Conventional wisdom says that unhealthy Western diets are a contributor to numerous chronic diseases, including cancer. A recent study adds evidence to that notion, finding that a traditional high-fiber South African diet can reduce indicators of colon cancer compared to protein and fat-heavy American diets.
The study, published in Nature Communications, looked at the rates of cancer risk factors in rural Africans living in KwaZulu-Natal and in African Americans living in Pittsburgh. Researchers analyzed the respective diets of their sample populations, then switched them for two weeks to see if it would make a difference.
The results were striking. Initially, the American subjects showed far greater risk for colon cancer, but after 14 days of swapping diets the Africans’ risk factors shot up while the Americans’ dropped dramatically. The species of gut bacteria present also changed with the diet — subjects eating the African food harbored bacteria that are disfavorable to the onset of cancer, and vice versa.
“The higher [colon cancer] rates are associated with higher animal protein and fat, and lower fibre consumption, higher colonic secondary bile acids, lower colonic short-chain fatty acid quantities and higher mucosal proliferative biomarkers of cancer risk in otherwise healthy middle-aged volunteers,” the study states.
“We were astounded at the degree of change. We thought we’d find a few changes here and there when they swapped diets, but this mirror image was totally unexpected,” researcher Stephen O’Keefe said in the study.
According to the study, colon cancer rates in African Americans are 65 in 100,000, while in rural South Africans they are only 5 in 100,000. Diet has long been a suspect in the discrepancy, particularly when it comes to the amount of fiber consumed.
Sure enough, the African diet comprised of primarily corn fritters, mango slices, bean soup and fish tacos, very low in fat and high in fiber. The American diet, on the other hand, was high in fat and protein, including sausages, hash browns, burgers and fries.
The takeaway? The composition of your diet is likely to play a large role when it comes to susceptibility to colon cancer. Sometime to think about next time you head to the grocery store or out for a meal at a restaurant.
“What is startling to me is how profoundly the microbes, metabolism and cancer risk factors change in just two weeks of diet change. It means to me that diet and environment and microbial genes are likely to be much more important than individual human genes in determining individual colonic cancer risks,” study co-author Jeremy Nicholson said to The Guardian. “Certainly it shows that your possible fate is not just determined by the genetic dice at birth. How you roll the dice in the game is probably more important.”
There was one caveat about switching to the African diet: It increased the amount of flatulence in its temporary adopters. Small price to pay for, perhaps, for reducing cancer risk.