Eating a diet similar to traditional South African cuisine may dramatically cut your risk of developing colon cancer, according to a new study published this week in the journal, Nature Communications.Colon cancer is the fourth most common cause of death from cancer worldwide. Black women are more likely to die from colon cancer than any other group of men or women in the United States, according to the Centers for Disease Control and Prevention in Atlanta.

To gain a better understanding of the role diet and stomach bacteria play in colon cancer risk, scientists from the University of Pittsburgh and Imperial College London carried out a small study with 20 African American volunteers and 20 volunteers from rural South Africa. The two groups switched diets and were monitored under tightly controlled conditions for two weeks. The study participants were given colonoscopies before and after the two-week trial.

The results were startling. The scientists found a remarkable difference in the colon cancer risk factors in the groups after just two weeks.

How Diet Changes the Colon

When the study began, almost half of the African American subjects already had polyps—abnormal growths in the bowel lining that can become cancer. The Americans also had high levels of inflammation in the bowel. None of the Africans had polyps.

After two weeks of eating the western diet, the African study participants showed a dramatic increase in markers of inflammation in the bowel and other biomarkers of colon cancer risk. The African Americans had the opposite result. After eating a traditional rural South African diet for two weeks, they had much lower levels of inflammation and other colon cancer risk factors.

The study found that a major reason for the changes in colon cancer risk was the way in which the bacteria in the gut [stomach and intestines] — the microbiome — changed to adapt to the new diet. In the American group, the researchers found that the African diet led to an increase in the production of butyrate, a byproduct of fiber metabolism that has important anti-cancer effects.

In the African group, levels of butyrate were reduced, increasing their colon cancer risk factors. The African participants were fed a typical low fiber, high fat American diet that included foods like hamburgers and fries.

Eating Like Our Ancestors

The research results confirmed the finding of previous studies showing that high-fiber, low-fat diets can greatly reduce a person’s chance of developing colon cancer, but the scientists were surprised by how quickly the change to a lower-fat, higher fiber diet produced positive results.

“We can’t definitively tell from these measurements that the change in their diet would have led to more cancer in the African group or less in the American group, but there is good evidence from other studies that the changes we observed are signs of cancer risk,”said Jeremy Nicholson, a professor in the department of Surgery and Cancer at Imperial College London and the team leader.

His colleague, James Kinross, a colorectal surgeon and a member of the research team added, “The gut microbiome is being increasingly recognized as an important contributor to human health. This research shows that gut bacteria are critically important for mediating the link between diet and colon cancer risk.”

The key difference between the rural African diet and African American diet is fiber from whole, not processed, foods. South African cuisine often consists of grilled or stewed meals (not fried), maize (corn) porridge that is something like grits, but not as processed as what you will find on American grocery shelves. Beetroot, pumpkin (like squash), cabbage, and carrots, and other fresh vegetables are staples.

To make your diet healthier, plan you meals around high-fiber foods like roots, tubers (potatoes, for example, but not fried), lightly cooked vegetables and beans (prepared without any type of meat), and minimally processed grains such as brown rice and quinoa.

And remember, you can experience the benefits of the high-fiber regimen in just two week, so it’s well worth the effort to get started.