The usual term "nervousness" conveys to the mind of the average person such conditions as sleeplessness, restlessness, lack of mental and physical tranquillity, but to the trained mind of the food scientist or physician, it means mental aberration, hallucinations, morbidity, mental depression, lack of self-confidence, uncertainty, loss of memory, fear of poverty, anticipation of accident, tragedy, death, insanity, and a multitude of things that never happen. Language cannot adequately describe or convey to the mind of another person the strange impressions that sweep o'er the mind—the mental anguish caused by an ordinary case of nervous indigestion. Those only who can understand why many good men and women sometimes take their own lives, or commit some great crime, are those who have experienced the same affliction.
If we could correctly interpret the various symptoms given to the brain from the nervous system, and would heed these symptoms, the body might be kept in almost perfect health under all conditions of civilized life.
Relation of nutrition to nervousness
The lack of fresh air and exercise is always told by nervous expression, but the most important and significant message conveyed by the nerves at the brain is that concerning food and general nutrition. Instinct often leads us to fresh air and exercise, but with our food it is vastly different. We acquire a taste for certain things; the habit grows upon us, and though the nerves tell the story to our senses over and over, we heed it not because we are held behind the bars of habit by the tyranny of appetite. In this respect the tobacco fiend, the drug fiend, and the food fiend are all in the same class.
CAUSES
Nervousness usually has its origin in disorders of the functions of metabolism, assimilation and elimination. In other words, somewhere between the time the food is first taken into the system, and the time the poisonous débris of the food and the body waste is finally eliminated, there are some grievous faults of function.
Some deficiency in the activity and in the secreting power of any of the digestive organs; some defect in the assimilation of the finished pabulum; some short-coming in the process by which oxygen is carried through the system to convert the "end-products" into less toxic substances for final excretion—any or all of these causes may conspire to produce nervousness. These may again, in their turn, be due to causes that arise within the mind, inhibiting the proper functional activity of the body.
But overfeeding, or eating the wrong combinations of food, and lack of proper elimination, are probably the most frequent causes of nervousness. When we take into the system more food than the body requires, there is bound to be a certain amount of it which cannot be utilized to build tissue, or furnish heat, or supply mineral salts.
This excess food, under the influence of fermentative processes, breaks down into various poisonous products. This is especially true of the albuminous elements of the food. For these, in the heat and moisture of the small intestine, rapidly undergo a process of rotting—this is exactly what it is—and develop some of the most virulent organic poisons known to man.
They exercise a profound depression upon all the physiological functions, and cause an actual toxic degeneration of the nervous protoplasm. This, in turn, causes nerve irritability, insomnia, and many of those protean symptoms roughly grouped under the head of neurasthenia.