s.Its role remained unknown until the 1950s, when it was identified as the same entity as the bifidus factor.Chemical and biological breakthroughs later uncovered hundreds of these factors, of different lengths, which appeared to be there to feed the baby’s gut bacteria. This realization inspired the field, and research into the newly renamed 'human milk oligosaccharides' quickly advanced. By 2000, researchers discovered more than 100 HMOs, which provide food for Bifidobacterium bifidus and other bacteria species. The prebiotic effect of HMOs was proven, but it wasn’t the full story.1

    By 2016 HMOs were in most name-brand baby formulas. Over the next five years they would begin to appear in supplements meant specifically for adults. 

    Still confused? 

    This short video explains HMOs quite well.

    What is the difference between HMO and colostrum?

    Colostrum is the "first milk" or nutrient-rich "pre-milk" from mothers, which can feed babies in the first few days after they are born. So it's a fluid from the breast which is very nutritious and contains high levels of antibodies - as proteins that fight infections and bacteria. Human Milk Oligosaccharides are different. HMOs  are the oligosaccharides in actual breast milk and are produced during the whole lactation period.9

    [RELATED POST: Where can you get HMOs for adults? (Human Milk Oligosaccharides)]

    What is the difference between FOS, XOS, GOS versus HMO?

    FOS, XOS, and GOS are oligosaccharides that usually contain only repeating sugar units such as fructose, xylose, and galactose. These are essentially the "old guard" when it comes to probiotics. HMOs on the other hand, also contain sugar units but in addition, they contain other functional groups like acetylglucosamine.10

    HMOs versus GOS/FOS pink infographicWho should consider taking HMO?

    People who have been diagnosed with IBS or another diagnosable gut health condition should seriously consider taking a human milk oligosaccharide supplement.11Anyone who feels like they have the symptoms of IBS but who has not been diagnosed should also think about taking an HMO supplement.12

    Even people with zero gut health issues may benefit from an HMO product because of the ancillary benefits to the immune system and cognitive function.12

    Man grabbing stomach in pain with text "Should you try HMOs?"So, in theory, anyone could take an HMO supplement, but the primary use case is for those who are experiencing gut health issues. 

    Similar to probiotic supplements, many people may want to take a prebiotic as a bodily insurance policy of sorts, even if they currently have no obvious gut health problems. 

    It's widely known in scientific circles (but not by the average person) that probiotics and probiotics work in concert with each other. Prebiotics are the "food" for probiotics. It's important to have both and have them working together.13

    How is HMO produced?

    Traditional human milk oligosaccharides are naturally present in human breast milk. The next generation of HMOs begin with high purity lactose that's fermented via bacteria or yeast (similar to the fermentation process for wine). HMOs go through many steps of purification to remove all other ingredients or bacteria, resulting in a final product that is more than 98% pure according to laboratory tests (the 98% purity level refers to Layer Origin Nutrition's PureHMO™ products). 

    The oligosaccharides in cow's milk are structurally similar to those in human milk, but their concentration is much lower. Cow's milk is already the most common milk used for infant formula in the U.S., so oligosaccharides extracted from it would be expected to be safe for human consumption. Researchers utilized filtration techniques to remove most of the lactose and salts from cow milk and increase the concentration of oligosaccharides. Oligosaccharides can be synthesized through a series of chemical reactions, which is another approach that researchers have been pursuing. 

    Production factory with text "Made in the USA in an FDA Certified Facility"Some companies and researchers use genetically engineered microbes to produce HMOs. They genetically engineer microbes to introduce the enzymes necessary to produce HMOs. They use either the bacteria Escherichia coli, which is often used to produce proteins and metabolites, or the yeast Saccharomyces cerevisiae, used in baking, winemaking and brewing.

    They use those two microorganisms to produce human milk oligosaccharides, typically focusing on production of 2’-Fucosyllactose (2-FL), which is one of the most abundant HMOs in human milk. Scientists are very confident that this 2-FL is the same as 2-FL in human milk. They can use genetically engineered E. coli to make up to 2-3 gm/L of 2-FL in the medium, similar to its levels in milk. Even though the E. coli strain they have used is very different from the ones that cause food disease, due to negative public perceptions about E. coli, they have switched to using yeast. People drink wine and beer or eat bread everyday so they perceive that this strain is safer, so researchers learned how to make 2-FL in yeast. Researchers are still optimizing 2-FL production in yeast to produce similar levels to that in E. coli.

    What is the best dosage amount of HMO per day?

    In general, Layer Origin Nutrition recommends that adults take 2000mg of HMO per day. The serving should be consumed at approximately the same time each day. However, the time of day does not particularly matter. HMO is indigestible so it can be taken with or without food. People who are taking HMO capsules typically do so with a glass of water. People who take HMO powder can do so with any beverage. Joel Greene, author of The Immunity Code, and a primary proponent of HMOs, recommends taking HMO as part of a smoothie

    For example, Layer Origin Nutrition's PureHMO™ Prebiotic capsules have 1300mg HMO per serving (two capsules). For best results, Layer Origin recommends taking two capsules per day with four ounces of water for the first three to five days, prior to increasing to three capsules per day thereafter. 

    Mint green background with text "2000mg of HMO per day" But Layer Origin Nutrition's PureHMO™ Prebiotic + Probiotic capsules contain just 1000mg HMO per serving (two capsules). So to get 2000mg of HMO per day, one would need to take four capsules. This product also contains 100 Billion CFU of probiotics per serving. 

    Layer Origin Nutrition's PureHMO™ Prebiotic powder contains 1950mg of HMO per scoop. So someone taking the power product would only need to take about one scoop per day. As fitness guru Joey Thurman could attest on his Fad or Future podcast, it is a very small scoop. 

    Do Layer Origin Nutrition PureHMO™ Prebiotic capsules contain anything else besides 2'-FL ?

    Yes - in addition to 2'-Fucosyllactose, PureHMO™ Prebiotic capsules contain other ingredients, which make up the vegetable-based capsule. Those ingredients are hydroxpropyl methyl cellulose, vegetable magnesium stearate, and silica. 

    PureHMO™ Prebiotic capsules bottle ingredients labelAre Human Milk Oligosaccharides (HMOs) made from human milk?

    No. The products designed for adults DO NOT come from human milk. For example, Layer Origin Nutrition's entire line of HMO supplements are derived from precisely fermented and highly purified lactose. They have zero connection to human milk other than being designed to replicate one of the many HMOs inside human milk. However, the HMOs found inside human milk are of course, a part of human milk, so yes. 

    It might be easier to think of it like Gatorade. Yes, the sports drink. Imagine if I asked you whether Gatorade is made from human sweat. Let's ask it: Is Gatorade made from human sweat? The answer of course, is "no". However, Gatorade does contain electrolytes and electrolytes can be found in human sweat.

    Vintage Gatorade advertisement featuring Vince Carter. Gatorade was created to mimic exactly what is lost when humans sweat so humans can drink it and replenish those missing electrolytes. So in essence, Gatorade is based on human sweat, contains some of the same components, and is designed to replace human sweat. However, Gatorade itself, does NOT contain any human sweat. 

    Hopefully that makes sense. 

    Can you take human milk oligosaccharides if you are lactose intolerant? 

    The short answer is, yes. However, there is some background information that you should know.

    Lactose IntoleranceLactose intolerance is a digestive disorder caused by the inability to digest lactose, the main carbohydrate in dairy products. People with lactose intolerance don't make enough of the enzyme lactase, which is needed to digest lactose (from healthline). In fact, research has shown that many people with lactose intolerance can tolerate up to 12 grams of lactose in one sitting, which is approximately the amount in one cup (230 ml) of milk (Healthline). We know that 230 ml of milk contains 11.04 g of lactose. For example, Layer Origin Nutrition recommends a total serving size of 2g of HMO, therefore, even people with lactose intolerance can take their HMO capsules without any problems.
    Female doctor holding sign that says "Lactose Intolerance"
    Milk allergy: Some people are allergic to milk and it's milk proteins that are the component causing allergies. Although Layer Origin Nutrition tested its HMO and found zero detectable milk proteins in its HMO they still put the following statement on their bottles to be cautious: "Contains: trace amount of lactose (milk). Third-party Lab (FARRP) validated PureHMO™ does not contain intact milk proteins. However, we recommend people with a milk allergy proceed with physician’s approval."

    Does hot coffee kill prebiotic and probiotic bacteria?

    No - in fact many people add Layer Origin Nutrition's PureHMO™ Prebiotic powder to their coffee in the morning by just stirring it into their mug. The powder is virtually tasteless and mixes well with various liquid so it works quite well. The prebiotic bacteria is not compromised by the high temperature. The same goes for probiotics. Layer Origin Nutrition's PureHMO™ Prebiotic + Probiotic capsules could also be taken with hot coffee in theory, although most people prefer to just swallow them with a glass of water. 

    Hot coffee in white mug with text "Can probiotics & prebiotics survive hot coffee?"Are there any nutrition experts who recommend that adults take HMOs?

    Yes - Ben Greenfield, Joel Greene, and Joey Thurman have all spoke about the vast array of benefits associated with supplementing with human milk oligosaccharides. Greenfield had Greene on his podcast as a guest in July 2020 to discuss HMOs.

    Ben Greenfield without a shirt one in front of green background Then, Greenfield hosted Greene again on The Ben Greenfield podcast in January 2021. On both occasions Greene evangelized HMOs, discussing the research behind their efficacy, his approach to taking them, and how people used to try to get HMOs into their system prior to supplements like those made by Layer Origin Nutrition

    Celebrity trainer and food and nutrition expert, Joey Thurman (CPT, FNS, CES) has been taking PureHMO™ Prebiotic powder from Layer Origin Nutrition and recently spoke about his belief in the product on his podcast, Fad or Future. 

    Joey Thurman without a shirt on in front of blue backgroundAre there any doctors who recommend that adults take HMOs?

    Yes - Dr. Rhonda Patrick (PhD) and Dr. Will Bulsiewicz (MD, MSCI) both recommend human milk oligosaccharides for adults. Patrick talked about the amazing power of HMOs during her interview with Joe Rogan. Patrick has a PhD in biology and more than 349,000 people subscriber to her YouTube channel

    Bulsiewicz discussed HMOs during his interview with Rich Roll. Bulsiewicz is known as "The Gut Health MD" and has a large following on Instagram. He may be best known for his book "Fiber Fueled".  

    Are human milk oligosaccharides safe?

    Yes! Our main goals are health and safety.

    PureHMO™ Prebiotic is third-party lab-tested and produced in an FDA-registered facility with GMP certification. In numerous clinical studies conducted at top universities and laboratories across the world, literally thousands of adults and babies have taken HMOs, at doses even greater than the 2000mg per day recommended by Layer Origin Nutrition. There were no problems with regard to safety or severe side effects. 

    What is 2'-Fucosyllactose?

    Human breast milk contains three major HMO types:

    • fucosylated HMOs (35%–50%)
    • sialylated HMOs (12%–14%)
    • nonfucosylated neutral HMOs (42%–55%)

    One of the most common and prominent human milk oligosaccharides is called 2'-Fucosyllactose or 2'-FL for short. This HMO is just one of between 100 to 200 HMOs in all. Here is a list of some of the known HMOs:

    • 2′-FL
    • LNnT
    • 3'-FL
    • LNT
    • LNFP-I
    • 6'SL
    • LNFP-III
    • DSLNT
    • LDFT
    • LSTc
    • 3'SL
    • LNFP-II
    • LST-a
    • LST
    • LNDFH-II
    • LNFP-V

    Simply stated: 2'-FL is the most abundant HMO in human milk. Therefore it is often found in baby formula and more recently, in human milk oligosaccharide supplements designed for adults, like the flagship line offered by Layer Origin Nutrition

    How much 2'-Fucosyllactose (2'-FL) is in PureHMO™ Prebiotic supplements from Layer Origin Nutrition?

    Every product in Layer Origin Nutrition's line of gut health supplements for adults contains 2'-Fucosyllactose but the amount varies in each product as follows: 

    • PureHMO™ Prebiotic capsules (1300mg 2'-FL per serving) 
    • PureHMO™ Prebiotic powder (1950mg 2'-Fl per serving) 
    • PureHMO™ Prebiotic + Probiotic capsules (1000mg per serving) 

    What is akkermansia and how can you increase it?

    Akkermansia (akkermansia muciniphila) is a beneficial microbe that can affect your glucose metabolism, lipid metabolism, and intestinal immunity, according to multiple reports.10

    Blue Akkermansia Muciniphila bacteria graphic

    Research has indicated that particular food ingredients, such as polyphenols, may increase the abundance of Akkermansia muciniphila in the gut. Its name comes from the name of microbial ecologist Antoon Akkermans and the characteristic of “preferring mucin”. Thus, we arrive at Akkermansia muciniphila (Akkermansia). It accounts for one to four percent of intestinal bacteria in adults and is a species of bacteria that inhabits the large intestine. 

    Recent studies have indicated that Akkermansia is involved in obesity, glucose metabolism, and intestinal immunity. It mainly resides in the intestinal mucosa, an interface between the gut microbiome and host tissues.11

    Grapes, cranberries, red apple skins,  may all be able to increase the abundance of Akkermansia in your body. 
























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