Prof Jeremy Nicholson was the team leader from Imperial College on a study to investigate the possible roles of diet and gut bacteria.
An international team including scientists from the University of Pittsburgh and Imperial College London carried out a study with a group of 20 African American volunteers and another group of 20 participants from rural South Africa. The two groups swapped diets under tightly controlled conditions for two weeks.
Read more on this via the coverage below and the BBC World Service interview which features Prof Nicholson (32 minutes in).
Guardian: Bowel cancer risk may be reduced by rural African diet, study finds
Imperial: Diet swap has dramatic effects on colon cancer risk for Americans and Africans
BBC: Diet swap experiment reveals junk food’s harm to gut