Over the pastfew weeks, I have written about two important roles that fiber plays in our health: improving our blood sugar and weight management, and regulating cholesterol.
Another crucial role of dietary fiber is feeding and optimizing our microbiome (gut bugs) in order to keep our immune system healthy and primed for action against pathogens and cancer cells.
When undigested fiber arrives in our colon, our microbiome (gut bugs) digest it. They produce a multitude of products that are essential to our health especially to the immune cells in the digestive tract.
Our digestive tract contains 70% of our immune cells! These cells are called gut associated lymphoid tissue (GALT). This tissue must learn to differentiate nutrients from pathogens – what to let in and what to keep out.
How the immune cells and microbiome interact to stimulate immune health is not exactly known. Research shows in animal models that immune information molecules called cytokines are higher after a high fiber meal. One thing we know is that the microbiome excretes a short chain fatty acid called butyrate that our cells use as fuel. This fuel helps the cells produce more mucous which is a barrier to bacteria infiltration. The fuel probably also allows the tract to constantly maintain the tight barrier to intruders. Ultimately, our system is better at fighting infections but also at recognizing our own cells and not evolving into auto-immune problems or allergies. Our immune system also remains sharp so that it can recognize cancer cells and eradicate them before they take hold.
With multiple courses of antibiotics and a low fiber diet – many of us have a less than optimal microbiome – diversity is critical. The best way to improve this situation is to eat more gut bug food – fiber!
We should be aiming at getting a minimum of 25 – 38 grams of fiber and the average Canadian consumes only 15 grams. Healthy indigenous diets may have 70 grams of fiber!
How do you get more fiber?
Eat a wide variety of vegetables, beans, fruits, whole grains and nuts and seeds.
If you want to add fiber to your diet in the form of supplements (powders, capsules), here are some ideas:
– Psyllium husk or seeds – I like this source because it’s inexpensive
– Glucomannan from konjac root
– Beta glucan from a variety of sources including oats – It is also being studied for immune modulating effects (similar to medicinal mushrooms)