In this chapter we will consider the dietetic values of various foods. Our estimate of the worth of various foods, or groups of foods, will take into consideration all scientific facts discussed in the last three chapters, that is, the chemical analysis, digestibility and effect upon the digestive action, and also the question of the presence or deficiency of vitamines, etc. But in this chapter we will consider the foods for their qualitative worth only. The questions of pro-portioning the food, and of the total quantity of food to be used will then be considered in the two chapters that follow.
In considering the entire list of human foods, the simplest and most natural grouping or division is that of animal versus vegetable foods. The question of vegetarianism is indeed the oldest, and’ has been the most discussed of all food problems. Modern scientists insist that man is omnivorousthat is, that he .can eat and can, if necessary, live on either vegetable or animal foods, or a combination of the two. In this respect he differs, on one hand, from such species as the cow or horse, which are obviously vegetarian; and on the other hand, from the lion or wolf, which are strictly carnivorous. Man shares this omnivorous habit with many other species. To mention familiar examples: the rat, the pig and the chicken.
Man, like other omnivorous species, has teeth and digestive organs that are intermediate between the strictly vegetarian and the strictly carnivorous species. Many students of the subject, have, however, questioned the fact that man is naturally a meat-eating animal. They hold the view that his teeth and digestive organs are adapted to a diet of fruits and nuts, which are unquestionably the chief items of food eaten by man’s nearest kin, the apes, and therefore, presumably, by man’s ape-like ancestors. These two views are not as divergent as they may at first seem, for most apes probably add to their nut and fruit diet birds’ eggs, and perhaps some insects and lizards.
All things considered, we are safe in assuming that man’s natural ‘diet was predominantly a vegetarian one, with a smaller proportion of foods of animal origin. The two chief changes in the diet of civilized man are the inclusion of meat from larger animals, and hence in larger quantities, and the use of grains or cereals. Neither of these types of foods which make up the bulk of man’s present diet were available to his ape-like ancestors. The use of weapons and of fire accounted for the addition of meat, and the development of agriculture and devices for the harvesting and milling of grain made possible the second addition. Such resources greatly increased the total foods available for man, and largely accounted for the increase of the species, and the establishment of the human animal as the ruler of the earth.
It does not follow, however, that the diet consisting chiefly of meat and grain is the most wholesome and beneficial diet that man can use. Indeed, present-day scientific knowledge indicates that such a diet is not the best, and that while it has advantages of economy, its use has only been possible because it has been supplemented by animal products, such as milk and eggs, and by a considerable variety of vegetable foods other than grains.
No one today among civilized men advocates an exclusive meat diet, except where prescribed for the treatment of consumption and other diseases. Indeed, no men have ever existed upon it, except the Eskimos, and their rather miserable existence has been possible only by the abundant use of the internal organs of animalsa diet which no civilized man would care to adopt. The meat diet may have advantages to the Eskimo not only because the fat gives him large quantities of fuel to keep him warm, but because lean meat stimulates the rate of heat production in the body during the process of its digestion.
On the other hand, many races and groups of men have existed upon an exclusively vegetarian diet. The consensus of opinion today is that the best diet for man is what is known as the lactovegetarian diet, that is, a diet consisting of foods of vegetable origin, supplemented by milk (and milk products), or milk and eggs.
Moderate quantities of meat foods may be used in the diet without materially changing its effect. And remember that lamb, veal, and pig of all kinds should especially be avoided. When you actually need meat, beef is probably the best bind to select, though mutton can sometimes bc recommended. My favorite meat is the top cut of “round” steak ground up and boiled for one or two minutes in a few spoonfuls of water or until the red color disappears. It is also palatable broiled. Chicken and fish are also desirable meats, but not as nourishing as beef.
Meat, however, is inferior to milk and eggs in most casesthere are exceptions. Both groups of food supply growth proteins of superior quality to those derived from any vegetable foods, but meat is deficient in minerals and in vitamines: A diet consisting of a goodly variety of vegetables, including an abundance of green leafy vegetables, and containing a small proportion of meat, will support life without the use of milk. This indeed is the type of diet upon which Chinese and Japanese have subsisted for centuries. Population is too congested in those countries to permit of the keeping of dairy herds; they do, however, keep poultry, and hence eat eggs. But this Oriental diet is not equal, especially from the standpoint of the nourishment of children, to the diet available in dairying countries. Recognizing this fact, the Japanese Government has made every effort to increase the dairy industry in their croweded land, and in lieu of their inability to produce sufficient milk, the Japanese import condensed milk from other countries.
Meat adds no essential food values that can not be derived more cheaply from other sources if the digestive organs are normal. As used in the conventional American diet;, meat supplies entirely too much protein, which sometimes results in overburdening the excretory organs with nitrogenous waste products. Moreover, meat contains the waste products of the animal and these substances are very similar to the waste from human cells, though with a healthy digestion this is easily eliminated in the alimentary canal.
For the further consideration of foods of vegetable origin, we can divide them in the following groups:
Grains and Grain Products Roots or Tubers Leafy Vegetables Fruits Nuts Extracted Oils Extracted or Manufactured Sugars
All of the above groups of foods are whole-some and may be included in the diet, but they are not equally complete, or of equal dietetic worth. Some of these foods, while harmless if used in moderate quantities and in proper combination with other foods, result in a seriously deficient diet if used in such proportions as to crowd out other groups.
Because of the mistakes of flour manufacturers all grains and grain products could be entirely eliminated from the human diet, and thereby decrease the danger of dietetic deficiencies and inadequate nutrition. But it is difficult to do this because grains and their products supply the great bulk of human food. Indeed it would not be possible, without revolutionary changes in our agriculture and food producing methods, to sup-port the human race without the use of grain. . Grains are the seeds of various grass plants. The bulk of the substance of all grains is starch. Together with this starch is incorporated from eight to fifteen per cent of vegetable protein. This protein we will ignore in the present discussion as it is not of a very high order of nutritive value and better protein may be derived from other sources. The starchy substance of grain may be ground up to produce flours and meals which keep well and which are the basis of our bread-making and baking arts. In addition to this starchy portion, which fills the endosperm or bulky interior of the grain, all grains have an outer coating of bran, and also a germ. The milling industry adopted the practice of removing both bran and germ. There were several reasons for this. In the first place, the bran and germ cannot be ground as fine as the starchy interior of the grain. Also, they are usually darker in color. Therefore the inclusion of the bran and germ produces a coarser, darker flour. The refined flour from which these elements of grain have been removed is whiter and finer and, incidentally, will make a lighter, airier loaf of bread. Such a flour appealed to the fastidious taste of the housewife; hence as they developed machinery with which to manufacture it, the millers vied with each other in the production of the whitest, finest flour possible. Another reason that favored the production of this super-refined flour was that the exclusion of the germ made the flour of better keeping qualities. The germ contains-a small proportion of oil, and if the flour was stale, this oil became slightly rancid, giving the flour a strong flavor.
In the manufacture of degerminated cornmeal, both the bran and the germ are removed. While rice is never ground, this same idea of a white and seemingly pure product resulted in the development of the process of polishing, in which the bran and germ are rubbed off the grain.
‘In all these cases, the removal of the bran and germ results in a serious loss in nutritive values. The interior white portion of the grain is almost entirely devoid of minerals and vitamines. These are more abundant in the bran and germ; more-over, the bran, especially in the case of wheat, is exceedingly valuable to give bulk to the diet and prevent constipation or intestinal congestion.
If white flour and similar denatured cereal products were used only in small quantities and combined with ample quantities of milk and green vegetables, it is probable that no serious harm would come from their use. But, as these cereal products, in the form of bread and other bakery goods usually compose: a large portion of the diet, a denaturing of the grain in the milling process is a very serious evil. Even though the use of the denatured product might be tolerated with the precautions above mentioned, the discarding of the bran and germ is a serious economic waste, for it must be replaced with similar nutrients from other and more expensive sources.
By all means, I heartily advise the use of whole wheat and whole wheat products, of cornmeal made from the whole grain, and of unpolished rice. These natural cereal products contain the coarser fibre substance of the bran, and the minerals and vitamines of the germ, and are unquestionably more nearly complete foods than the refined products. Used with whole milk or milk and butter, the entire grain cereals, particularly wheat, make a practically complete diet. Such a combination is one of the cheapest and most palatable diets possible and -may be safely used as the basis or bulk of any low-cost diet.
In cases where there is too much fermentation in stomach and bowels, bread of any kind is often troublesome. This is especially true where there are catarrhal conditions of nose, throat and lungs. And this reference applies more particularly to breads made of yeast or other similar ferments. Unleavened bread is not so objectionable, though a diet devoid of breads of any kind is often desirable in cases like this. Zwieback can be excepted, as its fermentative elements are destroyed in the prolonged cooking process to which it is exposed.
Roots and tubers, of which the potato is the most used, are somewhat similar to grain in composition. In either case, the bulk of the food material is starchor, in the case of beets and sweet potatoes, starch may be in part replaced by sugar. But the root vegetables are moist, and contain from seventy-five to eighty-five per cent of water. If roots are dried, they then become quite similar in composition to dry cereal products.
The natural roots contain considerably more minerals than do the refined cereals. The pro-portion of the various minerals are different in different root vegetables. Turnips, for illustration, are very rich in calcium. Taken as a group, the root vegetables are equal or superior to whole wheat as a source of minerals. Like the grains, the root vegetables are devoid of the fat-soluble vitamine which is found in butter or milk fat, in the egg yolks and in green leaves. The addition of potatoes or other root vegetables to a diet of grains and meat does not, therefore, make the diet complete.
The root vegetables should by all means be used in the diet in moderate proportions. They supply cheap and nourishing; fuel food in the form of starch and sugar combined with fibrous or cellulose matter, and a variety of mineral salts. The fact that such vegetables are marketed in a moist condition makes them palatable, and permits of their being cooked and served in a variety of pleasing and tasty ways. Moreover, the millers have not gotten in their work of refining them and removing their more valuable ingredients.
The leafy vegetables have many attributes to recommend them. On the whole, present scientific knowledge rates them as the most essential foods known, with the exception of milk and eggs. This does not mean that leafy vegetables would do as the whole diet of man. Indeed, they are so bully that a man would have difficulty in eating enough of them to sustain life. But their use to supplement other foods and prevent the deficiencies of our conventional foods cannot be too highly recommended.
The essential qualities of leafy foods are: first, the vitamines, all of which seem to be present in leaves; second, the minerals, in which leaves are very rich; and third, in the presence of cellulose, which gives bulk to the food in the same way that wheat bran does. Leaves are also richer in protein than grains or roots, and this protein is probably more available than the stored protein of dry vegetable food.
As an illustration of the mineral value of leaves, spinach contains more phosphorus, calcium and iron in proportion to its other food ingredients than any other food of which we have the analysis. Lettuce ranks as a very close second. Cabbage, in which the leaf is not quite so active, has only about half as much mineral as spinach. But all these leafy foods out-rank in their proportion of mineral ingredients any of the foods derived from grains, fruits, nuts or meat. They are equalled only by milk, cheese and eggs.
It does not, of course, follow that all leaves are suitable for human food. The leaves usually used are the tender leaves of quick-growing vegetables. The leaves of trees usually contain tannin or other substances that are either unwholesome or unpalatable. Leaves may also have too much cellulose or fibre to be palatable. For this reason we prefer the quickly grown tender leaf and have selected for garden cultivation the tender and more tasty varieties. Tea leaves are an illustration of the use of a leaf as a food which is hardly in keeping with the recommendations of leaves here given. The tea leaf is nearly as strong in tannin as the oak leaf and, like the coffee berry contains an alkaloid narcotic peculiar to the species.
The edible leaves, in their fresh condition, contain large amounts of water. Hence, they should not be valued too highly per pound, as it is only the dry weight that counts as food. However, as leaves are not to be relied upon for the fuel supply of the diet, this watery condition or low calory rating does not count heavily against them.
The high value of. leaves as food is attributed to the fact that they contain the active, growing cells of the plant. This same thing is true of buds and very tender shoots, or of seed-pods in the immature stages of development. Thus asparagus tips and string beans may, for practical purposes, be considered in the leafy vegetable group of foods. Some of these same attributes are found in the immature green corn or green pea.
There are a few vegetable, in which the portion used as food consists of a, tender stalk. For illustration: celery and rhubarb, or pie-plant. These tender stalks rank between the root vegetables and the leaves in food quality.
There are a few foods classed as vegetables commercially which botanically rank as fruits; such as melons, tomatoes, cucumbers and the egg-plant. Melons have no particular food value; they consist chiefly of sugar and water. The cucumber is about as devoid of food value as any substance eaten by man. The pulp of pumpkins and squashes ranks somewhat lower than the poorest root vegetables. The value of the pumpkin pie is in the milk and egg.
The tomato, on the other hand, is a distinctive and valuable food, being rich in minerals and in organic acids.
Fresh fruits, considered for the food substance contained, are the most expensive of all foods. This expense is due to the fact that fresh fruits contain very large quantities of water. Dried fruits are of much greater value per pound. Such foods as dates, figs, raisins and prunes, even considered from the standpoint of their caloric or fuel value, are worth nearly as much as dried cereals. In all other attributes they excel cereals. In the first place, their fuel substance is in the form of sugar, and this natural sugar, unlike that from the cane or beet, is already in the form in which it may be absorbed directly into the blood; hence, is less likely to ferment in the digestive organs. Secondly, fruits contain minerals which are absent from refined sugar. Fruits also contain a proper amount of fibre or cellulose which aids digestion. Lastly, fruits contain organic acids which, strange to say, actually pre-vent an acid condition of the blood. This seeming contradiction is due to the fact that the organic fruit acids are really acid salts formed of a combination of organic acids with basic or alkaline minerals. In the process of digestion and assimilation, the organic acids are oxidized, freeing the alkaline salts for new combinations which serve to neutralize the harmful acids developed by the physiological processes.
The vitamine content of fruits has not been fully investigated, but we know that the juice of limes or oranges is a remedy for scurvy, and we may safely assume that fruits contain the water-soluble vitamine. Fruits are probably deficient in the fat-soluble vitamine, which seems to be supplied in abundance only from milk or egg fat, or from green vegetables.
No scientific consideration of the subject can fully portray the dietetic value of fruits; for above all other foods, their value lies in the flavor or appetizing quality, and the consequent pleasure to be derived from their use. Fruits are the natural dessert and should be used as such. With the possible exception of dates, figs and raisins, fruits are not to be considered as suitable for forming any great bulk of the diet, or replacing other food groups. But these sweet fruits may be very profitably used in the place of artificial sugars, and also to cut down the quantity of cereal starch.
Nuts are botanically similar to grains or dried legumes in that they are the seeds of plants. We, therefore, assume the nut to be deficient in vitamines and minerals as are other seeds; but nuts differ markedly from grain in that the stored fuel food is predominantly in the form of fat instead of in starch. This makes the nut about twice as valuable, even as a source of fuel. A certain portion of fat is necessary in the diet as a matter of palatability.
Nuts have played a prominent part in all vegetarian menus. The high rating so given them was originally due to the fact that they are the richest in protein of any vegetable foods, with the possible exception of beans and peas. From our present knowledge we do not rate this protein so highly, both because we now realize that the body does not need so much protein, and because we now know that vegetable proteins are not as assimilable by man as protein of animal origin. Thus it would seem that our recent knowledge indicates that we formerly placed too high a value upon nuts. This much may still be said in their favor: the nut protein is free from any of the toxic waste products that may be present in flesh foods. Also the fat of nuts is exceedingly nutritious and wholesome and has a decided advantage from the standpoint of digestibility over the animal fats which are used in frying or in the making of pastry.
Nuts should be used in the diet as a food, not as a relish; that is, they should be a part of the meal and not taken in addition to the meal. Nut meats should be thoroughly masticated, as they are not digestible when swallowed in large particles.
While nuts are not essential to the diet, they are a pleasing and tasty food and may be very profitably used in moderate quantities, especially in those diets from which meats and animal fats are eliminated.
Extracted fats or oils, whether of animal or vegetable origin, have no food value whatever except as a source of fuel. In this respect, pure oil is worth about two and one-quarter times as much as sugar, or two and one-half times as much as dry cereals. No diet is palatable and presumably is not wholesome without some proportion of fat. The best source of fat in food is in the form of the emulsified fat of milk, cream or egg yolksor in a somewhat more concentrated condition in butter and cheese. In all these cases the fat contains the highly important fat-soluble vitamine which does not exist in such fats as lard, cotton-seed oil or oleomargarine.
The second preferable form of fat is that of nuts. The amount of. extracted nut fat to be used in the diet will depend upon the amounts used in the above-mentioned and preferred forms. I should say that, in a meatless diet, the use of milk, butter, eggs and nuts would supply all the fat actually needed, but that an additional amount may be used in the form of oil, either alone or combined with other ingredients, as salad dressings.
Where fat is used in all the above-mentioned forms, the additional use of fat in the frying of foods or in the concocting of rich pastries is a wasteful and harmful habit. In the first place, such additional fat is not needed and is therefore inclined to over-enrich the diet and lead to over-eating. Secondly, the combination of fat with starch and sugar, either in frying or when mixed with the ingredients, results in a product which is notoriously difficult of digestion. Thirdly, such fats are absolutely devoid of minerals, proteins and vitamines, and hence their use increases the danger of deficiency of some of these most essential elements.
All that has been said about the surplus use of fat in cooking applies to the use of fat meat. It has nothing to recommend it at all, except that of being a source of fuel energy in a most concentrated form. Its use may be excusable in the diet of the Eskimo, or other men doing severe work in rigorous climates, but for- the ordinary American, especially if he be an indoor worker, the use of fat meat or excessive fat in any form is a dietetic evil.
Many of the arguments above given against the use of fat apply to the use of ordinary commercial sugar. In the plants from which sugar is derived, it is at least combined with mineral salts, cellulose and the water-soluble vitamines. But in the refining process., all these elements are discarded and we have chemically pure sugar. We have no reason to believe that sugar in itself is any other than a wholesome food, but the trouble is that we add it to a diet of refined cereals, meats, potatoes, and refined fats, all of which are already deficient. This addition of sugar merely results in increasing the proportion of such deficiency.
If any one of the deficient foods enumerated in this chapter were the sole offender in a diet other-wise made up of natural foods, there would be little occasion for concern over its use. But when the millers rob us of the minerals and vitamines of our grains, and we then add large quantities of refined fats and sugars, the danger of food deficiency is very real. It may be possible to protect against such deficiencies by the use of milk and green vegetables, but the wiser plan would be to use also natural whole grain products, and to cut down the quantity of refined fats and sugars to the minimum amount necessary to pre-pare our food in palatable form. Even this last suggestion is merely a concession to convention, for it is entirely possible to select a diet containing, dairy products, nuts and sweet fruits from which refined fats and sugars may be eliminated altogether.