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= Lesson 20 - The Physiology Of Digestion =

= Lesson 20 - The Physiology Of Digestion =

It has often been said: “You are what you eat.” More appropriately, this should prob- ably be: “You are what you digest and assimilate.”

It has often been said: “You are what you eat.” More appropriately, this should prob- ably be: “You are what you digest and assimilate.”

Consequently, most of what man eats is for naught, because much of the food eaten by the average human being is totally unsuitable for his digestive physiology. If we want to understand what foods are appropriate for man to eat, we must first understand the physiology of digestion and assimilation. We need to know how our body acts upon the food we eat. When we understand the principles of nutritional physiology, we can then determine the natural diet for man.

Consequently, most of what man eats is for naught, because much of the food eaten by the average human being is totally unsuitable for his digestive physiology. If we want to understand what foods are appropriate for man to eat, we must first understand the physiology of digestion and assimilation. We need to know how our body acts upon the food we eat. When we understand the principles of nutritional physiology, we can then determine the natural diet for man.

20.1.1 What is Nutrition?

=== What is Nutrition? ===

 

Dr. Herbert M. Shelton gives us this definition of nutrition: “It is the sum of all processes by which raw materials (foodstuffs) are transformed into living structure and prepared for use by the body.”

Dr. Herbert M. Shelton gives us this definition of nutrition: “It is the sum of all processes by which raw materials (foodstuffs) are transformed into living structure and prepared for use by the body.”

Nutrition is the physiological processes the body conducts as it transforms food into material for its own growth and maintenance. This lesson discusses these processes in the order that they occur in the body as food is appropriated, digested, assimilated and finally eliminated from the body.

Nutrition is the physiological processes the body conducts as it transforms food into material for its own growth and maintenance. This lesson discusses these processes in the order that they occur in the body as food is appropriated, digested, assimilated and finally eliminated from the body.

20.2. The Journey Of Food

== 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.

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.

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

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

20.2.1 The Appropriation of Food

=== 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.

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.

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 yel- low to contrast with the distastefully brown or black meat. Digestion, or lack of it, be- gins with the eyes.

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 yel- low to contrast with the distastefully brown or black meat. Digestion, or lack of it, be- gins with the eyes.

20.2.2 Olfactory Cues

=== 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.

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.

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.

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.

20.2.3 Alimentation: From the Mouth to the Stomach

=== 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.

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) Chemi- cal, or the splitting of food into its simple nutritive components. In the mouth, mechan- ical digestion is performed by the actions of the teeth and tongue, while the saliva fur- nishes the first step of chemical digestion.

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) Chemi- cal, or the splitting of food into its simple nutritive components. In the mouth, mechan- ical digestion is performed by the actions of the teeth and tongue, while the saliva fur- nishes the first step of chemical digestion.

20.2.4 The Mouth

=== 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.

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.

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.

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.

20.2.5 From Mouth to Stomach

=== 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 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.

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

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

20.2.6 The Stomach

=== 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.

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.

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

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

20.2.7 The Small Intestine

=== 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.

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.

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.

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.

20.2.8 The Large Intestine or Colon

=== 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 intes- tine. The ileo-cecal valve opens into the colon into a pouch known as the cecum, the first receptacle for waste residue.

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 intes- tine. The ileo-cecal valve opens into the colon into a pouch known as the cecum, the first receptacle for waste residue.

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.

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.

20.3. The Physiological Determinants of the Optimum Diet

== The Physiological Determinants of the Optimum Diet ==

 

A wealth of information exists about the physiology of food digestion and absorption. Unfortunately, the science of nutrition has often depended upon “rat experiments” and artificially induced deficiencies, rather than upon the true needs of humans, to de- termine dietary requirements.

 

 

 

 

A wealth of information exists about the physiology of food digestion and absorp- tion. Unfortunately, the science of nutrition has often depended upon “rat experiments” and artificially induced deficiencies, rather than upon the true needs of humans, to de- termine dietary requirements.

A more reasonable approach to determining the true dietary nature of humans is to study human anatomy and physiology. By studying human physiological nature, certain characteristics of the proper diet can be deduced that are in accordance with the inher- ent nature and anatomical makeup of humankind. This approach does not depend upon contrived experiments, nor is it already biased by what the majority of people believe a traditional diet should be. Instead, human physical capabilities and predispositions are the chief factors in determining true dietary needs.

A more reasonable approach to determining the true dietary nature of humans is to study human anatomy and physiology. By studying human physiological nature, certain characteristics of the proper diet can be deduced that are in accordance with the inher- ent nature and anatomical makeup of humankind. This approach does not depend upon contrived experiments, nor is it already biased by what the majority of people believe a traditional diet should be. Instead, human physical capabilities and predispositions are the chief factors in determining true dietary needs.

20.3.1 Food Appropriation

=== Food Appropriation ===

 

The diet of most animals is largely determined by their food-gathering equipment. The long neck of the giraffe enables him to feed upon the foliage of trees. The teeth and claws of the lion are its means of killing and rending animals for its meals. The eagle’s eyesight and power of flight make this creature a formidable predator of ground rodents.

The diet of most animals is largely determined by their food-gathering equipment. The long neck of the giraffe enables him to feed upon the foliage of trees. The teeth and claws of the lion are its means of killing and rending animals for its meals. The eagle’s eyesight and power of flight make this creature a formidable predator of ground rodents.

So, it is salient to ask, how are you physiologically equipped to obtain your food? You have no sharp claws for tearing, no pointed teeth for slashing, nor are your eyes or sense of smell very well developed for hunting. You cannot run fast enough to chase down your prey nor can you naturally swoop through the sky or dive deep into the ocean.

So, it is salient to ask, how are you physiologically equipped to obtain your food? You have no sharp claws for tearing, no pointed teeth for slashing, nor are your eyes or sense of smell very well developed for hunting. You cannot run fast enough to chase down your prey nor can you naturally swoop through the sky or dive deep into the ocean.

You do have a marvelous set of fingers with an oposable thumb and limbs for reach- ing and climbing. Actually your food-gathering capabilities are very similar to the chim- panzee’s!

You do have a marvelous set of fingers with an opposable thumb and limbs for reach- ing and climbing. Actually your food-gathering capabilities are very similar to the chimpanzee’s!

Only man can plant and harvest. He can peel oranges and bananas and pick berries and grapes. He can climb the trees for fruits or gather the vegetables from the ground. Of all the creatures on the earth, man is most ideal for being a gardener and caretaker of the plants and trees.

Only man can plant and harvest. He can peel oranges and bananas and pick berries and grapes. He can climb the trees for fruits or gather the vegetables from the ground. Of all the creatures on the earth, man is most ideal for being a gardener and caretaker of the plants and trees.

Man’s hands set him apart from the other animals in his food-gathering capabilities. Man appropriates his food by picking fruits from trees or by planting vegetables. It is the hands of man that are used to obtain his food, and the most natural things for such a being to eat are those foods that can be gathered and harvested—the fruits, vegetables and nuts of the earth.

Man’s hands set him apart from the other animals in his food-gathering capabilities. Man appropriates his food by picking fruits from trees or by planting vegetables. It is the hands of man that are used to obtain his food, and the most natural things for such a being to eat are those foods that can be gathered and harvested—the fruits, vegetables and nuts of the earth.

20.3.2 The Mastication of Food

=== The Mastication of Food ===

 

Man’s teeth are not curved or sharpened like those of the wolf or tiger, nor are they wide and flat like those of the grass-and-grain-eating animals. Instead, they are shaped most similar to the fruit-eating monkey’s.

Man’s teeth are not curved or sharpened like those of the wolf or tiger, nor are they wide and flat like those of the grass-and-grain-eating animals. Instead, they are shaped most similar to the fruit-eating monkey’s.

Man’s mouth is actually best suited for eating succulent vegetables and fruits.

Man’s mouth is actually best suited for eating succulent vegetables and fruits.

20.3.3 The Stomach

=== The Stomach ===

 

If a dog swallows a bone and it proceeds to its stomach, it will be completely dis- solved by the dog’s strong gastric juices. Carnivores may safely gulp hunks of meat whole because of the high acidity of the juices in their stomachs.

If a dog swallows a bone and it proceeds to its stomach, it will be completely dis- solved by the dog’s strong gastric juices. Carnivores may safely gulp hunks of meat whole because of the high acidity of the juices in their stomachs.

Humans have choked to death on similar chunks of meat. It is interesting to note that almost all of the fatal chokings on food have involved pieces of meat (vegetarians, be- ware: peanut butter is a close second on fatal food chokings).

Humans have choked to death on similar chunks of meat. It is interesting to note that almost all of the fatal choking on foods have involved pieces of meat (vegetarians, be- ware: peanut butter is a close second).

Unlike the grass-and-grain-eaters (such as cattle), man’s stomach cannot process large amounts of cellulose. He cannot regurgitate and re-chew his food as does the cow, for example.

Unlike the grass-and-grain-eaters (such as cattle), man’s stomach cannot process large amounts of cellulose. He cannot regurgitate and re-chew his food as does the cow, for example.

Nor can man’s stomach digest a mixture of all different types of food. Each food re- quires its own special set of digestive conditions in the stomach. Notice too that little or no starch digestion occurs in the stomach, and that fat digestion is a lengthy process that is only successful for small amounts of unheated fats.

Nor can man’s stomach digest a mixture of all different types of food. Each food re- quires its own special set of digestive conditions in the stomach. Notice too that little or no starch digestion occurs in the stomach, and that fat digestion is a lengthy process that is only successful for small amounts of unheated fats.

Obviously, anything in the world can be put into the stomach, and probably has. However, the physiology of the stomach is such that only foods in compatible combina- tions can be effectively digested.

Obviously, anything in the world can be put into the stomach, and probably has. However, the physiology of the stomach is such that only foods in compatible combinations can be effectively digested.

 

The length of man’s intestines is much longer than that. of the carnivore’s. This is be- cause meat tends to putrefy rather quickly in the intestines and must be expelled quickly. Man’s lengthy intestinal tract cannot handle low-fiber foods such as meat quickly. Con- sequently, such foods decrease the motility of the intestines and fermentation results, along with eventual constipation.

The length of man’s intestines is much longer than that. of the carnivore’s. This is be- cause meat tends to putrefy rather quickly in the intestines and must be expelled quickly. Man’s lengthy intestinal tract cannot handle low-fiber foods such as meat quickly. Con- sequently, such foods decrease the motility of the intestines and fermentation results, along with eventual constipation.

Constipation also disappears on a high-fiber diet. Fruit-and-vegetable-eating animals maintain excellent tonality of the intestines and usually experience a natural bowel movement after each feeding.

Constipation also disappears on a high-fiber diet. Fruit-and-vegetable-eating animals maintain excellent tonality of the intestines and usually experience a natural bowel movement after each feeding.

20.3.5 The Optimum Diet

=== The Optimum Diet ===

 

Let’s review the physiology of digestion so that we may determine the optimum human diet. First, it is obvious that man is built to be a gardener and harvester of fruits, vegetables and nuts. He does not possess the physical apparatus that the carnivorous animals have. Second, the teeth, saliva and digestive enzymes of man point to a diet consisting mainly of fruits and non-starchy, vegetables.

Let’s review the physiology of digestion so that we may determine the optimum hu- man diet. First, it is obvious that man is built to be a gardener and harvester of fruits, vegetables and nuts. He does not possess the physical apparatus that the carnivorous an- imals have. Second, the teeth, saliva and digestive enzymes of man point to a diet con- sisting mainly of fruits and non-starchy, vegetables.

Third, the length of the small intestine is too long to handle putrefying meat and is too short for grasses and grains. Humans should eat a high fiber, high-moisture diet to insure health of the small and large intestines.

Third, the length of the small intestine is too long to handle putrefying meat and is too short for grasses and grains. Humans should eat a high fiber, high-moisture diet to insure health of the small and large intestines.

# Leafy greens and sprouts;

# Leafy greens and sprouts;

# Non-starchy vegetables; and

# Non-starchy vegetables; and

# Nuts and seeds.  The following foods, while not optimum, can be handled by man’s digestive physi- ology in small amounts when properly combined:

# Nuts and seeds.  The following foods, while not optimum, can be handled by man’s digestive physiology in small amounts when properly combined:

# Starchy vegetables;

# Starchy vegetables;

# Salt, herbs, spices, etc.;

# Salt, herbs, spices, etc.;

# All processed, preserved and artificial foods; and

# All processed, preserved and artificial foods; and

# Cooked foods. The person desiring optimum health should eat exclusively from the first list of foods. These foods are most compatible with human physiology. Within this category, foods should be eaten in moderate amounts and in proper combinations.  The ultimate diet that is most conducive to human physiology and that promotes the highest level of health is the mono-fruit diet; that is, the eating of a single variety of fruit for each meal. 20.4. Questions & Answers I have just started the diet of fresh fruits and vegetables recommended in this les- son, but I’m experiencing diarrhea. What’s wrong? Nothing, actually. It is perfectly natural to have alternating periods of diarrhea and constipation when you are first changing your diet. Your entire intestinal tract is being swept clean by a high-natural fiber diet and its tone is improving to the point where it can do some much-needed “housecleaning.” The diarrhea you are experi- encing is probably occurring due to the elimination of very old fecal deposits along the colon walls. Some people, however, have periods of diarrhea because their in- testines are very sluggish due to years of abuse. They are not ready for a natural diet high in fiber and roughage. If you feel that this is similar to your case, try eating foods such as bananas, avocadoes, melons, etc. that are low in roughage. Eventual- ly, your intestines will be toned-up enough so that you experience a normal bowel movement after each meal.  I don’t really understand this business about putting only one food at a time in my stomach. Seems pretty boring!

# Cooked foods.

The person desiring optimum health should eat exclusively from the first list of foods. These foods are most compatible with human physiology. Within this category, foods should be eaten in moderate amounts and in proper combinations.  The ultimate diet that is most conducive to human physiology and that promotes the highest level of health is the mono-fruit diet; that is, the eating of a single variety of fruit for each meal.

 

== Questions & Answers ==

'''I have just started the diet of fresh fruits and vegetables recommended in this les- son, but I’m experiencing diarrhea. What’s wrong?'''

 

Nothing, actually. It is perfectly natural to have alternating periods of diarrhea and constipation when you are first changing your diet. Your entire intestinal tract is being swept clean by a high-natural fiber diet and its tone is improving to the point where it can do some much-needed “housecleaning.” The diarrhea you are experi- encing is probably occurring due to the elimination of very old fecal deposits along the colon walls. Some people, however, have periods of diarrhea because their in- testines are very sluggish due to years of abuse. They are not ready for a natural diet high in fiber and roughage. If you feel that this is similar to your case, try eating foods such as bananas, avocadoes, melons, etc. that are low in roughage. Eventual- ly, your intestines will be toned-up enough so that you experience a normal bowel movement after each meal.  I don’t really understand this business about putting only one food at a time in my stomach. Seems pretty boring!

Of course, meals should be enjoyable and satisfying. While the mono-diet is the ideal diet, it may be difficult for the person used to the average mixed diet of meat, potatoes and gravy to suddenly eat only grapes or bananas for lunch. If this is the case, continue eating your usual foods, but make sure that they are combined for better digestion. In other words, instead of having mashed potatoes and bread (two heavy starches), try a baked potato and salad for ease of digestion. Gradually, as the diet improves, you will be attracted toward simpler eating without feeling like you are making a “sacrifice.”

Of course, meals should be enjoyable and satisfying. While the mono-diet is the ideal diet, it may be difficult for the person used to the average mixed diet of meat, potatoes and gravy to suddenly eat only grapes or bananas for lunch. If this is the case, continue eating your usual foods, but make sure that they are combined for better digestion. In other words, instead of having mashed potatoes and bread (two heavy starches), try a baked potato and salad for ease of digestion. Gradually, as the diet improves, you will be attracted toward simpler eating without feeling like you are making a “sacrifice.”

It makes sense that our anatomy is most like that of the fruit-eating animals. But, it seems like man can adapt to anything. Whatever he wants to eat, he can get away with.

It makes sense that our anatomy is most like that of the fruit-eating animals. But, it seems like man can adapt to anything. Whatever he wants to eat, he can get away with.

If you are satisfied with the low-level of health “enjoyed” by modern man, then it is difficult to make a complete diet change. Consider this, however: very few in- dividuals have experienced the highest state of well-being that accompanies radiant health. People transgress natural dietary laws almost from birth. Consequently, if you think good health is merely the absence, of painful symptoms, you are missing the point entirely. Optimum health produces such marked improvements in physi- cal, mental and emotional health that it becomes a joy to live according to the laws of nature. True, you can eat anything you want—that is man’s free choice. How- ever, you can only achieve perfect health by living in accordance with the innate dictates of your own physiology.

If you are satisfied with the low-level of health “enjoyed” by modern man, then it is difficult to make a complete diet change. Consider this, however: very few individuals have experienced the highest state of well-being that accompanies radiant health. People transgress natural dietary laws almost from birth. Consequently, if you think good health is merely the absence, of painful symptoms, you are missing the point entirely. Optimum health produces such marked improvements in physical, mental and emotional health that it becomes a joy to live according to the laws of nature. True, you can eat anything you want—that is man’s free choice. How- ever, you can only achieve perfect health by living in accordance with the innate dictates of your own physiology.