A University of British Columbia team led by Stephen Withers were able to convert Type A blood to Type O using enzymes from a gut bacterium called Flavonifractor plautii.

I’m Type A … I wonder if I have any of that microbe in my gut?

The answer is yes:

(Those numbers are parts per million).

This microbe seems pretty common in most of the samples people have sent me, with perhaps a bit more variation among people with some type of gut problem compared to those who are healthy.

I realize how much I expose myself as an amateur for even asking this question, since it’s hard to imagine any biological basis for how a gut microbe could relate to person’s blood type, but wouldn’t it be cool to go back to these people and see if there’s a relationship between blood type and presence/absence/abundance of this microbe?