Edward Smith

“ Thus water and minerals are found in both flesh and vegetables, while one or both of the component parts of the air, viz., oxygen and nitrogen, are distributed through every kind of food. Hence, not only may we add food to food to supply the wants of the body, but we may within certain limits substitute one for another as our appetites or wants demand. The necessity for this in the economy of Nature is evident, for, although a good Providence has given to man an almost infinite number of foods, all are not found everywhere, neither can any man obtain all foods found around him. ”

“ In reference to age, there can be no doubt that all vital processes, including the action of foods, are greater and more rapid in early, and less and slower in later, than in mature life, and in both the former a more frequent administration of food is necessary. In early life, more-over, there is the important function of growth, which demands a large and more frequent supply of food, not only for daily wants, but to promote a due increase in the bulk of the structures of the body. ”

“ So great an array of mysterious substances might well prevent us from feeding ourselves or others if the selection of food depended solely upon our knowledge and judgment; but it is not so, for, independently of the aid derived from our appetites, there is the great advantage of having foods which contain a proportion of nearly all these elements; and combinations of foods have been effected by experience which protect even the most ignorant from evil consequences. ”

“ But, in completing the circle, the vegetable receives from the animal the air which was thrown out in respiration, and lives and grows upon it, and at length the animal itself, in whole or in part, and the refuse which it daily throws off, become the food of the vegetable. Even the very bones of an animal are by the aid of Nature or man made to increase the growth of vegetables, and really to enter into their structure; and, being again eaten, animals may be said to eat their own bones and live on their own flesh. ”

“ Hence our appetites and the bountiful provision made for us extend our choice to both the vegetable and animal kingdoms, and it is possible to find vegetable foods on which man could live as long as upon animal food alone. Bread is in vegetable foods that which flesh is in animal foods, and each within itself contains nearly all the elements required for nutrition. ”

“ Food is required by the body for two chief purposes, viz., to generate heat and to produce and maintain the structures under the influence of life and exertion. The importance of the latter is the more apparent, since wasting of the body is familiarly associated with decay of life; but the former is so much the more urgent, that, whereas the body may waste for a lengthened period and yet live, it rapidly dies when the source of heat is removed or even greatly lessened. ”

“ Seeing, moreover, that the source of flesh in animals which are used as food is vegetables, it follows that vegetables should have the same elements as flesh, and it is a fact of great interest that in vegetables we have foods closely analogous to the flesh of animals. Thus, in addition to water and salts, common to both, there is vegetable jelly, vegetable albumen, vegetable fibrine, and vegetable caseine, all having a composition almost identical with animal albumen, gelatine, chondrine, and caseine. ”

“ There is a power inherent in the body which accepts or rejects food as to amount, as well as to quality, and which might at length act through the appetite, and refuse the kind supplied. Moreover, the wants of the body vary from many other well-known influences, and cause an increase or decrease in the vital actions which proceeds pari passu with the consumption of the transformed or stored-up food in a degree proportionate to the cause, but such effects are often more rapid and transitory than that of food. ”

“ As a general definition, it may be stated that a food is a substance which, when introduced into the body, supplies material which renews some structure or maintains some vital process; and it is distinguished from a medicine in that the latter modifies some vital action, but does not supply the material which sustains such action. ”

“ Thus flesh, or the muscular tissue of animals, contains precisely the elements which are required in our flesh-formers, and, only limited by quantity, our heat-generators also; and life may be maintained for very lengthened periods upon that food and water when eaten in large quantities. ”

“ Neither is it essential that every food should be decomposed or broken up, and its elements caused to enter into new combinations when forming or maintaining the structures of the body, since there are some which in their nature are identical with parts of the body, and, being introduced, may be incorporated with little or no change. ”

“ Further, there seems to be an indissoluble bond existing between all the sources of food. There are the same classes of elements in flesh as in flour, and the same in animals as in vegetables. The vegetable draws water and minerals from the soil, while it absorbs and incorporates the air in its own growth, and is then eaten to sustain the life of animals, so that animals gain the substances which the vegetable first acquired. ”

“ Thus it is possible that the amount of vital change proceeding in the body may be ten times greater in one state than in another, and it follows that a proportionate quantity of food will be required to sustain it. ”

“ But there are foods which are more valuable to the body than others, in that they supply a greater number of the substances which it requires, and such are known as compound foods, while others, which supply but one element, or which are incorporated without change, may be termed simple foods. ”

“ It may thus be shown that the division of foods into the two great classes of flesh-formers and heat-generators is not to be taken too incisively, for while a food is renewing flesh it also produces heat, and while the heat-generating food is acting it may also produce a part of flesh in the form of fat ”

“ As familiar illustrations of the production of heat from chemical change, we may mention that, when cold oil of vitriol and cold water are added together, the mixture becomes so hot that the hand cannot bear it, and the heating of hay-stacks, and also of barley in the process of malting, is well known. ”

“ There are also effects produced by foods apart from or in addition to those of nutrition, which are not common to all; so that some foods more than others influence the action of the heart, lungs, skin, brain, bowels, or other vital organ, while others have antagonistic qualities, so that one may destroy certain effects of another. ”

“ Other foods are more valuable because they are more readily changed into the substance of the body, or act more readily and quickly in sustaining vital actions, and these may be called easily-digested or easily-assimilated foods. ”

“ This increase, followed by decrease, being due to the action of food, proves that the influence is temporary, and that after a sufficient interval another supply of food is required. At the same time it must be allowed that the body is not entirely a passive agent subject to the controlling action of food, for no supply could prevent the vital actions subsiding at night, or make them equal both by night and day. ”

“ It is there illustrated that, during the repose of the night, the amount of vital action, as shown by the respiration and pulsation, is low and tolerably uniform, while under the influence of food it is high, and varies during the day extremely, but the general course is such that a large increase takes place after a meal, and a considerable decrease before the following meal. ”

“ Hence it is requisite that the body should be provided with salts of potash, soda, lime, magnesia, sulphur, iron, and manganese, as well as sulphuric, hydrochloric, phosphoric, and fluoric acids and water; also nearly all the fat which it consumes daily, and probably all the nitrogenous substances which it requires, and which are closely allied in composition, as albumen, fibrine, gelatine, and chondrine. It can produce sugar rapidly and largely, and fat slowly and sparely, from other substances ”