The Chemistry of Food and Nutrition

by A. W. Duncan

Some comments may now be made upon the table of dietaries. That of the London sewing girl contained 53 grammes of proteid, which should have been ample, according to some of the authorities we have given; yet she was badly nourished. The food was doubtless of bad quality, and it appears deficient in carbo-hydrates; this latter is shown by the low number of calories. The long hours and unhealthy conditions of work, and not a deficiency of food constituents, is probably the cause of the bad health of such persons. There is no reason to think the proteid insufficient, although some persons have said as much. We have no particulars of the German vegetarians, but the calories appear satisfactory. In the poor German labourer's family the calories are too low. In Dr. T.R. Allinson's experiment on a wheatmeal dietary, it will not do to assume that less than 82 grammes of proteid would have been insufficient. It is probable that a smaller quantity of proteid would have been enough if the fat and carbohydrates had been increased. The calories are below the usual standard. In the succeeding example the calories are considerably higher, being not far from the usual standard, yet 54 grammes of proteid sufficed. It is a common error to place an undue value on the proteids to the extent of overlooking the other constituents. Dr. Alexander Haig in "Diet and Food," p. 8, cites the case of a boy aged 10, fed on 2¼ pints of milk per day. The boy lost weight, and Dr. Haig is of opinion that the quantity of milk was very deficient in proteid; more than twice as much being required. 2¼ pints of milk contain about 45 grammes of proteid, whereas, according to the usual figures (125 x 6/10) a boy of this age requires 75 g. This quantity of 45 g. is however, higher, allowing for the boy's age, than that in several of the dietaries we have given in our table. A little consideration will show that Dr. Haig has overlooked the serious deficiency of the milk in the other constituents, which accounts for the boy's loss of weight. The quantity of milk contains only about 160 g. of total solid matter, whilst 400 g. is the necessary quantity. Milk is too rich in proteid matter to form, with advantage, the sole food of a human being. Human milk contains much less in proportion to the other constituents.

The old doctrine enunciated by Justus von Liebig was that proteid matter is the principal source of muscular energy or strength. He afterwards discovered and acknowledged his error, and the subject has since been thoroughly investigated. The makers of meat extracts and other foods, either from their own ignorance of modern research or their wish to take advantage of the lack of knowledge and prejudice of the public, call proteid matter alone nourishment. The carbo-hydrates and fats are equally entitled to be called nourishment.

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 if the food had been of such a stimulating character, as to be hurried along the digestive tract. Digestion is for the most part a chemical process. If the food is of right kind and quantity, thoroughly masticated, assisted if necessary by cookery, and the digestive ferments are normal, digestion proceeds without any sensible expenditure or energy or consciousness of its accomplishment. There is nothing improbable in a flesh-eater requiring more food than a simple living vegetarian. His food contains more proteid, and excrementitious matter or extractives; these stimulate the digestive organs and overtax the excretory ones. Generally, he is fond of condiments, salt, and elaborate cooking, often also of alcohol; if a man, probably of tobacco. He lives, as it were, at high pressure.