The GI tract has a surface area 200 times greater than our skin and is exposed to the external environment via the food we eat. Within your lifetime, you will consume between 30-50 tons of food. All of this food is part of the external and potentially harmful environment. It is the responsibility of the GI tract to break down this food, absorb the beneficial nutrients and, at the same time, prevent harmful compounds from entering the blood stream. All of these functions need to be carried out efficiently to maintain optimal health. The GI tract has four main functions, which can be referred to as The Pillars of GI Health. These four pillars are: Digestion, Elimination, Microflora Balance and Gut Integrity. They are called pillars because it is upon these and their inter-relationship that the health of the GI system…and consequently the whole body…is supported.

I. Digestion: The main function of the GI tract is to digest and absorb the foods you eat. Ultimately food provides the energy for every cell in the body,. Poor digestion and absorption of key nutrients will result in low energy, sluggish metabolism, mental fog, fatigue and increased susceptibility to chronic illnesses. Proper digestion allows the appropriate types and amounts of bacteria to flourish within the GI tract to assist in digestion and vitamin production processes.

II. Elimination: The process of elimination is just as important as digestion, and it is vital four our well-being. Elimination involves removing the unusable portions of the food you eat as well as eliminating toxic waste products from biochemical reactions taking place in the cells. It is essential that both of these types of wastes be completely eliminated from the body, otherwise toxins build up and are stored in various tissues.

III. Microflora Balance: A small ecosystem that has a very important role in your health and well-being. This ecosystem is composed of more than 100 trillion microscopic organisms (microbes), collectively called the “microflora”, that live in the GI tract. The microflora is composed of more than 400 different strains of beneficial yeast, bacteria, and microorganisms that grow in the intestines, and is one of the most metabolically active systems in your body. Microflora helps maintain healthy and functional digestions and absorption in the GI tract. These organisms also regulate immune function and blood sugar levels, assist in vitamin production and manufacture essential nutrients such as butyrate, which is a source of energy for the gut lining. It is important to keep the beneficial flora in balance and in plentiful supply to help regulate the digestive system and prevent gastrointestinal illnesses.

IV. Gut Integrity: The GI tract is the largest protective layer of the body, serving as a barrier between our internal body and the external world. It covers an area the size of a tennis court-more than 200 times greater than the surface area of the skin. It is a critical function of the mucosal membrane (the membrane lining the gut) to allow nutrients to pass into the body while preventing passage of all the harmful substances that move through the gut. If the mucosal membrane is not maintained, the intestinal barrier becomes permeable to a number of harmful substances that trigger a host of immune-related responses commonly linked to numerous GI disorders, such as Crohn’s disease, celiac disease and food allergies. In fact, the GI tract houses a majority of the immune system network in the body-about 70% is closely related to the GI tract and plays a critical role in gut integrity. The gut mucosa is the home for the microfloral ecosystem.

The role of healthy gut microbes

Few people realize that they carry nearly 100 trillion living bacteria within their GI tract, resulting in 10 times more bacterial cells than human cells in your body…who is hosting who here?!. Proper understanding and management of these organisms within the gut is required to attain maximum health. Here is what they do when they are properly balanced:

• Protect against intruders: When our commensal bacteria (the unique blend of organisms suited to each individual) thrive appropriately within our gut, they naturally displace intruding pathogens by competing for available nutrients. They bind to and inhabit specific sites along the gut wall, producing chemicals that can kill harmful bacteria and yeast particles. This activity prevents would be pathogens from becoming noticed by us or our immune system.
• Help maintain immune and barrier functions: Almost 70% of our entire immune system is concentrated in our GI tract. Scientists believe this is because the gut is our most vulnerable contact with the outside world (remember that 50 tons of food). As it turns out, our microflora plays a special role in training the immune system to respond appropriately throughout our lifetime. If improperly trained, the immune system may overreact, causing an unnecessary allergic or inflammatory response to harmless threats. Also, some bacteria secrete substances that help tighten the junctions between intestinal cells (preventing leaky gut) and stimulate the formation of important antibodies (secretory IgA) into the gut from adjacent immune cells.
• Act as an important metabolic “organ”: The trillions of bacterial cells in the body are actively metabolizing food particles, including breaking down some potential carcinogens. Several of these microbes act to ferment specific kinds of fibers (these are called fermentable fibers) to produce short chain fatty acids that are vital to promoting healthy colon cell growth, Also, several important vitamins are synthesized directly by our microflora.

To summarize and get outright geeky and scientific, our healthy gut microbes have:

• Protective functions

o Pathogen displacement

o Nutrient competition

o Receptor competition

o Production of anti-microbial factors like bacteriocins and lactic acids

• Structural functions

o Barrier fortification

o Induction of IgA

o Apical tightening of Tight Junctions

o Immune system development

• Metabolic functions

o Control IEC differentiation and proliferation

o Metabolize dietary carcinogens

o Synthesize vitamins like biotin and folate

o Ferment non digestible dietary residue and endogenous epithelial derived mucus

o Ion absorption

o Salvage of energy

All of these important health-maintaining activities are put in jeopardy when the delicate balance of the ecosystem in the GI tract is disturbed. This imbalance is called dysbiosis. Next week we will talk about how this finely tuned system can run so amuck!