The Chemistry of Food and Nutrition by A. W. Duncan (i want to read a book .txt) 📖
- Author: A. W. Duncan
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Our reason for devoting so much space to the consideration of the quantity of proteid matter required, is that in the opinion of many eminent writers it is the crux of vegetarianism. They have stated that it is impossible to obtain sufficient from vegetable foods alone, without consuming an excessive quantity of carbo-hydrates. We will summarise the argument as given in Kirke's Physiology, as edited by Morrant Baker, a standard work, and which is repeated in Furneaux's "Animal Physiology," a book which is much used in elementary science schools: "The daily waste from the system amounts to, carbon 4,500 grains (or 300 grammes), and nitrogen, 300 grains (or 20 grammes). Now let us suppose a person to feed on bread only. In order to obtain the necessary quantity of nitrogen to repair this waste he would have to eat nearly 4¼ lbs. daily.... He would be compelled to take about double the quantity of carbon required in order to obtain the necessary weight of nitrogen.... Next, let us suppose that he feeds on lean meat only. Then, in order to obtain the necessary quantity of carbon, he must eat no less than 6½ lbs. daily.... In this case we notice a similar waste of nitrogen, the removal of which would give an undue amount of work to the organs concerned.... But it is possible to take such a mixed diet of bread and meat as will supply all the requirements of the system, and at the same time yield but little waste material." (These extracts are from Furneaux, the next is from Kirke. The figures and argument is the same in each, but we have chosen those sentences for quotation which are the briefest and most suitable; certain calculations being omitted.) "A combination of bread and meat would supply much more economically what was necessary ... so that ¾ lbs. of meat, and less than 2 lbs. of bread would supply all the needful carbon and nitrogen with but little waste. From these facts it will be plain that a mixed diet is the best and most economical food for man; and the result of experience entirely coincides with what might have been anticipated on theoretical grounds only." Professor Huxley, in his "Elementary Physiology" uses almost the same figures and argument.
The adoption of this high proteid or nitrogen figure would lead to some ridiculous conclusions. One writer states that 18 eggs would contain sufficient flesh forming substance for a day's ration, but a very much larger quantity would be required to supply enough carbon. On the other hand, Professor Church says that, no less than 70 lbs. of pears would have to be eaten per day, to supply the necessary quantity of nitrogen; although the carbon would be in excess. The curious may calculate the proper quantity of each that would make a theoretically perfect dietary. People are apt to assume that what they themselves eat, or what their class, race, or nation eat, is the proper and necessary diet; at least as far as the elementary constituents and quantities are concerned. The error is in attempting to make a vegetarian diet, however contrary to common sense and the experience of the greater part of the earth's inhabitants, agree in composition with the ordinary lavish flesh dietary of the well-to-do European. It is significant that John Bull is caricatured with a large abdomen and a coarse, ruddy, if not inflamed face, indicative of his hearty dining on flesh, coarse food and alcoholic drinks. An unhealthy short lived individual. Even if we accept a high proportion of proteid, it is possible to combine purely vegetable foods so as to give the required quantity of the various constituents, without a superfluity of the carbo-hydrates. In "Food Grains of India," Professor A.H. Church shows by elaborate analyses and dietary tables, how this can be accomplished by various combinations of cereals, pulses, etc. He takes Forster and Voit's standard of 282 grains of nitrogen and 5,060 grains of carbon, with a suitable deduction for the smaller weight of the Indians. In his examples of daily rations he gives from 5 to 9 ounces of various beans, balanced by the addition of the proper quantity of rice—4 to 16 ounces, and a little oil. Such a large quantity of pulse appears to us excessive, and would cause discomfort to most persons. We much doubt whether those Indians who are strict vegetarians could consume such quantities.
Some valuable investigations were made on the diet of a family of fruitarians, at the Californian Agricultural Experimental Station, July, 1900, by Professor M.E. Jaffa (bulletin 107). The proportion of food, both proteid and carbo-hydrate used was surprisingly small. The research is particularly important, as the diet was not an experimental one, tried during a short period only; but that to which the family were accustomed. The family consisted of two women and three children; they had all been fruitarians for five to seven years, and made no change in their dietary during the experiment. They only had two meals a day, the food being eaten uncooked. The quantities of all the foods and other particulars are detailed in the bulletin. The first meal was at 10-30 a.m., and always consisted of nuts followed by fruits. The other meal was about 5 p.m., when they usually ate no nuts, substituting olive oil and honey. The nuts used were almonds, Brazil, pine, pignolias and walnuts; the fresh fruits were apples, apricots, bananas, figs, grapes, oranges, peaches and pears. Other foods were dates, raisins, pickled olives, olive oil and honey. One person (b) ate a little celery and tomatoes, and another (c) a little cereal food. In the following table are given the average daily quantities of the food constituents in grammes:—Proteids, fat, carbo-hydrate, crude fibre, value in calories and nutrient ratio. The crude fibre is classed as a carbo-hydrate and included in the calorie value, and also in calculating the nutrient ratio.
The last research extended over ten days; the period during which each of the other subjects was under observation was from 20 to 28 days.
(a) The tentative standard for a woman at light work calls for 90 grammes of proteids and 2,500 calories; it is thus seen that the quantity of food eaten was far below that usually stated as being necessary. The subject, however, was a very small woman, 5 feet in height, taking almost no physical exercise. She believed, as do fruitarians generally, that people need far less raw than cooked food. (b) The food eaten was even less in quantity than in the previous dietary. One reason for this was the fact that the subject was, for part of the time at least, under great mental strain, and did not have her usual appetite. Even this small amount of food, judging by her appearance and manner, seemed sufficient for her needs, enabling her to do her customary housework and take care of her two nieces and nephew, the subjects of the other experiments. (c) This girl was given cereals and vegetables when she craved them, but her aunt says she never looks nor feels so well when she has much starchy food, and returns to her next meal of uncooked food with an increased appreciation of its superiority. The commonly accepted dietary standard for a child 13 years old and of average activity, is not far from 90 grammes of proteids and 2,450 calories, yet the girl had all the appearance of being well fed and in excellent health and spirits. (d) During the 22 days of experiment, there was an increase in weight of 2 pounds, due to the fact that the family had been in straitened circumstances, and the food provided was more abundant during the study. (e) The subject had been very delicate as a baby. She was very small for her age, being 10 pounds under the average weight, and 7 inches less than the average height. It is interesting to note that her only gain in weight during the past year was made during this dietary and the one immediately following. This was due to her being urged to eat all she wanted, of what she most preferred, as the food was provided by those making the study. The proteid is less than the tentative standard for a child of 1 to 2 years old, but the subject appeared perfectly well and was exceedingly active. She impressed one as being a healthy child, but looked younger than her age. (ee) The subject is the same as in the previous experiment (e), but after an interval of 8 months, her seventh birthday occurred during the time.
Professor Jaffa, who made the investigation, says:—"It would appear that all the subjects were decidedly under-nourished, even making allowance for their light weight. But when we consider that the two adults have lived upon this diet for seven years, and think they are in better health and capable of more work than they ever were before, we hesitate to pronounce judgment. The three children had the appearance of health and strength. They ran and jumped and played all day like ordinary healthy children, and were said to be unusually free from colds and other complaints common to childhood. The youngest child, and the only one who has lived as a fruitarian almost from infancy was certainly undeveloped. She looked fully two years younger than she was. Still, there are so many children who are below the average in development, whose dietaries conform to the ordinary standards, that it would be unfair to draw any conclusions until many more such investigations are made."
The research shows that not only is there need of a revision of the "standard" quantity of proteids, but also of the carbo-hydrates and fats. It is generally said by those who have no practical experience amongst vegetarians, that the latter require a much larger quantity of food than do those who include flesh. The truth is that vegetarians eat less, often much less. It is a common experience that vegetable food has a more staying power, and a much longer period can be allowed between meals, without the inconvenience that a flesh-eater, especially a flesh and alcohol consumer, suffers. This is due, in part at least, to its less stimulating character and its slower digestion. This fact has been shown by the success of vegetarians in feats of strength and endurance, and especially in the comparatively fresh condition in which they have finished long walking, cycling, tennis, and other matches. Those who attempt to prolong their powers of endurance by flesh extracts and stimulating foods and drinks, usually finish in a very exhausted condition. The superior endurance and recovery from wounds, when compared with our English soldiers, of simple feeding men, such as the Zulus, Turks and Japanese, has often been remarked. It is often said that vegetable food, as it contains more fibre and is slower of digestion, taxes the bodily organs more. If we attempted to eat uncooked, the more fibrous vegetables, the grains, and unripe fruit, it would be quite true, but it is not so of the ordinary food of vegetarians. A slowness of digestion does not necessarily imply a greater strain on the system. As vegetables, in particular, are for the longest period of time in the intestines, and undergo the greater part of their digestion there, a gentle and slow process of digestion in that organ may be more thorough. It may also entail less expenditure of nervous energy than
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