Canadian researchers say they may have identified substances from the human gut that could alter Type A and B blood in Type O blood – a discovery that could make blood donation easier, especially in times of emergency.

People with type O negative blood are considered universal donors, because they can give blood to someone. Therefore, Type O-negative blood is always in high emergency during emergencies, when there is often little time to test a patient's blood group to make sure it matches a donor.

Those with the other types of blood – Type A and Type B – have antigens on their red blood cells that prevent their blood from being donated to those who do not match.

There has long been interest in finding a safe and effective way to remove the A or B antigens from red blood cells, says University With British Columbia, researcher biochemistry Stephen Withers.

"If you can remove those antigens, which are simply simple sugars, then you can convert A or B into O-blood," he explained in a statement.

He and his colleagues decided to look for enzymes that might be able to do the job using something called "metagenomics" to analyze the genes of multiple species of organisms.

They considered analyzing mosquitoes and leeches, which naturally degrade blood, but ultimately found good candidates in the enzymes of bacteria that live in the gut of humans and that help digestion.

They found a whole family of enzymes that use bacteria to extract sugars from mucin, the proteins that run along the intestinal wall.

They tested how well these enzymes removed the sugary antigens on Type A and Type B blood and found that they were 30 times more effective than previous candidates.

The team will present the results of their research so far Tuesday morning at the annual meeting of the American Chemical Society in Boston.

Withers now works together with colleagues from the Center for Blood Research of UBC to test the enzymes on a larger scale, with the aim to then proceed to clinical testing.

He also wants to develop the most efficient sugar-removing enzyme with the help of something called "directed evolution", a protein technique that simulates natural evolution.

"I am optimistic that we have a very interesting candidate to adjust donated blood to a normal type," Withers said.

"Of course it will have to go through many clinical trials to ensure that it does not have any adverse effects, but it looks promising."