More than half your body is not human
“They are essential to your health,” says Prof Ruth Ley, the director of the department
of microbiome science at the Max Planck Institute, “your body isn’t just you”.
“Where work on the microbiome comes in is seeing how changes in the microbiome,
that happened as a result of the success we’ve had fighting pathogens, have now contributed to a whole new set of diseases that we have to deal with.”
I met Dr Trevor Lawley at the Wellcome Trust Sanger Institute, where he is trying
to grow the whole microbiome from healthy patients and those who are ill.
“In a diseased state there could be bugs missing, for example, the concept is to reintroduce those.”
He says: “We were able to show that if you take lean
and obese humans and take their faeces and transplant the bacteria into mice you can make the mouse thinner or fatter depending on whose microbiome it got.”
Prof Rob Knight, from University of California San Diego, told the BBC: “You’re more microbe than you are human.”
Dr Lawley says there’s growing evidence that repairing someone’s microbiome “can actually lead
to remission” in diseases such as ulcerative colitis, a type of inflammatory bowel disease.
“That’s been refined much closer to one-to-one, so the current estimate is you’re about 43% human if you’re counting up all the cells,” he says.
And he added: “I think for a lot of diseases we study it’s going to be defined mixtures of bugs, maybe 10 or 15 that are going into a patient.”