THE CHEMISTRY OF THE BODY
It is to the science of chemistry that we owe our knowledge of the composition of the various foodstuffs from which dietaries are selected, as well as of the several parts of the human body which relies for its sustenance on those dietaries. But the adjustment of dietaries to the work they have to do is a more complex problem than those we have hitherto considered. We learn from the science of physiology that the human body is a laboratory in which certain juices are secreted for the digestion of foods, and that in this laboratory 117 foods must be reduced to the consistency necessary for their passage through animal membranes; for it is by passage through membranes that the nutritive parts of food find their way into the general circulation of the blood which carries them to all parts of the system. Very few foodstuffs are available for use in their natural state, and the majority of them are prepared for consumption in the first place by more or less elaborate processes included in the art of cookery. When thus prepared they should be in a fit state to undergo in the body the physical changes comprised in mastication, and the chemical changes associated with the process of digestion.
It might be surmised by the thoughtful parent that as the child’s body lacks some of the external features of the adult body, such as hair and teeth, so there might, and probably would, be corresponding lapses in the internal economy, and that therefore the food prepared for the adult would be, even in the smallest quantity, unsuited to the child. Physiologists tell us that this is so, and in particular that the secretions which in adult life are called saliva and pancreatic juice and which have the function of preparing starch for digestion, are at this time scanty in amount and deficient in chemical action. But these secretions are essential for the digestion of starchy foods, and chemists tell us that starch abounds in the vegetable kingdom from which most of the food of children is derived. It is therefore a matter of some importance that every person in charge of 118 an infant should have that amount of knowledge of chemical reactions which is requisite to enable them to detect whether a food does or does not contain starch. A child fed entirely on starchy foods suffers from malnutrition of so serious a character that death may, and often does, ensue. Even if other suitable food, such as modified milk, be given, the internal economy of the child will be seriously disturbed.
The names by which patent foods are advertised are very often misleading to unscientific persons, and invalids have suffered much from the mistaken idea that jellies and meat extracts are foods. Meat extracts have their use, but any invalid fed on extract of beef only would die sooner than one left with no food at all. The reason for this can be learned from the knowledge of the constituents of beef extracts and the part they play in the human organism.