Hundreds of living species. One extraordinary ecosystem.
BoobyBiome began as a research project, with three scientists asking a question hardly anyone had stopped to ask. The answer changed how we think about every drop.
Unlocking breakthroughs in breast milk research.
Breast milk is incredible, complex and not fully understood. We set out to change that.
Strain origins.
We began with breast milk and babies’ stool donations, isolating their bacteria to build our own culture collection. Every strain in Besyma has a breast milk or baby origin.
Bioinformatics.
We use high-resolution sequencing on our samples, then decode millions of data points to map the species present and how they might interact.
Artificial gut studies.
We model a baby’s gut using live gut cells, showing how our strains reduce inflammatory signals and help develop a healthy gut barrier.
Metabolomics.
We build genome-scale metabolic models to predict which metabolites our bacterial consortia produce, then confirm them with chromatography and mass spectrometry. These include short-chain fatty acids, key signalling molecules in a baby’s gut.
Synbiotic formulation.
We studied which complex breast milk sugars our bacteria digest, and what metabolites result. Besyma’s unique blend of these sugars is designed to give our strains a competitive advantage in a baby’s gut.
Oxygen changes breast milk.
When your baby latches, their mouth forms a natural seal against your skin, and milk passes from you to them without ever meeting the air. When pumping, oxygen is introduced and dissolves into the milk and settles in the space above it. Our research found that from that moment it begins to degrade the living parts and vitamin content of the milk.
Those living parts are unique to you. The bacteria and vitamins in your milk are shaped by your body and tuned to what your baby needs.
Byomi keeps your milk as close to the moment it was expressed as possible. A small pod draws the oxygen out of the milk and the air above it. In our study, milk stored this way held on to its living bacteria and its vitamin C for far longer, so more of your microbiome reaches your baby’s gut, in turn building their gut microbiome and helping to lay the foundations of their immunity.
Mothers conducted a blind smell test on stored milk, comparing milk kept with and without BYOMI to determine which smelled fresher.
chose the milk stored with BYOMI
Difference in how often each word was used, percentage points
Vertical axis: living bifidobacteria, % still viable · horizontal: days in the fridge
*Average of B. longum, B. bifidum and B. breve. From our 2026 study, currently under peer review.
Breast milk, under the microscope.
Breast milk is more than nutrition: it’s a dynamic ecosystem of microbes, sugars, antioxidants, lipids and immune-active molecules that have evolved with us over millions of years.
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Genus: Bifidobacterium · facultative anaerobe · thrives without oxygenThe keystone species
The gut microbiome of breastfed infants looks distinctly different from that of formula-fed infants, and Bifidobacterium dominance is the defining feature. These bacteria are particularly well adapted to degrade the complex sugars found in breast milk, producing secondary metabolites (including acetate and lactate) that have independent functions. Additionally, Bifidobacteria lower gut pH, synthesise B vitamins including folate, biotin and riboflavin, crowd out opportunistic bacteria, strengthen the gut barrier and signal directly to the developing immune system. Strikingly, Bifidobacteria abundance in breastfed infants has fallen meaningfully over the past century, one of the more notable shifts documented in modern gut microbiome research. Bifidobacteria don’t just indicate a healthy early microbiome, they’re actively building it.
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Genus: Lactobacillus · aerotolerant · lactic acid producerThe housekeeper
Lactobacilli are among the first bacteria to shape the infant gut, as they occupy both the breast milk and vaginal microbiome niches. Lactobacilli are so efficient at fermenting sugars into lactic acid that they derive their name from this activity. Generation of lactic acid reduces the local pH of the gut, favouring acid-tolerant beneficial microbes while making the environment inhospitable to opportunistic pathogens. They also work synergistically with Bifidobacteria, cross-feeding metabolic by-products to reinforce the same acidic, low-oxygen niche. This reflects a priority effect: microbes that colonise first exert a disproportionate influence on which species subsequently establish, meaning early colonisers such as Lactobacilli have a lasting effect on the gut’s eventual microbial composition.
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Human milk oligosaccharide · complex carbohydrate · genetically determinedThe multi-talented sugars
Human milk oligosaccharides (HMOs) are among the most abundant complex carbohydrates in breast milk. Every mother’s HMO profile is different: a genetic trait called secretor status determines whether she produces certain HMO structures, meaning each baby receives a genuinely unique combination of sugars. Babies cannot digest HMOs themselves; instead, these sugars act as selective food for Bifidobacteria, fuelling the production of beneficial metabolites and giving the bacteria a competitive edge over less desirable species. HMOs perform three crucial duties: feeding beneficial bacteria, acting as decoys that intercept pathogens like certain E. coli strains and rotavirus before they can attach to the gut wall, and signalling directly to the immune system.
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Vitamins C & E · antioxidant compounds · limit oxidative damageThe redox regulators
Newborns have immature intrinsic antioxidant defence systems that develop gradually. Breast milk compensates for this by providing antioxidant compounds, such as vitamins C and E, which neutralise reactive oxygen species. These are unstable molecules that can damage cell membranes, proteins and DNA when present in excess. Vitamins C and E function as a redox pair. They increase the overall efficiency of the antioxidant defence system as vitamin C reduces oxidised vitamin E back to its active form. This protective effect extends beyond the gut, contributing to redox balance throughout the body. Separately, vitamin C also acts as an essential cofactor for collagen synthesis, supporting the development of connective tissue, skin and blood vessels.
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Omega-3 fatty acid · long-chain polyunsaturated · structural & signallingThe membrane architect
Breast milk supplies essential fatty acids, including the long-chain polyunsaturated omega-3 DHA. DHA makes up approximately half of the brain’s total lipid content and the majority of the fatty acids in its cell membranes, making it a core structural membrane component essential for neurological and visual development. While omega-3 fatty acids are a necessary energy source, they also perform fundamental signalling throughout the body. Due to its chemical structure, DHA confers membrane fluidity and function but is also vulnerable to degradation by reactive oxygen species. DHA therefore depends on the antioxidants available in breast milk for its protection.
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Immune molecules · antibodies, cytokines & peptides · protect & regulateThe immune network
Breast milk provides an extraordinary range of immune molecules, including secretory IgA antibodies, lactoferrin, cytokines, antimicrobial peptides and immune cells. Many of these antibodies are pathogen-specific: immune cells from the mother’s own gut migrate to the mammary gland during lactation and produce antibodies targeted at recently encountered pathogens, aligning her milk’s defences with their shared environment. Lactoferrin works by sequestering iron, a nutrient essential for bacterial DNA synthesis: this starves iron-dependent pathogens while sparing beneficial bacteria such as Bifidobacteria and Lactobacillus, which have naturally low iron requirements. Some act immediately, binding and neutralising harmful microbes; others regulate inflammation or support the maturation of your baby’s own immune system.
A baby’s health begins in the gut.
The gut microbiome is built from day one, seeded by the living bacteria breast milk delivers. Research links those first colonisers to how a baby’s immune system and metabolism learn to regulate themselves.
Borrego-Ruiz & Borrego, Microbiome Research Reports, 2025. Read the paper →
