Our digestive system involves Four major areas where the food we eat is broken down into products that our body can use. The process starts in the mouth where the food is mechanically broken down, infused with the enzymes contained in saliva and passed down the esophagus to the stomach. In the stomach the food is massaged in an acid bath and treated with more enzymes that start the process of decomposition. Once the food is partially broken down it gradually passes through to the duodenum where it is treated with pancreatic fluid and on into the small intestine. Digestion is largely completed in the small intestine through the addition of more enzymes and further agitation. About 95% the nutrients in the food we eat are absorbed through the wall of the small intestine into the lymphatic system.
The material that cannot be broken down in our stomach and small intestine falls into the general category of complex carbohydrates (poly saccharides or dietary fiber) and this is passed along to the large intestine where our microbiome takes over. Our microbiome uses a team process to break down these complex carbohydrates. Depending on the type of dietary fiber involved special “keystone” bacteria start a fermentation process that produces several byproducts that can then be digested by other members of the community.
As the gut bacteria feed on the dietary fiber they produce a variety of short chain fatty acids (SCFAs) like acetic acid, propionic acid and butyric acid. These SCFAs provide a small additional calorie boost to our body but are also a critical input to many functions that are critical to our health. For example, SCFAs boost our ability to absorb calcium, magnesium, iron and vitamin K. Other microbiome produced compounds help our bodies to fight inflammation and even regulate our disposition and sense of well being. Finally, a group of microbiome produced compounds are important in maintaining the cells and mucous membrane that line the gut and act as a dynamic barrier between the bacteria in our gut and the rest of our body.
Because there are millions of bacteria in our gut and those bacteria interact in ways that are, at this point, almost impossible to determine, we can only guess at the exact chemical interactions that go on in the microbiome’s digestive process. However, we know that the byproducts produced by a well nourished and diverse microbiome are important to our physical and mental health and that an under-nourished and a stressed microbiome can be the source of serious physical and mental health problems. The study of the microbiome and its role in our physical and mental health is a subject of major scientific research around the world. Clearly, in the future, we will all benefit from a better understanding of how the microbiome impacts our health. However, there is already enough evidence to make it clear that cultivating a diverse and well nourished microbiome offers enough benefits that we need to make the lifestyle and dietary changes required to produce that result.
The list of foods that support a healthy microbiome start with the fruits and vegetables that we have been told “are good for us” since we were children. Fruits, nuts and whole grains are the most available and generally the most palatable items on the list. If we don’t get the recommended 25-35 Grams of daily dietary fiber from those foods then there are high powered foods that can help to make up the difference. These include Farro, Chia, and a variety of other grains and seeds that can add a high fiber boost to other foods. Finally, there are commercial supplements containing Psylium and other complex carbohydrates that can provide an extra dietary fiber boost. While it is likely that there are “good, better and best” fibers, my reading indicates that all of those values are much less important than a diet that regularly provides the microbiome with enough fiber to keep it healthy. An occasional “fiber binge” does our microbiome no more good than an occasional square meal does for the rest of our metabolism. The key is to adopt a diet that feeds both of our digestive systems what they need every day.