The human intestine maintains within its inner cavity a complex, crowded environment of food remnants and microbial organisms (called “the intestinal flora”) from which the body derives nourishment and against which the body must be protected. The relationship between the human host and her army of microbes is described by the Greek word, symbiosis, which means “living together”. When symbiosis benefits both parties, it is called mutualism. When symbiosis becomes harmful, it is called dysbiosis.
The first line of protection against dysbiosis and intestinal toxicity is strict control of intestinal permeability, the ability of the gut to allow some substances to pass through its walls while denying access to others. The healthy gut selectively absorbs nutrients and seals out those components of the normal internal milieu which are most likely to cause harm, except for a small sampling which it uses to educate and strengthen its mechanisms of immunity and detoxification.
Bacteria form the largest segment of the intestinal flora. The number of bacteria in the large bowel (about a hundred trillion) exceeds the number of cells in the human body. Intestinal bacteria perform some useful functions, so that our relationship with them is normally one of mutual benefit. They synthesize half a dozen vitamins, supplementing those which are obtained from food. They convert dietary fibre–that part of food which humans cannot digest–into small fatty acids which nourish the cells of the large intestine. They degrade dietary toxins like methyl mercury making them less harmful to the body. They crowd out pathogenic bacteria like Salmonella, decreasing the risk of food poisoning. They stimulate the development of a vigorous immune response. Four-fifths of the body’s immune system is located in the lining of the small intestine.
Bacteria are dangerous tenants, however, so that dysbiosis is a common problem. As powerful chemical factories, bacteria not only make vitamins and destroy toxins, but also destroy vitamins and make toxins. Bacterial enzymes can inactivate human digestive enzymes and convert human bile or components of food into chemicals which promote the development of cancer. Some by-products of bacterial enzyme activity, like ammonia, hinder normal brain function. When absorbed into the body, they must be removed by the liver. People whose livers fail this task, because of conditions like cirrhosis, develop progressive neurologic dysfunction resulting in coma and death. For them, the administration of antibiotics which slow the production of nerve toxins by intestinal bacteria can be life saving.
The immune reactions provoked by normal intestinal bacteria may be harmful rather than helpful. Inflammatory diseases of the bowel, including ulcerative colitis and Crohn’s disease (ileitis), and several types of arthritis have been linked to aberrant immune responses provoked by intestinal bacteria. Two types of aberrancy have been described. First, intestinal bacteria contain proteins which look to the immune system very much like human proteins; they confuse the immune system and may fool the body into attacking itself. Second, fragments of dead bacteria may leak into the wall of the intestine or into the blood stream due to a breakdown in the mechanisms which regulate intestinal permeability. Circulating through the body, bacterial debris is deposited in tissues such as joints, provoking an attack on those tissues by an immune system trying to remove the foreign material.
Unlike bacteria, parasites appear to serve no useful function. The part of the immune system which they stimulate does not strengthen the organism to resist serious infection; instead it contributes to allergic reactions, so that parasitic infection increases allergic tendencies.
Our digestive system is perhaps the most significant system in terms of its importance to us. It is simply not possible to live and continue growing if we cannot digest and assimilate the food we take in. It has also been labelled the “brain” of the body. In Oriental Medicine, the abdominal area which houses the Hara for the Japanese and the Tan Tien for the Chinese is the reservoir of life force and vitality. It is also our early warning system. When we are feeling a little under the weather, we often feel queasy when we think of food. When we are feeling nervous and agitated, we say we have butterflies in our stomach.
Most literature on detoxification refers to liver enzymes, as the liver is the site of the majority of detoxification activity for both endogenous and exogenous compounds. However, the first contact the body makes with the majority of xenobiotics is the gastrointestinal tract. Over the course of a lifetime, the gastrointestinal tract processes more than 25 tons of food, which represents the largest load of antigens and xenobiotics confronting the human body. Furthermore, since most drugs are consumed orally, the gastrointestinal tract is also the first contact with many drugs. It is not surprising, then, that the gastrointestinal tract has developed a complex set of physical and biochemical systems to manage this load of exogenous compounds.
Several factors influence how much of a chemical ends up in the system, requiring detoxification by the liver. The gastrointestinal tract initially provides a physical barrier to exogenous components. As previously discussed, the gastrointestinal tract is the second major site in the body for detoxification. Detoxification enzymes such as Cyp3A4 and the antiporter activities have been found in high concentrations at the tip of villi in the intestine. Adequate first pass metabolism of xenobiotics by the gastrointestinal tract requires integrity of the gut mucosa. Compromised barrier function of the mucosa will easily allow xenobiotics to transit into the circulation without opportunity for detoxification. Therefore, support for healthy gut mucosa is instrumental in decreasing toxic load.
In the last 20 years of practice, I have found all allergies and complex chronic disease have their origins in some kind of gut dysfunction. Keep your gut healthy. For the last twenty years I have been helping people have healthier “guts”.