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Your gut (your body's gastrointestinal tract) is one of the most important yet often overlooked keys to good health. To understand why, let's take a look at your GI tract and the important functions it performs.

Your body's gastrointestinal (GI) tract consists of hollow tube known as the alimentary canal. The alimentary canal is between 26 and 32 feet long. It begins at your mouth and ends at your anus, and also includes the pharynx, esophagus, stomach, small intestine and large intestines, and the rectum.

One of the main functions of the GI tract is to provide your body with the nutrients it requires to maintain its health. The GI tract is assisted in this digestive process by the liver, gallbladder, and pancreas. Additionally, and of equal importance, the GI tract is also responsible for preventing unhealthy substances from being absorbed into your body. These interrelated functions are accomplished in three ways: the movement of food along the alimentary canal that occurs as muscles in the GI tract push food particles forward; the secretion of gastric juices by the stomach, pancreas, and liver, which enables food particles to be broken down; and the absorption of the fluids and nutrients contained in food by the small and large intestines.

A Tour of Your Digestive System

The process of digestion begins from the moment that you start eating food. As you start chewing, your body's saliva and parotid glands secrete enzymes that begin the process of breaking down food. Then, as you swallow, the food moves rapidly though your esophagus to enter your stomach. Food remains in the stomach until it is further broken down, liquefied, and processed as it comes in contact with additional enzymes and gastric juices such as hydrochloric acid, which is necessary for the breakdown of proteins into smaller sized particles known as polypeptides that are then used by your body to perform a wide variety of tasks.

Once food passes out of the stomach, it enters the small intestine. There, food particles are further broken down by a combination of digestive enzymes secreted by the pancreas and bile secreted by the liver. On average, an adult's small intestine is over 20 feet long. During the first four to six hours that food passes through it, most of the nutrients and fluids the food contains are assimilated as food particles through the first 40 inches of the small intestine. This is accomplished by a "work force" of tiny, hair-like organisms that line the intestinal wall, called microvilli. The microvilli sift through food particles and soak up various nutrients such as carbohydrates, fats, minerals, proteins, and vitamins, passing them through the intestinal walls and into the bloodstream, where they are transported throughout your body, to be used where they are most needed. At the same time, the microvilli also act as the front line of the digestive defense system, preventing toxic substances from being absorbed into the bloodstream as well.

Whatever food particles remain after this process then pass through the remaining 20 or so feet of the small intestine, which continues the absorption process, primarily of bile salts, water, electrolytes, and vitamin B12. Any leftover food particles and fluids are then passed into the large intestine, where they are assimilated, while undigested food content, toxins, and waste byproducts are prepared for elimination.

Your Body's "Second Brain"

In addition to digesting foods and liquids and eliminating wastes and toxins, the gastrointestinal tract is also home to your body's "second brain," which is a very apt description of the enteric nervous system that is located in the linings of the esophagus, stomach, and small and large intestines. Research conducted in the last few decades indicates that that the enteric nervous system acts as a single entity, brimming with neurotransmitter proteins. (Neurotransmitters transmit nerve impulses from nerve cells to other cells and are essential for your body to be able to properly perform its many functions.) These proteins are produced by cells that are identical to those found in the brain, and research has shown that this complex circuitry enables this "GI brain" mimic actual brain function in that it is able to act independently, learning, remembering, and producing so-called "gut feelings."

All of these processes are part of the overall operation of your body's autonomic nervous system (ANS). The nerve endings that are attached linings of the GI tract provide nerve impulses that stimulate the operation of the various organs and glands within your body. The type of stimulation that the ANS is able to provide to your organs and glands is a direct reflection of the health of your GI tract.

How Disease Occurs in the GI Tract

Healthy functioning of the GI tract depends in large part on the health of the gastrointestinal lining. The health of the GI lining, or intestinal walls, depends in turn on a coating of "friendly" bacteria. Between 300 and 500 distinct species of bacteria exist within the GI tract. All told, approximately 100 trillion such bacteria inhabit the GI tract. This equates to ten bacteria for every cell in the body.

These friendly bacteria, also known as flora, form a protective shield that covers the intestinal walls and prevents harmful and damaging substances such as toxins and "non-friendly" bacteria, viruses, and other microorganisms, from passing through the GI lining into the body's bloodstream. At the same time, these friendly flora play an integral role in enabling vital nutrients and fluids to pass through the GI lining into the body.

So long as the friendly flora are present in sufficient numbers and remain unharmed, the overall functioning of the GI tract remains intact as well. However, if these flora are subjected to repeated exposure to harmful substances, then the white blood cells within the microvilli that also line the GI tract go into attack mode. In cases in which healthy flora are temporarily exposed to harmful substances, the white blood cells are soon able to resolve the problem by attacking and eliminating these substances. But when chronic exposure to such substances occurs, the effort of the white blood cells to dispose of them can cause the lining of the GI tract to become irritated and inflamed.

This ongoing assault of harmful substances, combined with the irritation and inflammation, results in a breech in the defensive capacities of the friendly flora, making the intestinal walls increasingly permeable so that toxins, abnormal proteins, and other harmful substances now find themselves able to pass through the walls into the bloodstream. In laypeople's terms, this is known as "leaky gut syndrome."

If this process is allowed to continue unchecked, the body becomes overburdened with growing numbers of harmful substances, setting the stage for disease to occur, first within the GI tract itself, and then, potentially, in other areas of the body. During this process, healthy bacteria are forced to contend with unhealthy bacteria, leading to a condition known as dysbiosis, which is characterized by the proliferation of harmful flora from the lower colon, where they are normally kept in check by friendly bacteria, into other areas of the GI tract and into the bloodstream. In addition, further damage is caused by the spread of free radicals that are produced as a side effect of the chronic inflammation besieging the GI tract, and the overall functioning of the GI tract continues to be diminished, resulting in impaired digestion and absorption of essential nutrients. Eventually, this creates a vicious circle in which the body is not only under attack from within the GI tract, but also unable to mount an effective defense because it is no longer able to obtain sufficient nutrients.

Not only is the situation described above very serious, it is also one that in recent decades has affected an ever-growing section of the American public, as well as many people in other Western nations. Today, this problem is so severe that the social, medical, and economic costs of gastrointestinal problems and related disease account for a significant portion of our nation's annual $2 trillion health care costs.

Up to 100 million Americans suffer from some type of digestive diseases and the estimated lost work, lost wages, and medical costs comes to over $50 billion per year. Health statistics also show that more Americans are hospitalized due to diseases of the intestinal tract than for any other group of disorders.

In my next article, I will show you how you can avoid being a part of such grim statistics. And I'll also share self-care steps you can take to improve the health of your gut and, in doing so, improve and maintain your overall health as well.

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