Diet, fiber, cancer

March 27 2016

Diet, fiber, cancer

This small but fascinating study published April 2015 in Nature Communications looked at what happened when 20 Americans switched their diet with 20 South Africans for 2 weeks.

Here are my take home points.

The purpose of the study was investigate further the role of fiber and animal fat in increasing colon cancer by comparing two groups of people with very different diets and also very differing rates of colon cancer: African Americans and rural South Africans.

The rate of colon cancer among African Americans is 65 per 100,000 people while for rural South Africans, it is <5 per 100,000.

Many factors are likely at play for the above numbers; the investigators of this study were interested in looking at the role DIET specifically played. To do this, the investigators decided to see what would happen if a group of volunteers from South Africa would swap diets for two week with a group of African American volunteers from Pittsburg.

To perform the diet swap, the study investigators first interviewed the volunteers on what the they ate on a daily basis and as suspected, it was found that the Americans were eating 2-3 times as much animal protein than the South Africans. Recorded diet sample from the American group: sausage links (breakfast), hamburger and fries (lunch), meatloaf and rice (dinner). Recorded diet sample from the South African group: maize (corn) fritters (breakfast) mango, tater tots and vegetarian maize corn dogs(lunch), okra, tomatoes, pineapple, maize (dinner).

After exchanging the diets of both groups for two weeks with close supervision, the Americans were found to have less intestinal inflammation with increased production of butyrate which has been found to be protective agains colon cancer. Conversely, the Africans exhibited signs of worsened bowel inflammation and declined intestinal health overall.

Bottom line

Though it is a small study, it is quite provocative and provides compelling evidence for how quickly the environment in our gut can change when we change our diets (for better or for worse). It also reinforces previous studies that support eating more fiber and less animal protein/fat for better intestinal health!

Some personal thoughts on the study

What I find heartening and empowering about this study is how quickly the body is able to respond to one’s food choices (for better or worse). In just two weeks, the group who was now eating a more plant-based, high fiber diet showed evidence of decreased gut inflammation and increased production of cancer-preventing butyrate! The rapid responsiveness of our intestines to what we feed them is further evidence of our body’s resilience and incredible ability for transformation.

That being said, it is my experience that when people hear that they should change their diet to one that is “low fat” or “high fiber,” a lot of people just hear the word “boring.” Fiber for many people is synonymous with broccoli or groats, and not that there is anything wrong with those foods, but many crave other options.

Rather than focusing on “fiber” or “fat content,” I prefer to speak to my patients and clients about the pure pleasure and satiation that comes with eating a pineapple/mango chutney, or spiralized zucchini topped with a freshly made marinara sauce of tomatoes, basil and oregano and sprinkled with olives. And D.H. Lawrence devotes 2 pages to his poem on grapes. There is a total enjoyment in eating simple, fresh, ripe fruit. When we focus on this, the pleasure that comes from eating these whole, vibrant “garden” foods, there is an effortless movement towards eating more and more of them, and essentially “crowding out” the foods that cause dis-ease. And that’s a more palatable way, I think, of preventing colon cancer.