A discovery hidden in human intestines might soon solve one of healthcare's most persistent challenges.
Imagine a world where blood banks never face shortages of the most critically needed blood type. This future may be closer than we think, thanks to an unexpected ally: bacteria living in our gut. Scientists have discovered that enzymes produced by gut microbes can convert donated A and B blood types into universal type O, potentially revolutionizing blood transfusion medicine and ensuring safer, more abundant blood supplies for everyone.
The constant scarcity of blood supplies is a global health crisis. The World Health Organization reports that blood donation services in many countries cannot meet demand, with an estimated 112 million annual donations needed to cover global needs 1 .
The problem is particularly acute for type O blood, which is considered the "universal donor" type because it lacks A and B antigens that can trigger fatal immune reactions if mismatched 5 .
This makes type O blood especially valuable in emergency situations when there's no time to test a patient's blood type. As a result, health systems maintain a large—and often unmet—need for donor group O blood 6 . The American Red Cross declared an emergency blood shortage in 2024, with its national blood inventory dropping more than 25%, leading to transfusion delays and rationing that endanger patients 7 .
Type O is the most common blood type globally, making universal conversion technology particularly valuable.
| Country Income Level | Share of Global Population | Share of Blood Donations |
|---|---|---|
| High-income countries | 16% | 40% |
| Low- and middle-income countries | 84% | 60% |
Source: World Health Organization data from 1
The breakthrough came from researchers at the Technical University of Denmark and Sweden's Lund University who turned their attention to an unlikely source: the human gut. Specifically, they studied Akkermansia muciniphila, a bacterium that naturally resides in the mucus lining of our intestines 5 .
Akkermansia muciniphila lives in intestinal mucus
Bacteria produce enzymes to break down mucus sugars
Enzymes can remove A and B antigens from blood cells
"What is special about the mucosa is that bacteria, which are able to live on this material, often have tailor-made enzymes to break down mucosal sugar structures, which include blood group ABO antigens," explained Professor Maher Abou Hachem, one of the lead researchers on the study 5 .
The researchers hypothesized that if these enzymes could break down mucus sugars similar to blood group antigens, they might also work on actual blood antigens. Their hypothesis proved correct—the bacterial enzymes efficiently stripped away the sugar molecules that determine A and B blood types, effectively converting them into type O 5 6 .
Researchers harvested 23 different glycosyl hydrolase enzymes produced by Akkermansia muciniphila bacteria 5 .
The team prepared red blood cells of types A and B for enzyme treatment.
They applied combinations of the bacterial enzymes to the blood samples, testing which mixtures most effectively removed A and B antigens.
The converted blood was then tested for compatibility with type O plasma to check if the conversion successfully eliminated immune-triggering antigens 5 .
The findings, published in Nature Microbiology, demonstrated that "enzyme cocktails" derived from the gut bacteria successfully removed not only the well-known A and B antigens but also extended variants that weren't previously recognized as problematic for transfusion safety 5 .
Most importantly, the enzymatic removal of these antigens "significantly improved compatibility with group O plasmas," meaning the converted blood was far less likely to trigger dangerous immune reactions in recipients 5 . The researchers noted they are closer to producing universal blood from group B donors, though more work remains for the more complex group A blood 5 .
| Material/Equipment | Function in the Experiment |
|---|---|
| Akkermansia muciniphila bacteria | Source of exoglycosidase enzymes that break down blood group antigens |
| Glycosyl hydrolase enzymes | Primary agents that remove A and B antigens from red blood cells |
| Red blood cells (types A & B) | Substrate for enzyme testing and conversion evaluation |
| Type O plasma | Testing solution to verify compatibility of converted blood |
| Structural analysis tools | Identified previously unknown carbohydrate-binding modules in effective enzymes |
While the gut enzyme approach shows remarkable promise, it's not the only scientific frontier in addressing blood shortages. Researchers worldwide are pursuing multiple strategies:
Scientists at Stanford and UCSF are using CRISPR gene-editing technology to alter bone marrow stem cells, enhancing their hemoglobin production in red blood cells 1 .
Researchers at Penn State are developing tiny artificial red blood cells that can transport just as much oxygen as natural cells despite being only one-tenth the size.
The U.S. Defense Department is backing research into a "Red Blood Cell Factory" to help soldiers cope with oxygen deprivation in extreme conditions 1 .
Other researchers are coaxing stem cells into becoming blood cells in bioreactors that mimic bone marrow environments, though this approach currently costs $8,000-$15,000 per unit of red blood cells compared to $250 for donor blood 7 .
| Technology | Key Advantage | Development Stage |
|---|---|---|
| Gut enzyme conversion | Creates universal donor blood from existing donations | Patent pending, aiming for clinical trials |
| CRISPR genetic modification | Increases oxygen-carrying capacity of red blood cells | Early trials show promise but modest returns |
| Nano artificial RBCs | Room temperature storage, ideal for emergencies | Laboratory development stage |
| Stem cell culturing | Eliminates donor dependency | Early human trials, cost-prohibitive |
The Danish and Swedish research teams have applied for a patent on their enzyme method and plan to continue their joint project over the next three years, with the goal of progressing to controlled patient trials and eventually commercial production 5 .
"We are close to being able to produce universal blood from group B donors, while there is still work to be done to convert the more complex group A blood," said Professor Hachem 5 . "Our focus is now to investigate in detail if there are additional obstacles and how we can improve our enzymes to reach the ultimate goal of universal blood production."
If successful, this technology could revolutionize blood bank management. "Universal blood will create a more efficient utilization of donor blood, and also avoid giving ABO-mismatched transfusions by mistake," noted Professor Martin Olsson of Lund University. "When we can create ABO-universal donor blood, we will simplify the logistics of transporting and administering safe blood products, while at the same time minimizing blood waste" 5 .
The discovery that gut bacteria enzymes can transform blood types represents a remarkable convergence of microbiology and transfusion medicine. While challenges remain in scaling the technology for widespread clinical use, this research offers hope for a future with more robust blood supplies and safer transfusions.
As climate change increasingly stresses blood reserves through extreme weather events that disrupt donations 3 , and with global blood demand continually rising, such innovations become increasingly vital. The solution to one of healthcare's most persistent challenges may indeed lie within us—quite literally in our gut bacteria—waiting to be harnessed.
As research continues, the dream of universal donor blood for all patients moves closer to reality, promising to save countless lives through the microscopic workings of our internal ecosystems.