1. Introduction
It has often been said: "You are what you eat." More appropriately, this should probably be: "You are what you digest and assimilate."
Man eats everything. He considers himself an omnivore of the first order. Roots, nuts, tubers, seeds, eggs, blood, milk, fish, fowl, and fruit have all appeared on man's plate. One culture eats worms and gnats with relish. Another culture considers decaying animals a delicacy. Man has practiced cannibalism both in the past and in the present.
And so man brags: "I can eat anything. I have an iron stomach."
It is true that man's physiology allows him to eat almost anything that does not immediately kill him. Sometimes even great quantities may be consumed, as witnessed by the champion crayfish eater of Louisiana who ate 63 pounds of crayfish tails at one sitting. It is a mistake to assume, however, that the body can digest and assimilate everything that passes between our teeth, or that foods doing no immediate harm will not eventually cause problems.
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.
1.1 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."
No one understands these processes completely. The transformation of an apple, for example, into the cells that make up the brain, blood and bone is an event that defies scientific duplication. The changing of food into the person that is you could be considered a miracle—yet it is a miracle that happens repeatedly throughout every day.
We can follow food through the body as it undergoes processing by the digestive organs. We can give names to the various enzyme interactions and to the catalysts that accompany food absorption. We cannot, however, tell you how the life force present in a fruit becomes part of the life force that propels your body or awakens your consciousness. These are the limitations of the science of nutritional physiology, and we must keep our discussion within the scope of these boundaries.
From a purely physiological point of view, nutrition can be described by the mechanical and chemical actions of the body upon the food ingested. Notice that the body is active and food is passive; the body acts upon food—food does not act upon the body.
As Dr. Herbert M. Shelton states: "Food is inert substance and, therefore, has no power to make living organisms. It cannot act, but is acted upon. The living organism uses what it can of the food consumed and rejects the rest. A particular food may be good, but to feed more of it than can be utilized...is worse than useless."
The idea that foods have in themselves no power to act upon the body distinguishes Life Science and Natural Hygiene from other traditional schools of nutrition. Many nutritionists still believe in "food therapy"—that is, that certain foods can perform specific actions upon the body to effect a cure or treatment. Life Science decrees that there are no "cures," whether they be in the form of medicines, herbs, foods or juices; instead, the body is a self-healing mechanism. Hopefully, by studying the physiology of nutrition, you will be able to see the fallacy of regarding foods as active healing agents.
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.