The total length of the intestinal system from one end to the other is around eight to 10 meters. Food ingested at the mouth takes a variable time to pass through the entire tract. This is termed the transit time, and may vary between 20 and 50 hours. In recent times, more attention is being paid to the transit time, for it is believed by many researchers and doctors that this may play a very significant part in a large number of intestinal disorders. The longer the transit time, the longer food residue and toxic products remain in contact with the bowel lining, it is argued. This means that certain toxins may play a part in causing various bowel disorders.
For example, toxins called carcinogens or irritants are believed to irritate the cells of the lining of the large bowel and may, over a long period of time, initiate cancer of the large bowel, a fairly common occurrence in Western populations. Therefore, the longer the irritants are in contact with these cells, the greater is the risk of these disorders developing with the passage of time.
Similarly, the longer the transit time, the greater the degree of pressure that builds up in the bowel. In time, this may be responsible for small pockets occurring in the bowel walls. This is called diverticulitis, and its origin has baffled doctors for decades.
Reduced transit time seems that all this may be achieved by the simple expedient of adding more crude fiber to the daily food intake. In practical terms, this means adding unprocessed bran or other forms of natural fiber to the daily diet—a relatively simple process, and one that seems to be having an extremely beneficial effect on those following the system.
When food is eaten, the teeth and oral cavity are geared to break large food particles into smaller ones that may be swallowed with ease. The food is mixed with saliva, which contains weak chemicals that put the process of digestion into operation. From the oral cavity, the food slips into the food tube called the esophagus.
This tube has a small valve at the far end, called the cardiac valve. This opens at regular intervals, enabling the food mass (called a bolus) to enter the stomach. The stomach is merely a dilated portion of the digestive system. It is lined with specialized cells that actively secrete a powerful acid (hydrochloric acid) and certain digestive juices. Here digestion of the food really gets under way.
The food particles are reduced into still smaller particles, until a thick fluid volume is produced. From here, the food passes through another valve, called the pylorus, into the next part of the intestinal (or digestive or bowel) system, called the duodenum. Here there is a prolongation and intensification of the digestive process. Gradually the duodenum empties the food into the next part, the so-called small intestinal system. This is the lengthy bowel system, and here digestion continues. This is also where the final ingredients of the broken-clown food are actively absorbed by the cells lining the bowel wall and pass into the bloodstream.