Life is a perpetual function; it has for its seat the organs which, working and modifying themselves incessantly, have a constant tendency to revert to their primitive type Thence a continual current of exchanges, the upkeep of which is borne by alimentation. According to its nature, it preserves in a normal state the composition and the texture of the organs, or rather transforms slowly then: substance and, with it the functional acts.

Nothing therefore is of greater importance than to know how to feed oneself properly, nothing is, however, more difficult or more misunderstood, and directly it is a question affecting mankind, we have to take note of tradition and sentiment with regard to one of the main conditions upon which closely depends individual health, family prosperity and the improvement of constitutions.

It is well known how to feed an ox, a cow, a horse or a sheep, so as to make them produce the maximum of meat, of milk, of work or of wool, one knows less well how to feed a manAlimentation has vaned with epochs, peoples and prevailing ideas , it varies mucli at the present day, and this grave and complex problem of the daily repair of the instruments of life, without a superfluous capital or deficit, is still determined most often empirically or according to preconceived notions.

Some, believing that they see the principal source of physical vigour and voluntary energy in flesh food, wish to have it in plenty, others protest that we already consume too much meat, that it charges the liver and blood – with poisons and waste products and that it ought, on the contrary, to be much reduced. Others extol vegetarianism and say that it suffices for all our needs and renders us less susceptible to disease.

Many medical men today forbid alcoholic liquors, such as wine and beer, which they declare are at least useless, if not poisonous, others believe them to be stimulating and even precious nourishment One prescribes salt and spiced dishes, another forbids them Yesterday, we were advised to drink as little as possible while eating , today, it is necessary to purify the blood by an abundance of watery drinks to carry off all poisons and residues.

Nevertheless alimentation goes on if irrationally, it leaves every day a deficit or else, on the contrary, a vexatious excess of fat, flesh, water or mineral salts, and the effects of this careless diet accumulating in the midst of the gradually modified nutritive plasmas and the organs undergo a slow degeneration, health is enfeebled, the constitution becomes more and more affected, the tissues worn out and disease is established.

It is of the utmost importance therefore that man should learn how to feed himself rationally and to preserve his youth and his strength while there is yet time. It is also necessary that the physician should know how to prescribe for him the most efficacious diet, if he falls ill there are simple rules which respond to these fundamental needs which I believe can be found in dietetics.

These fundamental rules are divided into three parts. The first would include the general principles of normal diet for a healthy man. The second would explain the nature and application of each of the alimentary substances. The third would study the variation of diet according to individuals, races, climates and ages in health and in sickness.

The laws of alimentary dietetics have a triple origin tradition when it has withstood time and theory, physiological knowledge of the normal function of the organs, chemical statistics which connect the composition and daily expenditure of the organs with the composition and the balance-sheet of the foodstuffs. These three classes of considerations should support and explain each other, and alone are valuable in establishing the rules of good alimentary dietetics, those which flow simultaneously from these three sources of our knowledge and satisfy them.

A long empiricism has introduced little by little bad habits into our customs relating to alimentation. It appears to me that the various diseases, which one is accustomed to attribute vaguely to delicate temperaments, to faulty constitutions and to idiosyijcrasies, are most often derived from defective methods of nourishment, individual or hereditary.

Arthritis, gout, megrim or neuralgic conditions, neurasthenia, dyspepsia, gastralgia, rickets, arteriosclerosis and many affections of the skin can be attributed directly or indirectly to exaggerated or indiscreet habits of diet. Physical and intellectual deterioiation which alcohol begets, and in an indirect way many affections of the heart,liver and kidneys, indeed some of the forms of diabetes itself, may be attributed directly or indirectly to exaggerated or indiscreet habits of diet and can be modified or made to disappear with them.

It is useful then that the numerous and delicate problems connected with the study of diet, in health or in sickness, should be examined by a biologist and a chemist, by the clear and penetrating light which our modern chemical knowledge throws on these important questions. More can be found out about this in the subject of dietetics.

Food is the matter that is taken into the body to supply nourishment or to replace tissue-waste. Every physical act consumes a part of the force that has been derived from food. The maintenance of the body-heat consumes another part, and in growing individuals a certain amount is utilized in building up the new tissues.

Food as it is taken into the body differs very much in composition from the material that can be utilized in cell-growth and in replacing the tissue-waste. The function of digestion is so to alter the food that it may be absorbed by the blood, and prepare it for assimilation and utilization by the various tissues. The food of mankind is most varied in nature, differing with the seasons, and with climates, races and countries.

The study of foods is a most complex one, and until recently few scientific investigations along this line had been made. Fortunately, however, experiments are now being carried on the world over, and it is to be hoped that the subject of diet in health and in disease will soon be lifted out of the vale of empiricism where it has so long rested.

Water enters into the composition of every tissue in the body and forms more than 60 per cent, of the entire body weight of a full-grown man. As it is not burned up in the metabolic processes, it does not furnish any energy.

The earthy salts, which form about 6 per cent, of the body weight of an adult man, furnish little if any energy. They are most abundant in the bones and teeth, but they also enter into the composition of other tissues and fluids of the body. The principal salts of the body are calcium phosphate and the various compounds of potassium, sodium, magnesium, and iron. The mineral salts are very necessary to life and health.

Proteins are substances which contain nitrogen, are essential to life, and are regarded as combinations of the various amino-acids. In addition to carbon, hydrogen, oxygen, and nitrogen protein generally contains sulphur and some of them phosphorus, iron, copper, iodine, manganese and zinc.

The proteins are variously classified and two elassfications, based on the solubility, have been suggested, one by the English Society of Physiologists and one by the American Society of Biochemists.

Proteins are essential to life and the body is constantly metabolizing it, whether any is being taken in or not. In ordinary life the body is in protein (or nitrogen) equilibrium and as much protein as is ingested is metabolized. It is difficult to get a positive nitrogen balance, except after prolonged fasting or after recovery from wasting diseases or during the period of body growth.

A negative nitrogen balance is seen in starvation where more is used up than is taken in and in all wasting diseases, such as tuberculosis, in fevers, and hyperthyroidism. In pathological states such as nephritis there may be retention of nitrogen compounds in the body due to the failure of the kidney to excrete them, and if the amount exceeds a certain amount a condition of poisoning and uremia is brought about.

Some food proteins are better suited for human food than others, because when broken up into their elementary parts or amino-acids more of these can be utilized in forming the various body tissues than those derived from other foods. For this reason the proteins of milk, meat, eggs and fish are most valuable, those of rice and potatoes next in value, while those of wheat, maize and beans are distinctly inferior.