Posted on Fri, 8 May 15
In a diet-swap study a traditional African diet reversed several markers of bowel cancer risk within just 2-weeks, while a modern American diet increased risk.
Traditional, minimally processed, plant-based diets are associated with lower risk for colon cancer, a leading cause of cancer related death in the industrialized world. And conversely, highly refined, highly processed, meat-based diets are associated with increased risk.
To see if a traditional diet could quickly change markers associated with bowel cancer risk a 2-week “diet-swap” study was conducted.
During the study 20 Africans were asked to eat a typical American-style diet (low fiber and high meat and fat) and 20 African American volunteers were asked to eat an African-style diet (high fiber and low meat and fat).
The diet switch increased biomarkers of inflammation and cancer risk in Africans and reduced them in the Americans.
Many of the benefits were due to changes in the gut microbiotia metabolic activity known to affect cancer risk, with increased fermentation of plant-foods and higher production of butyrate, which protects against cancer development.
There was also reduced microbial generation of pro-carcinogenic bile acids in Americans, and the reverse in Africans. Bile acids can promote cancer development, and higher levels are associated with increased colon cancer risk.
And colonoscopy revealed that there was also a reduction in signs of inflammation in the colon, and the cells in the colon wall stopped dividing as quickly. Such changes may also be related to cancer risk.
“Our study suggests that westernization of the diet induces changes in biomarkers of colon cancer risk in the colonic mucosa within two weeks” said lead investigator, Professor Stephen O'Keefe. “Perhaps even more importantly, a change in diet from a westernized composition to a 'traditional African' high fiber low fat diet reduced these biomarkers of cancer risk within two weeks, indicating that it is likely never too late to change your diet to change your risk of colon cancer."
- O'Keefe SJ, et al. Fat, fibre and cancer risk in African Americans and rural Africans. Nat Commun. 2015 Apr 28;6:6342.
- News Release. Diet swap has dramatic effects on colon cancer risk for Americans and Africans. 27 April 2015. Imperial College London.