The Journey Of Food

2. The Journey Of Food

Food enters the body through the mouth and exits through the anus. In between, it undergoes digestion (from the mouth to the stomach), absorption (from the stomach to the small intestines), and elimination (from the large intestine, or colon, to the anus). In most cases, these three stages of food processing take place in a total of about twenty-four hours in a relatively healthy individual. This journey takes place in what is on the average over fifteen feet of a single connected tube from the mouth to the anus.

This fifteen feet of elasticized tubing (which includes the esophagus, stomach and intestines) is said to be continuous with the outside environment. That is, there is one entrance from the outside world to the food tube (the mouth) and one exit (the anus) with no other outlet inside the body proper.

Food in this tube (usually called the gastrointestinal tract) is technically considered to be outside the body. As food passes through this tube, it may be partially absorbed by the body. At any time, the food itself may be rushed back out through the mouth (vomiting) or quickly expelled through the anus (diarrhea).

This is the reason that man can seemingly eat anything. His digestive-absorptive-eliminative tract, or tube, actually holds the ingested food outside of the body proper. If a healthy person should eat harmful foods, they may be carried through the body to the nearest exit without actually being absorbed or entering into the body from this tube.

However, many individuals, through years of improper eating, have degraded the natural power of the body to expel unsuitable foods. Consequently, the body gradually starts to absorb noxious substances from foods which a healthy organism would reject outright.

Consider this example: If a young infant is given a swallow of strong coffee, he or she will probably vomit it back up or experience immediate diarrhea. This is because the gastrointestinal tract of a young child is still sensitive and strong enough to actively inhibit such substances from entering the body.

People who have been vegetarians for several months will often experience this reaction if they, should attempt to eat meat again. A healthy body will try to protect itself from harmful non-food items.

The gastrointestinal tube is the pathway all food must follow in its process of digestion and assimilation. What occurs along this path is discussed in the next sections of this lesson.

2.1 The Appropriation of Food

Appropriation is the making of something into one’s own. Appropriating foods, then, is the act of taking food into the body. The first step toward digestion and assimilation of food is the physical selection of food. This selection is guided primarily by visual and olfactory cues.

Our first contact with food is visual. Young children originally try to discover what is good to eat and what is not by sticking everything within their field of vision into their mouths. If it tastes good, it is food and is swallowed. If not, it is spit out. While effective, this is not the best way to choose food. A variety of items such as rocks, dirt, loose coins, and so forth are often swallowed by children in their exploring quest for suitable food.

Gradually, the child learns to recognize food items by sight. An orange is orange and is for eating, and a baseball is white and is for knocking over breakable items. Very quickly, children learn to recognize food by visual cues alone, and adults soon take this aspect of food appropriation for granted.

Visual appearance of food is an important part of the digestive process. People start to salivate at colorful pictures of food dishes. If the food is pretty and served in a visually pleasing manner the amount of digestive juices secreted is greater than if the food appears distasteful or if it is served in unpleasant surroundings.

The visual appeal of an apple hanging on a tree in an orchard is evident; that same apple stuck in the mouth of a roasted pig, however, does not raise the same expectations in the eater.

Food that is simply unfamiliar is often automatically rejected. Some people refuse to eat yellow tomatoes because they “look funny.” Thereby they may miss a wonderful taste sensation.

All of this may seem obvious, but it is often overlooked in the physiology of nutrition. The body begins to respond immediately when food is placed within the visual field. If the food itself or the surroundings within which it is presented are unappealing, then actual digestion and assimilation of the blood will be impaired. If, on the other Hand, food is artfully presented in a visually pleasing manner, digestion is enhanced.

This does not mean that a lot of artifice should be used in preparing food. On the contrary, if food is naturally attractive, such as fruits or vegetables, then a minimum of ‘stage dressing’ is required. Notice that advertisements for steaks and hamburgers prominently feature salad with vegetables, their attractive colors of red, green and yellow to contrast with the distastefully brown or black meat. Digestion, or lack of it, begins with the eyes.

2.2 Olfactory Cues

The nose is the next organ involved in the physiology of digestion. The fragrance of food stimulates the olfactory nerves, which in turn starts the salivation process. This does not mean, however, that food must be overwhelmingly ‘fragrant,’ as is the usual case with cooked foods and spices and onions.

Smelling food is actually a subtle experience that may require re-educating the sense of smell if it is jaded by over-seasoned cooked food. An apple gives a subtle bouquet of odors to whet the appetite. The smell of ripening bananas or a bowl of strawberries is more enjoyably overwhelming to the healthy individual than is the stench of onions and garlic piled upon burnt meat.

The eyes and the nose, then, are the first organs used in the process of digesting and assimilating food. It is important, therefore, that time be taken to appreciate and select food according to its appearance and smell.

2.3 Alimentation: From the Mouth to the Stomach

After food is chosen according to sight and smell, it is brought towards the mouth and saliva starts to secrete. The mouth is the first step in the digestion of food proper.

The digestion of food can be viewed as two concurrent processes: 1) Mechanical, or the actual movement of food as it is broken down into smaller particles; and 2) Chemical, or the splitting of food into its simple nutritive components. In the mouth, mechanical digestion is performed by the actions of the teeth and tongue, while the saliva furnishes the first step of chemical digestion.

2.4 The Mouth

The teeth perform the first mechanical operation of digestion. Food is first bitten by the incisor teeth at the front of the mouth. Then the canine teeth (next to the front teeth) shred the food into smaller parts as it is passed back to the bicuspids, which continue tearing it into smaller portions. Finally, the molar teeth (in the back of the mouth) finish the grinding and crushing of the food.

Chewing by the teeth increases the surface area of the food so that it may be more easily penetrated by the digestive enzymes. Chewing the food is a very important part of digestion. Not only does it break {he food down into more easily digestible…particles, but it also stimulates nervous impulses that cause the secretion of gastric juices, and thus prepare the digestive system for the food to be swallowed.

The teeth are very powerful. The front teeth, which tear and shred food, can exert a force of up to

80 pounds. while the grinding molars can apply 100 to 250 pounds of force against food particles!

At the same time that the teeth are doing their work, the tongue is performing the other aspect of mechanical digestion in the mouth by moving the food back and forth, from side to side and mixing it with the saliva.

The salivary glands help perform chemical digestion in the mouth. There are three pairs of salivary glands in the mouth. They continuously secrete saliva to keep the mouth from drying out. During the day, these glands produce from 1 to 1 1/2 quarts of saliva.

The saliva prepares the food for swallowing by lubricating it with mucin, which gives saliva its slippery characteristic. Imagine how hard it would be to swallow food “dry” without this natural lubrication.

The first digestive enzyme is also contained in the saliva. It is called ptyalin or amylase. This enzyme starts the digestion of starches in foods, Ptyalin helps convert starch to a sugar called maltose.

Since this enzyme is the major factor in starch digestion, all starchy foods should be chewed thoroughly and mixed well with saliva. Human beings, however, are not well adapted to eating starches, so the amount of starches in the diet should be restricted.

Saliva also has a solvent action upon food. It is only after the food is somewhat dissolved that it can be tasted.

In  addition to ptyalin, saliva has an enzyme called lysozyme that digests bacterial cell walls, thus killing certain microorganisms. Saliva also has a cleansing action as its constant flow helps to dissolve and remove food particles from the teeth.

After mechanical and chemical digestion has progressed to a certain point in the mouth, the tongue gathers the food together into a small ball and then elevates the mass of food back into the pharynx of the throat. This is the first stage of swallowing and the beginning of the food’s journey down to the stomach.

2.5 From Mouth to Stomach

After food rolls off the tongue, it is no longer under voluntary control. It is now moved through the system under the control of the involuntary nervous system. Short of self-induced vomiting, it is now up to the wisdom of the body to move the food as it sees fit.

After leaving the tongue, it will take about 8 seconds for the swallowed food to reach the stomach. Most of this time is spent traveling down a tube called the esophagus.

The food passes down this tube in a peristaltic (wave-like) motion. These peristaltic waves are strong enough so that even if suspended upside down, a person can swallow about a half-ounce of food and it will work its way against gravity into the stomach. This is why astronauts can eat in “free fall” or zero-gravity. This is also why they must eat in small sips or swallows, being careful not to take in over a half ounce of food per swallow.

Pure liquids can move down the esophagus in only one second, eight times faster than the peristaltic waves move the solid food.

2.6 The Stomach

The food passes from the esophagus into the stomach through an opening called the cardiac orifice. As soon as food enters the stomach, a hormone called gastrin is released into the bloodstream.

This hormone is carried to the gastric glands in the stomach which causes them to secrete digestive juices. These gastric juices help in the chemical digestion of the food, while the rhythmic contractions of the stomach contribute to the mechanical process of digestion.

The gastric juices in the stomach are secreted at the rate of two to three quarts per day. These juices contain primarily hydrochloric acid (HCl) and digestive enzymes.

The hydrochloric acid makes the stomach a very acid environment with a pH factor between 1.5 and 3.0 (as compared to pure lemon juice, with a pH factor of 2). This acid environment caused by the HCl secretions serves two, functions: 1) it acts as a denaturant in digestion of proteins; and 2) it kills small parasites that are often found in all foods.

Three primary enzymes are also present in the gastric juices. The first is pepsin, which aids in the hydrolysis of proteins. The pepsin enzyme begins breaking down complex proteins into their simpler forms. It does not actually split the proteins into amino acids (the end-product of protein digestion), but it prepares them for that process which occurs in the intestines. The pepsin enzyme works best in a fairly acid environment. An acid environment is also conducive to protein digestion.

The second enzyme is called lipase. This aids in the hydrolysis of fats. Lipase starts the digestion of fats by aiding their breakdown into glycerol and fatty acids. The lipase enzyme works best in a more neutral pH environment than does the pepsin enzyme.

The third enzyme, found only in the gastric juices of infants, is called rennin. Its primary function is the hydrolysis of milk proteins. Adults do not have the rennin enzyme in sufficient quantity to digest milk products. Consequently, the only time milk should be used in the diet is during infancy and young childhood. Even at these times, the only suitable milk is that from the lactating mother. Milk from cows, goats, etc. is not of the same composition as is mother’s milk and should not be consumed by humans of any age.

These three enzymes, along with the gastric juices, are mixed into the food by the mechanical actions of the stomach. The stomach contracts in waves at the rate of three per minute. The stomach has a capacity for holding up to two quarts of food in volume. When a person is fasting, the actual volume of his or her stomach may be less than two ounces.

The gastric juices mixed in by the contracting and relaxing stomach are initially stimulated by the thought, sight, smell and taste of the food. This occurs before any food has actually entered the stomach. These juices are sometimes called the “appetite juices”, and they may be suppressed if the food appears unappetizing, smells bad, or is eaten in an unpleasant environment.

Digestive secretions in the stomach are increased by attractive and well-liked foods as well as by a state of contentment and happiness. The secretions are decreased by large meals, large amounts of fat, poor chewing, poor appearance of food and negative emotions.

In the presence of intense pain, fear, or depression, gastric juices may be almost completely suppressed for up to twenty-four hours. This fact alone is reason enough not to eat when upset or feeling out of sorts.

The stomach empties at the slow rate of about 3/100 ounce for each peristaltic wave. At three waves per minute, it can take up to five hours for two pounds of food to leave the stomach.

The emptying time of the stomach also varies with the type of food present. Water and liquids leave the stomach most rapidly. Carbohydrates empty more quickly than proteins; proteins, in turn, leave the stomach more quickly than fats.

Within five minutes after fat enters the stomach, a hormone called enterogastrone enters the bloodstream and travels to the stomach, “this hormone inhibits the motion of the stomach and causes it to empty at a much slower rate.

Not all foods undergo the same digestive processes in the stomach, and not all foods leave the stomach at the same rate. Proteins digest in an acid environment, while fats need a neutral environment. Carbohydrates leave the stomach at a faster rate than proteins, and so on.

Even among the carbohydrates (fresh fruits and vegetables), digestion time may vary a great deal. Below is a chart listing the time that various foods remain in the stomach:

Food Minutes Held In Stomach
Parsley 75
Lemon 90
Grapes 105
Tomato 120
Carrot 135
Almond 150
Apple 165
Banana 180
Peanut 195
Eggplant 210
Persimmon 225
Turnip 240

Since different foods require different sets of environments in the stomach to digest properly, it is reasonable to assume that if these foods are put into the stomach at the same time, difficulties could occur. That is exactly what happens.

Consider the all-American cheeseburger. A bite of it might contain a starch (bread) a protein (meat), a fat (cheese), and an acid (tomato), what happens when a single bite of this hits the stomach?

The starchy bread was probably not chewed very thoroughly in the mouth and the starch-digesting enzyme had little chance to do its work. So, the bread reaches the stomach in an unprepared state. The meat will require a very acid environment to digest. This makes it difficult for the starch to digest, since acids are inimical to starch digestion. The fat in the cheese requires a more neutral environment than the meat protein to digest, and its fat content causes the stomach to slow its digestion. At the same time, the acids in the tomatoes interfere with the starch digestion of the bread.

In this single bite, there are over seven different types of food requiring four different sets of enzymes and digestive conditions, and all digest at different rates!

At best, such a conglomeration of food in the stomach will slow digestion down to the point of fermentation. This will lead to autointoxication. At worst, the food simply becomes half-digested and is pushed sluggishly through the system, releasing its poisons and gases throughout the body.

The same people who would never mix water, kerosene, or oil with their gasoline for their car will sit down to a meal and give their stomachs a mixture of mashed potatoes, steak, butter, and beer.

Fortunately, the stomach does not break down as fast as an abused automobile. But the stomach’s resilient quality causes people to think they are getting away with their dietary indiscretions.

If different foods are to be put into the stomach at the same meal, they should at least be of the same type that requires the same set of digestive conditions. Ideally, of course, only one food should be eaten at a meal to insure optimum digestion.

Since food combining is such an important area, it is covered in a separate lesson in this course.

2.7 The Small Intestine

The small intestine consists of about 9 feet of  inch tubing coiled in the abdomen. This tubing leads from the stomach to the large intestine. It is in the small intestine that most of the digestion and absorption of food occurs.

Food passes into the small intestine from the stomach by entering the duodenum. The duodenum is the smallest segment of the intestine, being only 8 inches long. Food travels through the small intestine by weak contracting waves of motion that propel the food toward the large intestine.

The other two segments of the small intestine are the jejunum, which is 3 feet long and connects the duodenum to the ileum, the final 3 feet of the small intestine.

The small intestine interior has many folds. Along the surfaces of these folds are tiny finger-like projections called villi.

The villi of the intestine move back and forth, like thousands of tiny tentacles, passing through the food as it is moved along the intestinal tract. The villi play an important role in the absorption of food from the small intestine.

Through the center of each villi is one or more fine white vessels called lacteals. The lacteals are part of the lymphatic system. Their principal function is probably the absorption of fat.

As food passes through the small intestine, it is taken up, or absorbed, by structures in the wall of the intestines, especially the villi, and is then secreted into the lacteals. Some of the digested food is absorbed by the numerous blood vessels that line the villi. This digested food directly enters the bloodstream.

As digestion progresses in the small intestine, portions of food are moving in large quantities into the capillaries of the intestinal villi. Blood from the intestines containing these products of digestion is collected in the portal vein, which is connected to the liver.

The liver removes the excess glucose from the blood (glucose being one of the end-products of digestion) and stores it as glycogen, to be used later in normalizing the blood-sugar level and for supplying energy. It also attempts to detoxify harmful elements in the food (such as pesticides), and regulates the level of nutrients available to the body.

The liver is one of the master organs in the body. It receives all the end-products of digestion. The bulk that remains behind after the vital elements are extracted by the villi in the intestine and sent to the liver is then pushed down toward the large intestine. Normally, most of the contents of the intestines have been absorbed by the time the food reaches the middle of the jejunum segment of the intestine, or about 3 feet along the 9 feet of tubing that makes up the small intestine.

The tone and motility of the small intestine is increased by foods served at room temperature, fibrous foods, and high-carbohydrate, low-fat foods. Movement is slowed by cold, dry, and high-fat foods.

2.8 The Large Intestine or Colon

The small intestine joins the colon in the region of the right groin. At this juncture is the ileo-cecal valve whose purpose is to control the speed of passage of substances from the small intestine and to prevent any wastes from returning to it from the large intestine. The ileo-cecal valve opens into the colon into a pouch known as the cecum, the first receptacle for waste residue.

At the tip of the cecum is the appendix. Due to the appendix’s position near the waste receptacle, toxins from a diet high in meat, heavy starches, etc. can contribute to its inflammation which may result in a condition known as appendicitis.

If a person suffering from appendicitis simply abstains from all food (fasting), then thebody can conduct its housecleaning and clear up the inflammation without removal of the appendix.

From the cecum, the large intestine ascends on the right side to the middle of the abdomen, then crosses to the left side and descends again. These three sections are called the ascending, transverse and descending colons.

One of the chief functions of the colon is the reabsorption of much of the water used in the digestive process. If all the water in which the digestive enzymes were secreted was lost in the feces, man would have to drink liquids continually.

If too much water is expelled with the feces, then a condition known as diarrhea exists. Diarrhea happens because of an irritation in the stomach and small intestine due to unsuitable food or inflammation. In this case, the colon expels all of its waste residue upon entry without holding it for water reabsorption.

On the other hand, if the waste material moves too slowly through the colon, then excessive water is reabsorbed and the feces become hardened. This is called constipation.

Waste material may move too slowly through the colon for a number of reasons. Perhaps the most usual reason is that peristaltic nerves are paralyzed by toxicity from decaying foodstuffs.

Another reason for the slow movement of waste through the colon is that the passageway has become very small due to poor tone or to hardened feces clogging the intestinal walls.

After several years on a conventional low-fiber diet, the average adult continually carries around about ten to twenty pounds of fecal material on the colon walls. In many instances, the distended abdomens in overweight individuals are not due so much to fat as they are to accumulation of feces over a period of years. Autopsies on much individuals have sometimes revealed over fifty pounds of fecal material in the body!

When the body is abused by the modern diet, the colon often suffers the most. Fortunately, a diet high in natural fiber (that is, raw fruits and vegetables) can greatly aid the body in restoring the health of the intestines.

The last portion of the large intestine is the rectum. This segment serves as a storage chamber for the feces until defecation. The feces are eliminated from the rectum through an opening called the anus.

And so the journey of food through the body is completed. Many healthy individuals process the food from the mouth to the anus in about sixteen to twenty-four hours. Most adults eating a conventional diet, however, generally take from forty-eight to seventy-two hours for their food to complete its journey. Much of this added delay is due to incompatible food combinations and lack of colon vitality.

Now that we’ve followed the bodily journey of food from its beginning to end through the gastro-intestinal tract and learned about some of the physiological processes that accompany this journey, we will proceed to determine an optimum diet, one that promotes digestive efficiency and general well-being.

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