FOOD SCIENCE. - It is the study of man's dietary needs and, in a broader sense, also of those of animals and plants, and of the ways in which these needs can be adequately met.
I. HISTORICAL BACKGROUND
From the very appearance of man on earth the determinism of human actions had to be the reproduction and preservation of the species, the search for daily food; hence an uninterrupted succession of migrations of peoples, wars, revolutions, etc. The principal aspects of primitive civilizations were determined by the activities carried on by man to procure food: hunting, fishing, gathering wild plant foods, first; pastoralism and agriculture subsequently. Very many years were necessary, however, before his nutritional needs were scientifically defined.
The most ancient testimonies that demonstrate man's interest in the nutritive qualities of foods come to us from Egypt and Babylonia, and date back 4000 and 5000 years. Later, in 460 B.C., in Greece, Hippocrates was the first to associate the study of medicine with that of nutrition; it was only after the beginnings of the Christian era, however, with Galen, that this association bore its practical fruits.
The first reports concerning the transformations that food undergoes in the organism are owed to Fernel (1543), to van Helmont (1577) and to Sanctorius (1614); but the great progress came after the discovery of oxygen. It was Lavoisier (1777) who explained the importance of this gas for living organisms and measured the degree of combustion in human subjects, thus laying the foundations of animal calorimetry. The relations between combustions and foods could be better established later, with precise knowledge of the chemical constitution of the latter, and Beccari (1728) and Liebig (1842) with his school contributed to this. A pupil of the latter, Voit (1866-73), established that the protein requirement depends on the organized mass while the lipid and carbohydrate requirement depends on the activity of the organism. The foundations of the science of nutrition were thus laid: scientists such as Rubner, Atwater, Müller, Lusk, Chittenden, Mendel, Sherman, Mc Collum, Albertoni, Rose, etc., contributed to its further development.
II. CURRENT CONCEPTIONS
Research aims at achieving the goals of the science of nutrition: 1) on the constitution and function of foods; 2) on the energy and material transformations (metabolism) that take place in the organism depending on its various functional states.
1. The chemical and functional study of foods
It has made it possible to identify in foods and to group the following nutritive principles: a) energy principles, which supply chemical energy usable by the organism and convertible mainly into heat and work (they include carbohydrates and lipids; only secondarily proteins); b) plastic principles, which supply the material indispensable for the growth and maintenance of tissues (they are represented by proteins and their amino acids, but for the same purpose carbohydrates, lipids and mineral elements also serve, albeit in limited quantities); c) principles that keep the vital processes as a whole intact and efficient (this group includes vitamins and mineral salts). d) To these nutritive principles must be added water and oxygen, indispensable for the completion of all reactions.
2. The study of energy and material metabolism
It has made it possible to consider the alimentary reaction under two aspects which, though treated separately for convenience, must nevertheless be considered as a unity: a) energy aspect. Every vital activity requires an expenditure of energy that occurs at the expense of the chemical energy of foods, which corresponds to that released by them in an organism that utilizes them, and amounts to 4.1-9.3-4.1 calories, respectively for each gram of carbohydrates, lipids and proteins. It is this energy that during vital activity is converted into internal work, defined by the name of basal metabolism, and into external or muscular work which, added to the former, expresses the total energy metabolism. The values of this metabolism have been determined in the various functional states; they are expressed in calories and define the energy aspect of the alimentary requirement, which varies with age, sex, work, etc.
b) Qualitative aspect. Equal energy value does not, however, correspond to an equal biological value of a ration, which is conditioned by various indispensable factors and bound to the law of the minimum.
It is always necessary to introduce with foods a minimum of proteins, or rather of certain essential amino acids, for the organism, which lacks the capacity to synthesize them. To evaluate the importance of the protein aspect of nutrition, it suffices to recall the highly variable structure of proteins (which causes their high specificity), and the fact that enzymes, numerous hormones, viruses, antibodies, etc., are protein in nature. Lipids and carbohydrates are also among the factors for which a minimum cannot be exceeded, below which the metabolism is altered.
Since numerous inorganic elements are found in the organism in the form of soluble and insoluble salts, they must be introduced into it from outside.
There is scientific justification for holding that, in order to ensure the organism's mineral requirement (including that of those elements which in traces perform important functions), it is sufficient to ensure the ingestion, in adequate quantities, of four elements — calcium, phosphorus, iron and iodine — which, if deficient, alter many vital manifestations.
Vitamins are substances of the most disparate structures which, even in very small quantities, regulate the unfolding of very delicate physiological processes; many of them form part of enzymes (complex substances that catalyze the innumerable chemical transformations that take place in the organism). Not all vitamins, isolated and chemically identified, are recognized as important for human nutrition; the best known are: vit. A or axerophthol, vit. B₁ or aneurin, vit. B₂ or riboflavin, vit. PP or niacin, vit. C or ascorbic acid, the antianemic vitamin or folic acid, vit. D or antirachitic factor, vit. E or tocopherol, vit. K or antihemorrhagic factor, vit. P or permeability factor.
The human organism does not synthesize them, so they must be administered to it with foods. Through the chronic deficiency of one or more of these limiting factors, the organism is subject to special morbid forms due to nutritive deficit, designated as deficiency diseases.
It is today fully demonstrated how, and to what extent, developmental anomalies, growth defects, intellectual retardation, are connected to alimentary diets qualitatively and quantitatively insufficient. It is a diet balanced in all its constituents that allows the functioning of the organism at the maximum level of efficiency and output. The conquests in the field of the science of nutrition moreover influence the agricultural and commercial activities of every country for the purposes of production, distribution and preservation of foodstuffs, with consequences no less profound than those brought about in the field of medicine, of individual and of social hygiene.
Bibliography11 works
Antonietta Orrù