We have established a symbiosis with our good gut bacteria, but we are not holding our end of the bargain.
If you look at the classics-topics that are often cited in scientific nutrition books-the first paper of the glycemic index takes the tenth place, which has been cited more than a thousand times. Learning about fruits, vegetables, and cancer prevention comes in at number seven. But hitting the top four, cited more than 2,000 times: “Dietary Modulation of Human Colonic Microbiota: Introducing a Concept for Therapeutic Medicine.”
As I discuss in my video How to Keep Your Microbiome Healthy with Prebiotic Foodsprebiotics are food components that feed and nourish the good bacteria in our gut, such as fiber and resistant starch. Eating high-fiber plant foods is often “a good foundation for a prebiotic-rich diet.”
For a long time, fiber was thought of as just an undigested part of food, known only for bulking up stool and keeping the bowels regular. Then the researchers found a number of receptors in the body that the fiber-breakdown products fit into like a key. We feed our good bacteria with fiber, and they feed back, consuming fiber and making short-chain fatty acids. These fatty acids enter our bloodstream and enter these receptors that are expressed in the cells of the immune system, often having a direct anti-inflammatory effect.
Therefore, the reason behind the decrease in systemic inflammation in plant-based eaters may not simply be from the abundance of anti-inflammatory molecules in plant foods or the avoidance of pro-inflammatory molecules in animal foods, but from the production of anti-inflammatory molecules from scratch by our good gut bugs when we feed them. Just to give you an idea of how protective a fiber-rich diet can be, those who randomly sought advice on eating fiber-rich plant foods during cancer radiation therapy not only experienced reduced toxicity during treatment—the benefits continued even a full year later.
Indeed, the benefits of fiber are supported by over a century of research. Prospective studies show “significant reductions” in deaths from all causes combined, including “total cancer deaths, total cardiovascular disease deaths, stroke, and colorectal, breast, and throat cancers.” Also, in terms of protection against heart attack and stroke, type 2 diabetes, and cancer, a dose-response relationship suggests that the more fiber, the better. Therefore, at least, fiber intake should not be less than 25 to 29 grams per day; A higher diet can provide additional benefits. However, the average American consumes only 16 grams of fiber per day.
We have interacted with gut bacteria for thousands of years, relying on our good gut bacteria in a kind of symbiosis to digest fiber and produce short-chain fatty acids and even some vitamins. However we do not hold up our end of the bargain. We should provide 100 grams or more of fiber per day, and not much more than 16 grams. The easiest solution to correct this lack of dietary fiber is to encourage the consumption of plant-based foods that are rich in fiber.
Doctor’s Note
A hundred grams of fiber a day?! Check it out Paleopoo: What We Can Learn from Fossilized Feces.
Also, to find out more about prebiotics, see Prebiotics: Tending to Our Inner Garden.
