Best Foods To Prevent Colon Cancer
In just two weeks, a high-fiber, low-fat diet dramatically reduced biomarkers of colon cancer risk, recently reported scientists from the University of Pittsburgh and Imperial College in London.
The scientists recruited 20 African Americans ages 50 to 65 years living in the Pittsburgh area and 20 black South Africans, also ages 50 to 65, living in the rural Kwazulu region.
Americans and Rural Africans Swap Diets
For 14 days, the rural South Africans quit their regular diet and ate American-style; the Americans put their cheeseburgers and other typically American foods aside and ate fiber-rich, Kwazulu food.
Conditions were tightly controlled. All foods were provided by the scientists and chefs involved in the study.
- Beef Sausage Links
- Hash Browns
- Beef Bacon
- Rice Krispies
- French Fries
- Meatballs and Spaghetti
- Beef Hot Dogs
- White Rice
- Mashed Potatoes and Gravy
- Macaroni and Cheese
- Beef BBQ Ribs
- Steak Fries
- Spinach with Red Peppers and Onions
- Corn Biscuits
- Salmon Croquettes
- Veggie-Corn Dogs
- Mango Slices
- Catfish Nuggets Breaded with Maize (Corn)
- Kale Salads with Maize Croutons
- Navy Bean Soup
- Okra and Tomatoes
- Black-Eyed Peas and Corn Muffins
- Pineapple Slices
- Lentils and Brown Rice
- African Potato Salad
- Fish (Tilapia) Tacos
Cancer Rates 13 Times Higher
The two groups were chosen in part because of their vastly differing rates of colon cancer. “The prevalence of colon cancer is about 13 times higher in African Americans than in black populations living in rural South Africa,” notes Kimberly Gomer, MS, RD, LDN, educator and Director of Nutrition at the Pritikin Longevity Center in Miami.
And sure enough, pre-study colonoscopies on the subjects revealed that nearly half of the Americans had polyps in their colons. From these precancerous polyps arise the majority of colon cancers. None of the South Africans had polyps.
In addition to pre- and post-study colonoscopies, the researchers measured several biological markers that indicate colon cancer risk, including levels of inflammation in the colon. They also studied samples of bacteria taken from the colon.
Secondary Bile Acids
One key biomarker investigated was secondary bile acids. Secondary bile acids are produced during digestion. After we eat a fatty meal, the liver releases bile into the intestines to aid in the digestion of fat particles. Think of bile acids as the detergent in our digestive systems, and just as we need more detergent when dealing with greasy, fat-encrusted pots and pans, we need more detergent, or bile, when dealing with our body’s intake of fatty meals. But ultimately that’s a problem because more bile means that more secondary bile acids are produced. Secondary bile acids have been shown to be carcinogenic.2
After just two weeks on the American diet, the Africans from rural South Africa had significantly more inflammation in the colon and dramatically increased biomarkers in the gut indicating cancer risk, including secondary bile acids, which had shot up 400%.
The other group, the Americans eating the rural, fiber-rich South African diet, had the exact opposite response. Within two weeks, their tests showed remarkable reductions in levels of inflammation and secondary bile acids, which fell 70%, as well as other changes in gut bacteria indicating that colon cancer risk had plummeted.
“Quickly and dramatically…”
Noted Dr. Jeremy Nicholson, lead author from the research team at Imperial College in London: “The findings suggest that people can substantially lower their risk of colon cancer by eating more fiber. This is not new in itself but what is really surprising is how quickly and dramatically the risk markers can switch in both groups following diet change.
“These findings also raise serious concerns that the progressive westernization of African communities may lead to the emergence of colon cancer as a major health issue.”
Best Foods To Prevent Colon Cancer
Not sure which foods are highest in fiber?
“Let’s keep it simple,” counsels Kimberly Gomer. The diet she teaches guests, the Pritikin Eating Plan, is fiber-rich. “If you focus your daily diet on plant foods that are in their natural state, foods that look as if they actually came out of the ground, chances are you’ll be eating plenty of fiber.”
High-Fiber Food Groups
- Beans and legumes
- Whole grains like oatmeal, barley, and whole-wheat pasta
- Starchy vegetables like peas, potatoes, yams, and corn
The list below gives you a sense of foods that are fiber stars. The average American consumes approximately 10 to 15 grams of dietary fiber per day. A healthier intake, one for prevention of colon cancer and many other diseases, is likely at least three times that amount.
|Serving Size||Total Fiber (Grams)|
|Navy beans, cooked||1 cup||19|
|Split peas, cooked||1 cup||16|
|Lentils, cooked||1 cup||16|
|Black beans, cooked||1 cup||15|
|Pinto beans, cooked||1 cup||15|
|Lima beans, cooked||1 cup||13|
|Garbanzo beans, cooked||1 cup||13|
|Artichoke, cooked||1 medium||10|
|Acorn squash, cooked||1 cup||9|
|Green peas, cooked||1 cup||9|
|Guava, raw||1 cup||9|
|Bulgar, cooked||1 cup||8|
|Russet potato with skin||1 large||7|
|Boysenberries, frozen||1 cup||7|
|Pear, with skin||1 medium||6|
|Pasta, whole-wheat, cooked||1 cup||6|
|Barley, pearled, cooked||1 cup||6|
|Brussels sprouts, cooked||1 cup||6|
|Jicama, raw||1 cup||6|
|Edamame, frozen||1 cup||6|
|Broccoli, cooked||1 cup||5|
|Turnip greens, cooked||1 cup||5|
|Quinoa, cooked||1 cup||5|
|Mustard greens, cooked||1 cup||5|
|Collard greens, cooked||1 cup||5|
|Cauliflower, cooked||1 cup||5|
|Yam, cooked||1 cup||5|
|Apple, with skin||1 medium||4|
Best Foods For Weight Loss
Another bonus of foods naturally rich in fiber is that they can greatly enhance our weight-loss efforts. That’s because foods full of fiber have a high satiety-to-calorie ratio, meaning, they can help us feel full – and for a longer period of time – but on a lot fewer calories than many other foods.
To illustrate: With one bowl of fiber-rich black bean soup (which tallies up about 300 calories), most of us are feeling pretty satisfied, ready to get up from the table. But the 300-plus calories in one slim energy bar can leave many of us asking, “Is that all there is?”
Critics of fiber-rich foods as best foods to prevent colon cancer often argue that epidemiological, or population-based, studies that have analyzed dietary fiber have provided inconsistent results. Some data indicate a link between high fiber consumption and reduced risk of colon cancer; some do not.
But the inconsistencies “may be due to the lack of a significant range of fiber intake among U.S. individuals,” points out Dr. James Barnard, professor emeritus of UCLA, in his recently published book Understanding Common Diseases and the Value of the Pritikin Eating and Exercise Program.
In other words, even among those in the U.S. consuming a higher level (by American standards) of fiber (about 30 to 35 grams of fiber daily), that level still may not be high enough to result in beneficial biological changes that thwart cancer growth. Indeed, in clinical trials, fiber supplementation of about 35 grams daily has generally failed to reduce polyp recurrence.3
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Optimal Fiber Intake
Dr. Denis Burkitt, who in the 1960s and 70s studied the diets, stools, and health of African villagers, concluded from his research that total fiber intake should exceed 50 grams daily for disease prevention.4
In the two-week diet swap study, the Americans eating the plant-rich diet of the rural South Africans increased their average daily fiber intake from 14 to 55 grams, and they reduced their overall fat intake from 35% to 16% of total calories consumed – a diet that in many ways mirrors the Pritikin Eating Plan taught at the Pritikin Longevity Center.
The Africans eating the American-style diet, by contrast, reduced their fiber intake from 66 grams a day to 12 grams, and their fat intake increased from 16% to 52% of total calories consumed.
Colon Cancer Rates | International Studies
The data affirming the benefits of a diet high in foods naturally rich in fiber (not fiber supplements) are compelling. To begin with, rates of colon cancer, which is the fourth most common cause of death from cancer worldwide, are much higher in western, industrialized countries than in countries in Africa and the Far East, where many populations still tend to eat traditional, fiber-rich diets.5
Low Intake of Fruits and Vegetables, High Rates of Colon Cancer
And consistently, population studies have found that diets low in fruit and vegetables are associated with higher risk of colon cancer.6
High-Fat Diet, High Colon Cancer Rates
There is also a large international variation in mortality from colon cancer that correlates with dietary fat.7 Put simply, those countries eating a high-fat diet tend to have high rates of colon cancer, and those eating diets naturally low in fat have low colon cancer rates.
Just One Generation
Moreover, long-term studies of people from Japan who migrated to Hawaii (and left behind their traditional plant-based, fiber-rich diets) have shown that it took just one generation of eating a Western-style, low-fiber, high-meat diet to change their low incidence of colon cancer to the high rates of Western-eating Hawaiians.8
And the large European Prospective Investigation in Cancer and Nutrition reported high rates of colon cancer with decreased consumption of fiber and increased consumption of meat.9
Research on Pritikin Program
Interestingly, a study10 published more than 25 years ago on women attending the Pritikin Longevity Center echoes the findings of the recently published study on African Americans and rural Africans. At the beginning and end of their three-week healthy lifestyle program at Pritikin, stool samples from the women were collected by scientists at UCLA. Within those three weeks, lead author Dr. James Barnard and colleagues reported, stool weight was increased by 69% and total secondary bile acids fell by 60%.
“These results,” reported the UCLA researchers, “suggest that switching from a high-fat, low-fiber diet to a low-fat, high-fiber diet can reduce the excretion of bile acids which are thought to be involved in the promotion of colon cancer.”
In addition to diet, another lifestyle factor that might aid in reducing the risk of colon cancer is regular exercise. Following more than 47,000 American male health professionals, researchers led by Edward Giovannucci, MD, of Harvard University Medical School found that being physically active about 45 minutes daily reduced the risk for colon cancer by 50%.
Preventing Colon Cancer Recurrence
It may never be too late to start.
Among people who’ve had colon cancer, a large-scale investigation12 recently discovered that healthy Pritikin-style habits may reduce the risk of the cancer returning.
The research team involved 14 institutions, including Memorial Sloan Kettering Cancer Center in New York and University of California, San Francisco. The scientists followed nearly 1,000 people with stage III colon cancer over the course of seven years.
The results: The colon cancer patients who ate a diet high in fruits, vegetables, and whole grains and low in red and processed meats, exercised regularly, and maintained a healthy body weight were rewarded with a significantly lower risk of cancer recurrence or death compared to the patients who did not adopt these healthy habits.
Colon cancer survivors following the healthy lifestyle had a 42% reduced risk of death and 31% reduced risk of cancer recurrence, reported the scientists at the 2017 annual gathering of the American Society of Clinical Oncology in Chicago.
Best Foods To Prevent Colon Cancer | Summing Up
“The results of the new diet swap study, plus the study on the benefits of the Pritikin Program, are motivating. They show that if Americans switch from their typical modern diet to a diet that is far lower in fatty animal products and composed largely of whole grains, beans, fruits, and vegetables, like the Pritikin Eating Plan, they’ll get immediate benefits. They’ll quickly and dramatically alter the microbiota [microorganisms] of their colons and reduce the inflammation and other chemical changes that promote colon cancer,” states Kimberly Gomer.
The results of this research are also incredibly hopeful, notes Dr. Stephen O’Keefe at the University of Pittsburgh, lead author of the diet swap study.
“They show that it is likely never too late to change your diet to change your risk of colon cancer.”
- 1 Nature Communications, 2015; 6: 6342.
- 2 Archives of Toxicology, 2011; 85(8): 863.
- 3 Asano TKMR. Dietary fibre for the prevention of colorectal adenomas and carcinomas (Review). The Cochrane Library. 2008; (4).
- 4 Pathologia et Microbiologia, 1973; 39 (3):177.
- 5 International Journal of Cancer, 2010; 127 (12): 2893.
- 6 Cancer Causes Control, 1991; 2: 427.
- 7 International Journal of Cancer, 1975; 15: 617.
- 8 Revue D’epidemiologie et de Sante Publique, 1992; 40: 425.
- 9 Lancet, 2003; 361: 1496.
- 10 Preventive Medicine, 1988; 17: 432.
- 11 Annals of Internal Medicine, 1995; 122: 327.
- 12 American Society of Clinical Oncology, 2017