If the processes of digestion seem complex and but little understood the processes of nutrition are much more so. While nutrition is claimed to be purely chemical, it is acknowledged, by even the most materialistic, to be different in many ways from the other chemical processes known to us. This is particularly true of the final stages of the process by which the pabulum is transformed into living tissue. By this final act dead matter is raised to the plane of living matter.

Even Prof. Chittenden was forced to acknowledge that this "involves a chemical alteration or change akin to that of bringing the dead to life"; while Dr. Charlton Bastian, F.R.S., London, argued that these facts of nutrition, particularly those of the plant, in which inorganic matter is converted into the organic substances of the plant, prove to us the possibility of the creation of life from non-living. All of which shows, that, while the digestion of food materials and their conversion into living tissues is considered to be purely chemical, these are far different from any chemical actions and reactions known to the laboratory, even though the chemist may be able to discover no difference. It cannot be disputed that if the substances are the same and the processes and changes are identical the products would be, to say the least, very similar. But no chemist can even imitate the work done by plant and animal nutrition. The great mystery of nutrition is still unexplained. We can no more explain today how food material is changed into living human flesh and blood than could the lowest savage of a thousand years ago.

It is certain, however that many of the changes the food undergoes after being absorbed are due to the action of enzymes. For example there is autolytic acids, found in the tissues generally, which split the amino-acids, into simpler compounds. Then there are guanase found in the thymus, adrenals and pancreas, which changes guanin to zanthin; adenase found in the pancreas, liver, lungs, muscles, etc., which causes oxidation, as of hypozanthin to xanthin, and of xanthin to uric acid. No effort will be made at this place to take these matters up in detail. The reader who may be interested in pursuing these still further is referred to any of the standard works on nutrition. We must devote our attention to the use of foods.

Let us begin with the proteins, since these have been the subject of more discussion than any other part of our food, and are considered, by "orthodox" scientists, to be the most important of all elements of our food. All this came about as a result of the mistakes of the early physiological chemists, particularly Liebig and Vogt of Germany. These found that muscle is almost pure protein and water and Liebig thought we should eat muscle to make muscle. Of course, the cow eats grass not muscle, out of which she makes the muscle Liebig would have us eat, but this simple fact was overlooked.

Voight followed Liebig with a series of experiments on dogs. This was about 1860. With these he thought he had succeeded in proving the great physiological importance of protein. It was assumed that muscular activity is due to the oxidation of the cells themselves. It was a case of mistaking the "machine" for the "fuel;" yet, on the basis of this assumption Voight, with the aid of his dogs, estimated that the average man requires about 118 grams of protein daily. He seems later to have reduced this standard by nearly one half, but no one took the reduction seriously.

The Voight standard is now known to be much too high. Protein leaves the body through the kidneys in the form of urea. In fact, the composition of the urine depends more upon the protein (nitrogen) intake than upon anything else. By measuring the excretions and comparing these with the food consumed, it is possible to tell whether less protein or more protein is being lost than is being consumed. Examinations of the urine under almost all conceivable conditions of life and activity, have shown that in the healthy adult the nitrogen intake and output is balanced, providing, of course, the intake is not less than the actual needs of the body.

No matter how much nitrogen one consumes above the body's requirements, the organism always responds in the same way. That is, it sets aside for excretion, all surplus nitrogen. So unless the nitrogen intake is less than the body's requirements, the balance is usually struck between income and outgo. Exceptions to this are during growth, following a protracted fast, convalescence after wasting illness, and pregnancy and lactation, during which periods the body excretes less nitrogen than is consumed; and during some diseases in which there is a rapid breaking down of tissue and consequently more nitrogen is excreted than is consumed.

The body does possess the ability to store protein although compared with its ability to store carbohydrates and fats, this ability is very limited. Surplus nitrogen is carried in the blood at all times.

For growth and reproduction, larger quantities of protein are, of course, requisite, and it is even more desirable in that case that the proteins should be of high biological value. In growing children and youths the protein requirements exceed that of the adult by 50% to 100%. Pregnant and nursing women require considerably more protein than adult males or adult non-pregnant and non-lactating women.

Repeated examinations of the urine have disclosed the fact that the proportions and quantities of the urinary constituents are modified by exercise or physical labor very little. This means that protein decomposition is not materially increased by physical effort and leads to the conclusion that the protein requirements of the average healthy man or woman are no greater, while engaged in manual labor, than while engaged in mental effort.

For years the "orthodox" scientific world held tenaciously to the high protein standard set by Voight. Although Hershfeld had, in 1887, by a series of tests, placed the protein standard at 47 grams, the orthodox chemists never accepted his standard and the low protein diet did not attract much attention until Horace Fletcher startled the scientists out of their lethargy some years ago. Since then, much evidence has been accumulated by the progressive members of the scientific world, showing that protein is not so valuable as formerly supposed. In fact, the evidence is strongly in favor of the statement that protein--and certainly excessive protein--is a physiological burden and destroys health.

The experiments of Hirshfeld have already been referred to. He was a young man of 24 years and performed heavy labor, weight lifting, mountain climbing, etc., on a diet containing less than half the protein that was thought to be necessary. He lost neither weight nor strength, while the "nitrogen balance" showed that he did not lose body protein. Dr. Hindhede says of his work: "It is strange, indeed, that Hirshfeld's investigations have been allowed by science to drift almost into oblivion. He was a young man (twenty-four) who could make little impression against the weight of Voight's authority."