Cancer. A few decades ago it was a disease so frightening and misunderstood that people would often whisper when talking about it.

Today we’re inundated by messages about cancer, its causes and how to reduce our own risk. Certain behaviors, like smoking cigarettes, are now well known to increase cancer risk. We know that a healthy diet and regular exercise can help guard against cancer, too.

Still, there aren't many recommendations a doctor can make that come with a near-guarantee they'll help you avoid certain cancers. That’s why it’s striking to hear someone like Dr. Stephen O’Keefe address a specific disease with such a direct, simple message: Add fiber to your diet and you can pretty much kiss your risk of colon cancer goodbye.

Now O’Keefe is seeking volunteers to participate in research that has the potential to eliminate a leading cause of illness and mortality among Alaska Native people.

Understanding colon cancer in Alaska Native people

O’Keefe leads the Cancer Biome Group at the University of Pittsburgh Center for Medicine and the Microbiome and is the director of the African Microbiome Institute at Stellenbosch University in Cape Town, South Africa. A year and a half ago, he embarked on a new study in partnership with Alaska Native Tribal Health Consortium to learn more about the epidemic of colon cancer among Alaska Native people.

“Colon cancer is devastating in the (Alaska Native) community,” O’Keefe said. “It’s the highest death rate of colon cancer in the world.”

And, he added: “It’s totally preventable.”

The Alaska study anticipates results similar to those seen in O’Keefe’s prior research in South Africa: If you add more fiber to the diets of Alaska Native people, those good gut bacteria will flourish to combat carcinogens like fat and smoke.

O’Keefe said he believes the traditional Alaska Native subsistence diet is “superior” in many ways, especially because of its high concentration of Omega-3 fatty acids. But like most Americans, Alaska Native people consume less fiber than is ideal -- about 15g per day. That’s about as much fiber as is contained in one cup of cooked beans or three cups of raw blueberries.

The USDA currently recommends 34g/day for men and 28g/day for women -- and in fact, most Americans don’t even get that much fiber in their daily diet. Based on his research, O’Keefe said he thinks even those recommendations don’t go far enough.

“We feel that the fiber recommendations in the USA put forward by USDA … are insufficient to meet colonic needs,” O’Keefe said.

O’Keefe said he believes 50g per day is a better target. That’s the amount being administered to participants in the ANTHC study. It’s a number based on a real-world example: the traditional diet of rural South Africa, where colon cancer is very uncommon, and where O’Keefe’s work in Alaska has its roots.

From Africa to Alaska

In 2015, O’Keefe was the lead author of a study that examined the wild disparity in colon health between rural South African and African American people. While colon cancer is rare among rural South Africans, African Americans experience high rates of colorectal cancer.

"When we did colonoscopies in Africa, you very, very rarely saw polyps or diverticularity or other problems in the colon," O'Keefe said. "When we went to look at similar problems in Virginia and then Pennsylvania, if you did colonoscopies on African Americans, you were very likely to find polyps. It was a striking difference."

The difference, O'Keefe found, came down to diet. The traditional African diet includes lots of high-fiber vegetables and some lean meat; on average, African study participants consumed in excess of 50g of fiber per day. African American participants tended to eat a diet high in meat and fats and low in fiber -- an average of 14g per day.

At that point, O'Keefe's research team began looking at what effect those different diets have on "gut bacteria" -- the microbes that live in the colon.

"We began to understand the microbiota and how it might mediate risk," O'Keefe said.

The makeup of the bacteria in your colon depends on the diet you consume. When you eat a high-fiber diet, you're encouraging the growth of bacteria that degrade starches and ferment fiber to produce nutrients called short-chain fatty acids.

"The good thing about fiber fermentation products is they produce this one chemical called butyrate, which can actually antagonize these cells that are carcinogens," O'Keefe said. They can help protect the body against other kinds of cancers, too. "If you do have high intakes of fiber and produce a lot of short chain fatty acids, they're not only used by the colon itself. They're absorbed by the body and can act as inhibitors of inflammation throughout the body."

What was incredible about the South Africa study was that it indicated that dietary changes can have immediate effects -- both positive and negative.

"We switched the diets of African Americans and rural Africans, and within two weeks we showed dramatic changes in the microbiota in both groups," O’Keefe said.

Good bacteria flourished in the colons of African American participants who had switched to a high-fiber, low-fat diet, while those cancer-fighting gut microbes had quickly diminished among the rural South African subjects who’d replaced fiber with protein and fat.

“Diet, indeed, was the main driver,” O’Keefe said.

Benefits beyond colon health

Avoiding colon cancer isn’t the only reason to consider adding fiber to your diet. Short-chain fatty acids have multiple benefits. Acetate, for example, has been shown to increase insulin sensitivity, making it useful for patients with Type 2 diabetes, according to O’Keefe.

But that’s not all.

“It’s even more powerful than that,” O’Keefe said. “If you take a fiber-rich diet … (you reduce risk of) about nine other common cancers in westernized society, such as breast cancer, liver cancer, and lung cancer.” Cancer mortality in general is lower among people who follow a plant-based diet, he added.

If necessary, a fiber supplement will get the job done -- that’s what they’re using in the study -- but O’Keefe said whole foods are the best source of fiber. Affordable high-fiber foods are available canned and frozen, but they can also be found growing wild across Alaska.

According to the Alaska Native Traditional Food Guide, Alaskans living in rural areas harvest about 44 million pounds of wild food each year, an average of about 375 pounds per person. Wild foods aren’t just more affordable and easier to access than foods shipped in from urban areas; gathering them comes with the added benefit of physical activity. And wild plants can be excellent sources of fiber. One cup of raw blueberries, for example, has 4 grams of fiber, and one cup of crowberries or wild blackberries has 5 grams. Wild greens such as fiddlehead, fireweed, nettle, seaweed and sourdock are also high in fiber.

Whatever the source, O’Keefe said there’s no question that a high-fiber, plant-rich diet is the key to stopping colorectal cancer -- and he hopes the study, and its findings, will be the beginning of the end of colon cancer’s devastating effect on Alaska Native families.

“It’s almost totally preventable by dietary means,” he said.

ANTHC is still enrolling participants in the fiber study. To learn more or take part, contact a study staff member at 907-229-0712.

This story was sponsored by Alaska Native Tribal Health Consortium, a statewide nonprofit Tribal health organization designed to meet the unique health needs of more than 175,000 Alaska Native and American Indian people living in Alaska.

This story was sponsored by Alaska Native Tribal Health Consortium, a statewide nonprofit Tribal health organization designed to meet the unique health needs of more than 175,000 Alaska Native and American Indian people living in Alaska.

This story was produced by the creative services department of the Anchorage Daily News in collaboration with Alaska Native Tribal Health Consortium. The ADN newsroom was not involved in its production.