Colon cancer is responsible for 600,000 deaths per year worldwide and is the fourth most common cause of death from cancer. Interestingly, the rates of colon cancer are much higher in western countries versus the areas in the Far East or Africa. Moreover, the African American community are seen to have a higher prevalence of the disease than people of African descent in other areas of the world.
Western diets are high in protein and fat while low in fiber. This kind of diet is likely to raise risk of colon cancer. On the other hand, a traditional African diet is mostly the opposite, being high in fiber, and low in fat and protein. This led researchers from the University of Pittsburgh and Imperial College London to design a study where African American and rural South African volunteers swapped diets. By just swapping their diets for as little as two weeks there were significant consequences.
Each volunteer had colonoscopy exams before and after swapping their diets. Other biological markers that indicate risk of colon cancer as well as bacteria samples from the colon were also measured. Two weeks after the diet swap, the American group eating an African diet had significantly less colon inflammation and reduced cancer risk biomarkers. The African group consuming the western diet, however, experienced a drastic increase in measurements indicating cancer risk.
What is the cause of the major effects? One major reason for these changes in cancer risk that was found in the study is the alteration of the gut microbiome, or gut bacteria. The microbiome altered their metabolism in response to the new diet. Researchers found the American group consuming an African diet had an increased production of butyrate which has anti-cancer effects. A member of the Imperial research group, Dr. James Kinross, states that the gut microbiome has been recognized to serve important contributions to human health.
The research in this particular study showed the critical importance that the gut bacteria had on mediating the association between diet and colon cancer risk. Due to the findings, it’s expected more research will be done to develop therapies which directly target gut bacteria as a method of preventing and treating cancer.