The Chemistry of Food and Nutrition - A. W. Duncan (latest books to read .TXT) 📗

Dr. Alexander Haig considers that 88 grammes of proteid is required by a man leading a decidedly active life.

NOTES.—(a) The Japanese are of small stature and weight.

(b) One of a series of experiments by A.W. Blyth, 1888. 1½ lbs. of wheatmeal per day was required for equilibrium; sedentary occupation, with a daily walk of six miles.

(c) See "A Text Book of Physiology," by M. Foster, 5th edition, part ii., p. 839; the diet was bread, fruit and oil. The man was in apparently good health and stationary weight; only 59 per cent. of the proteids were digested, leaving the small quantity of 32 grammes available for real use. In commenting upon this, Professor Foster writes:—"We cannot authoritatively say that such a reduction is necessarily an evil; for our knowledge will not at present permit us to make an authoritative exact statement as to the extent to which the proteid may be reduced without disadvantage to the body, when accompanied by adequate provision of the other elements of food; and this statement holds good whether the body be undertaking a small or large amount of labour."

(d) The Miller of Billericay's case is quoted by Dr. Carpenter, and also by Dr. Pavy. It was reported to the College of Physicians in 1767 by Sir George Baker. A remarkable degree of vigour is said to have been sustained for upwards of eighteen years on no other nutriment than 16 oz. of flour, made into a pudding with water, no other liquid of any kind being taken.

A striking instance of abstemiousness is that of Cornaro, a Venetian nobleman, who died in the year 1566 at the age of 98. Up to the age of 40 he spent a life of indulgence, eating and drinking to excess. At this time, having been endowed with a feeble constitution, he was suffering from dyspepsia, gout, and an almost continual slow fever, with an intolerable thirst continually hanging upon him. The skill of the best physicians of Italy was unavailing. At length he completely changed his habits of diet, and made a complete recovery. At the age of 83 he wrote a treatise on a "Sure and certain method of attaining a long and healthful life." He says, what with bread, meat, the yolk of an egg and soup, I ate as much as weighed 12 ozs., neither more nor less. I drank 14 oz. of wine. When 78 he was persuaded to increase his food by the addition of 2 oz. per day, and this nearly proved fatal. He writes that, instead of old age being one of weakness, infirmity and misery, I find myself to be in the most pleasant and delightful stage of life. At 83 I am always merry, maintaining a happy peace in my own mind. A sober life has preserved me in that sprightliness of thought and gaiety of humour. My teeth are all as sound as in my youth. He was able to take moderate exercise in riding and walking at that age. He was very passionate and hasty in his youth. He wrote other treatises up to the age of 95.

Kumagara, Lapicque and Breis-acher, have, as the result of their experiments, reduced the quantity of proteid required per 24 hours to 45 grammes. T. Hirschfeld states, as the conclusion of his research, that it is possible for a healthy man (in one case for 15 days and in another for 10 days) to maintain nitrogenous balance on from 30 to 40 grammes of proteid per day. Labbé and Morchoisne (Comptes Rendus, 30th May, 1904, p. 1365) made a dieting experiment during 38 days, upon one of themselves. The proteid was derived exclusively from vegetable food. The food consisted of bread, lentils, haricots, potatoes, carrots, chestnuts, endives, apples, oranges, preserves, sugar, starch, butter, chocolate and wine. At the commencement, the day's food contained 14.1 grammes of nitrogen = 89.3 proteid, which was gradually diminished. On the 7th day 11.6 g. N. = 73.5 g. proteid was reached; during this time less N. was eliminated, indicating that the proteid food was in excess of that required for the wear and tear of the body. As the quantity of nitrogenous food was diminished almost daily, the N. eliminated was found to diminish also. This latter was in slight excess of that absorbed; but when a day or two's time was allowed, without further reduction in the food, the body tended to adjust itself to the dimished supply, and there was an approximation of income and expenditure. The smallest quantity of food was reached on the 32nd day with 1.06 N. = 6.7 proteid, which was obviously too little, as 2.19 N. = 13.9 proteid was eliminated. On the 21st day 4.12 N. = 26 proteid was injested, and 4.05 N. was eliminated. The inference drawn from the research is that about 26 grammes of proteid per day was sufficient. The weight of the body remained practically constant throughout, and the subject did not suffer inconvenience. Of course the full amount of calories was kept up; as each succeeding quantity of the proteid was left off, it was replaced by a proper quantity of non-nitrogenous food. These experiments were carried out in the usual approved scientific manner. It may, however, be urged against any generalised and positive conclusions as to the minimum quantity of proteid required for the body, being drawn from such experiments, that the period covered by them was much too short. A prolonged trial might have revealed some obscure physiological derangement. We are quite justified in concluding that the usual, so-called "standard dietaries" contain an unnecessarily large proportion of proteid. In some practical dietaries, 50 grammes and under have seemed enough; but for the ordinary adult man, who has been accustomed to an abundance of proteid, and whose ancestors have also, it is probably advisable not to take less than 70 or 80 grammes per day (2½ to 3 ounces). If it is desired to try less, the diminution should be very gradual, and a watch should be kept for any lessening of strength.

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