Nutrient

“ In order that the body may do efficient work in digestion and in the distribution of the nutrient elements of the foods, and that the evaporations from the body may be re-supplied, the water in the foods, together with the beverages drunk, should consist of about seventy-five per cent liquid to twenty-five per cent nutrient elements, or about three times as much in weight as proteins, fats, and carbohydrates combined. ”

“ How important then, that this universal solvent should be pure,—that it should be free from those foreign ingredients, whether of animal, vegetable or mineral origin, which, if introduced into the system, tend to disturb the functions of the various organs, and often to occasion serious derangement and disease. But besides its important office as a menstruum, water is perhaps the most important nutrient, of all those which sustain the existence of organized bodies. ”

“ These are examples of what I may call the selective influence of the nutrient medium. The nutrient medium used in my former experiments was a solution of gelatin and mineral salts, such as is used in general bacteriological work, modified in various ways. On careful consideration, this did not appear to be a medium at all corresponding to the natural bate. The albuminoids in the process of digestion are peptonised, and dung contains only those bodies which the animal is incapable of assimilating. It is from these bodies that the necessary enzymes are produced by bacteria. ”

“ In passing, it is interesting to observe the following: the fact that in a mixed fruitarian diet the proportion of the nutrient compounds is such as to satisfy natural requirements is another proof of the suitability of the vegetable regimen to the human organism. It is a provision of Nature that those foods man's digestive organs are constructed to assimilate with facility, and man's organs of taste, smell, and perception best prefer, are those foods containing chemical compounds in proportions best suited to nourish his body. ”

“ The unique value of sugar depends upon its intelligent use and its proper combination with other foods, particularly with those rich in the nitrogenous compounds or proteids. Sugar alone is incapable of sustaining life, but combined with other foods is a valuable nutrient. ”

“ To secure a proper and complete nutrition of the body it is desirable that all these elements should be so adjusted as to provide for complete nourishment without having any one of them in great excess. It is evident that an excess of any one or more of these nutrient materials must necessarily impose on the organs of the body an additional work in securing their proper elimination. ”

“ Hence it is [Pg 217] that the value of a food is dependent not alone on its composition, but also on its digestibility. The digestible or available nutrients of a food are determined by multiplying the per cent of each nutrient which the food contains by its digestion coefficient. For example, a sample of wheat flour contains 12 per cent protein, 88 per cent of which is digestible, making 10.56 per cent of available or digestible protein (12 × 0.88-10.56) . ”

“ Relation.—The value of a food depends largely upon the relation of one group of nutrients to another. Proper nutrition can only be obtained when a sufficient amount of flesh-forming as well as of heat-producing nutrients are present, when the “nutritive ratio” is properly balanced for the particular purpose in view, be it the growth of the child, the maintenance of the body, the restoration of matter consumed by labor of body or brain, or the supply of heat to make up for cold surroundings. ”

“ Scientists have devoted much careful study and experimentation to the determination of the quantities of each of the food elements required for the daily nourishment of individuals under the varying conditions of life, and it has come to be commonly accepted that of the nitrogenous material which should constitute one sixth of the nutrients taken, about three ounces is all that can be made use of in twenty-four hours, by a healthy adult of average weight, doing a moderate amount of work. ”

“ The use of fruits, herbs, and vegetables for medicinal purposes is based upon the presence of compounds possessing well-defined medicinal properties. As a rule food plants do not contain appreciable amounts of such substances, and the use of food for medicinal effect should be by the advice of a physician. The physiological properties of some foods are due to bacterial products. See Chapter XX.
239. Individuality.—Material difference in digestive power is noticeable among individuals. Digestion experiments show that one person may digest 5 per cent more of a nutrient than another. ”

“ Each of the broad food groups has a special contribution to make toward an adequate diet.
Here are some of the reasons different food groups are emphasized in the guide and the names of some of the nutrients these foods provide.
Meat, poultry, fish, and eggs from the meat group and their alternates—dry beans, dry peas, and nuts—are valued for their protein. This is needed for the growth and repair of body tissues—muscle, organs, blood, skin, and hair. These foods also contribute iron and the B-vitamins—thiamine, riboflavin, and niacin. ”

“ Miscellaneous Compounds in Vegetables.—In addition to the general nutrients which have been discussed, many of the vegetables contain some tannin, glucosides, and essential oils; and occasionally those grown upon rich soils have appreciable amounts of nitrogen compounds, as nitrates and nitrites, which have not been built up into proteids. Vegetables have a unique value in the dietary, and while as a class they contain small amounts of nutrients, they are indispensable for promoting health and securing normal digestion of the food. ”

“ Experiments with the cooking of carrots show that if a large amount of water is used, 30 per cent or more of the nutrients, particularly of the more soluble sugar and albumin, are extracted and lost in the drain waters. ”

“ Milk also provides protein, riboflavin, vitamin A, and many other nutrients. Cheese and ice cream also supply these nutrients, but in different proportions.
The bread-cereal group, with its whole-grain and enriched bread and other cereal products, furnishes important amounts of protein, iron, several of the B-vitamins, and food energy.
Fats, oils, sugars, and sweets are not emphasized in the guide because they are common in every diet. ”

“ For convenience of comparison foods may be divided into five classes: Water, Protein, Fats, Carbohydrates, Mineral Matters.
Some scientists include air in the list, but it has been thought best in this work to speak of it separately [19] as the greatest necessity of life, but not in the sense of a direct nutrient.
An average composition of three of the principles is as follows:
It will be seen from the above that the protein compounds contain nitrogen ”

“ When seeds germinate, small amounts of carbohydrates are converted into organic acids. In general the organic acids are not to be considered as nutrients, but as food adjuncts, increasing palatability and promoting digestion. ”

“ Eggs, milk, and sugar are the most readily convertible nutrients known to the science of food chemistry. In combination they represent the highest form of the nitrogenous (proteids and the carbohydrate) compounds, therefore to increase physical efficiency one should take as much of these as possible. ”

“ The edible material is by no means a simple substance, but consists of water, and some or all of the compounds variously designated as food stuffs, proximate principles, nutritive ingredients or nutrients, which are classified as protein, fats, carbohydrates and mineral matters. ”

“ Digestibility or Availability of Food Materials.—The value of any food material for nutriment depends not merely upon the kinds and amounts of nutrients it contains, but also upon the ease and convenience with which the nutrients may be digested, and especially upon the proportion of the nutrients that will be actually digested and absorbed. ”

“ A large portion of liquid is immediately absorbed by the blood-vessels of the stomach.
Adaptation of Foods to Particular Needs and Conditions. The demands of different individuals for nutrients in the daily food vary with age, occupation, and other conditions of life, including especially the peculiar characteristics of people. No two persons are exactly alike in their expenditure of muscular and nervous energy, so no two will need the same amount or kind of nutriment to repair the waste.
A man who digs in a field day after day expends a certain amount of muscular energy. ”

“ It will be noticed that the table is divided into two parts, the first part giving the value of the total nutrients, and the second one the value of the protein nutrients. It frequently happens that we have plenty of carbohydrates and fat, but that we are lacking in protein. ”

“ Wheat contains about 11.9 per cent of protein or the flesh-forming elements; corn, 11.4 per cent; oats, 11.8 per cent; rye, 10.6 per cent; and barley 12.4 per cent. [A] It has further been demonstrated that a man or beast doing heavy work, requires a larger proportion of starch and sugar in his dietary than does one which has less work to do. Likewise, different classes of animals require different proportions of the various nutrients, not only through life but at the various periods of their lives. ”

“ I do not mean by this that the vegetable we should use shall be grass itself, or that grass should be one of the vegetables. We must, for our requirement, select vegetables that contain as much nutriment in a given bulk as our present mixed diet, but in doing so we encounter the serious difficulty of finding that the readily soluble cell-wall or main bulk of animal food—the gelatine—is replaced in the vegetable by the cellulose, or woody fiber, which is not only more difficult of solution, but is not, nitrogenous—is only a compound of carbon, oxygen, and hydrogen. ”

“ White of egg and lean meat are almost pure protein and water. Proteins are most abundant, as we should expect, in those plants which are richly supplied with nitrogen; peas and beans, and in grains and nuts. Fats, which are melted into oils at the temperature of the body, are represented by the fat in meats, bacon, pork, lard, butter, and vegetable oils.
Water.—Water is, as we have seen, a valuable part of food. It makes up a very high percentage of fresh fruits and vegetables; it is also present in milk and eggs, less abundant in meats and fish, and is lowest in dried foods and nuts. ”

“ Water must be considered as a part of our nutriment, because so much of it enters the composition of our solids as well as of our fluids; and because vegetables are now believed to draw almost the whole of their nourishment from this source. As in them the water is decomposed, as it is perspired by them in the sunshine, the oxygen gas increases the quantity and the purity of the atmosphere in their vicinity, and the hydrogen seems to be retained, and to form the nutritive juices, and consequent secretions of rosin, gum, wax, honey, oil, and other vegetable productions. ”

“ The cultivation of our crops has ultimately no other object than the production of a maximum of those substances which are adapted for assimilation and respiration, in the smallest possible space. Grain and other nutritious vegetables yield us, not only in starch, sugar, and gum, the carbon which protects our organs from the action of oxygen, and produces in the organism the heat which is essential to life, but also in the form of vegetable fibrine, albumen, and caseine, our blood, from which the other parts of our body are developed. ”

“ The chemical constitution of the human body is made up of a large variety of elements and compounds. From fifteen to twenty elements are found in it, chief among which are oxygen, hydrogen, carbon, nitrogen, calcium, phosphorus, sodium, and sulphur. The most important compounds [Pg 72] are protein, hydrocarbons, carbohydrates, organic mineral matter, and water. The food which nourishes the body is composed of the same elements and compounds.
Food serves two purposes,—it builds and repairs the body tissues, and it generates vital heat and energy, burning food as fuel. ”

“ Chemical analysis of various articles of diet shows that not only are the elements of human nutrition all present in the plant kingdom, but in more abundant quantity in many of the articles in common use, and combined in more suitable proportions, than is the case with any animal flesh.
In muscle making properties barley, southern corn, oats, wheat, beans, lentils, peas etc., outrank beef; in heat and fat producing, nuts, sweet cherries, dates, figs, prunes, barley, buckwheat, corn, oats, rice, rye, wheat, beans, lentils, peas, sweet potatoes etc., far outrank the meats ”

“ The proper adjustment of the relative quantities of the great groups of nutritive elements in the food is a matter the importance of which cannot be over-rated, for it is in fact the foundation of successful and economical feeding; and this will be readily understood if we consider what would be the result of giving to an animal a supply of food containing a large quantity of nitrogenous and a deficiency of fat-forming compounds. ”

“ The estimation of the value of the flesh-forming materials is far more difficult than that of sugar, starch, pectine compounds, and fat. The nitrogenous constituents of food must be in a highly elaborated state before they are capable of being assimilated. In seeds—in which vegetable substances attain their highest degree of development—they probably exist in the most digestible form, whilst much of the nitrogen found in the stems and leaves of succulent plants, is either in a purely mineral state, or in so low a degree of elaboration as to be unavailable for the purpose of nutrition. ”