What we eat and how much we eat must be carefully planned, for our body temple is really made of what we eat. If you were erecting a beautiful mansion you would not think of allowing cheap, trashy, and inferior building materials to enter into the construction of your home. Neither should you permit unfit and inferior materials to become a part of the daily dietary of your little boy or girl, thus to become a part of their bodily structure.
ASSIMILATION OF FOOD
Following the process of digestion in the stomach and intestine, the nutritive food elements are absorbed through the wall of the bowel by the wonderfully adapted little villus, and distributed by various routes to the uttermost parts of the body. The sugars (all starches are changed into sugar) are carried in the portal blood stream to the liver, where they are actually stored away in the form of glycogen which, in a most intelligent manner, is dealt out to the body from hour to hour as it is needed for fuel. If all the sugar, after a hearty meal, were poured into the circulation at once, the blood stream would be overwhelmed and the kidneys would be forced to excrete it in the urine. This unnecessary waste is avoided by the liver's storing sugar after each meal and dealing it out to the body as required.
Likewise, the proteins also pass through the liver on their way to the body. Just what action the liver exerts upon proteins is not wholly known at the present writing. The digested fats are absorbed at once by the lacteals, the beginning of the intestinal lymphatic system, by which they are carried to the large veins at the root of the neck and there emptied into the blood stream. We have now traced our various food elements through the processes of digestion and absorption in the alimentary tract, some going through the liver, and others through the lymphatic system, until they circulate in the blood stream itself.
It is from these food substances, circulating in the blood stream, that the various cells of the body must assimilate into themselves such portions as they require for purposes of heat and energy and for the repair of their cell substance. This specialized work of cell assimilation converts the dissolved watery food in the blood into solid tissues, exactly reversing the process of digestion.
With a most profound intelligence, each of these body cells and tissues, bone and nerve fiber, muscle and organ, selects from the blood stream just its supply or portion of the food elements requisite to its upbuilding and maintenance. The mysteries of assimilation are effected by means of chemical substances called "enzymes," similar to those found in the digestive organs, but acting in an entirely different manner, in that they build up solids out of liquids instead of converting solids into liquids.
ELIMINATION OF BODY WASTES
Metabolism consists of a twofold rôle—an upbuilding and a tearing down process. After the food is all digested, absorbed, and assimilated, having become a part of the bodily organ, bone, muscle, and nerve fiber, then begins the work of tearing it down—of liberating its heat and energy—to be followed by its elimination from the body through the sweat glands, uriniferous tubules of the kidneys, etc. The carbohydrates (starches and sugars), together with the fats, are completely burned up in the body and are then eliminated in the form of water (thrown off through the sweat) and carbonic acid gas given up by the lungs.
The proteins, or nitrogenous foods, are not so completely burned up in the body. The ashes which result from their combustion are not simple substances like the water and CO2 of the carbohydrates. This protein ash is represented by a number of complicated substances, some of which are solid (protein clinkers), which accumulate in the body and help to bring about many diseases, such as gout, headache, fatigue, biliousness, etc.
These protein ashes and clinkers are further acted upon—split up and sifted—by the liver, and are finally eliminated by the kidneys in the form of urea, uric acid, etc. The body being unable to store up protein, is often greatly embarrassed when one eats more of this substance than is daily required to replenish the waste of the body, for it must all be immediately split up in the system, and the over-abundant and irritating ashes must be carried off by the eliminating organs. Now, the overeating of sugars, starches, or fats, is not such a serious matter, as they may be stored in the liver and subsequently used; and even if they are eaten in excess of what the liver can care for they accumulate as fat or add extra fuel to the fires of the body, their ashes being carried off in the form of such harmless substances as water and carbon dioxide (CO2); but the overeating of protein substances is always a strain on the body and should be avoided.