"Liebig conceived the idea that albumens and proteins are needed in direct proportion to a man's or woman's activity."
Ever since it was decided that protein is the most important and most essential part of our food, there has raged a controversy over how much protein a day is required to meet the needs of man. At first, the efforts to determine the amount of protein needed were made by merely striking an average of the amount of protein actually eaten by certain groups of men, who are now known to have been gluttonous eaters. Next, an effort was made to determine the amount of protein needed by experiments on dogs. Imagine, trying to discover the protein needs of man by making tests on dogs!
More than seventy years ago Liebig conceived the idea that albumens and proteins are needed in direct proportion to a man's or woman's activity. He thought that the human body is run on the substances of which its muscles and viscera are composed. Of this notion, Drinkwater says: "If muscles are worn away by exercise of their normal function, according to the old view, it would be like a locomotive having to have its wheels and machinery renewed at the end of each journey, instead of needing simply water and fuel." (Food in Health and Disease, London, 1906.)
Following Liebig, Voight declared in 1881 that man requires twenty percent of his daily diet to be protein. A little later Atwater made it twenty-five percent, and Moleschott and Veirordt made it twenty percent. Voight experimented upon dogs in his effort to determine the protein requirements of man.
These standards demanded for the adult, who has ceased growing, 7% to 12% more protein (more tissue building material) than nature herself provides for an infant which doubles its weight in six months and trebles its weight in a year. Not until Lahmann in 1892 appreciated this discrepancy and set about to determine the proportions of protein, carbohydrate, fat and salts in mother's milk, and used this information as a basis for calculation for adult diets, was a really decisive blow struck at the old school of dietetics. Lahmann was an old school physician who had associated himself with Louis Kuhne. He noticed that Kuhne's patients, fed as they were on fruits and vegetables, were not receiving the "required" amounts of protein, but fared well on their low protein diet.
Analyzing the ingredients of dried milk, that is water free milk he found that the fat, sugar and minerals amounted to 85.5 percent of the whole; the protein present amounted to only 13.5 percent. Thus for a growing baby, producing more tissue daily than does the adult, nature provides a diet, which, apart from water, contains only 13.5 percent of the tissue building material called protein. But relative to the total bulk of breast milk taken by an infant, the pro-tein is really only 1.6 percent, because it is 88 percent water. Only in relation to the ingredients other than water is the amount 13.5 percent. This is said, however, not to be wholly a reliable basis of calculation, because unless we know the adult's activity as compared with that of the baby, we cannot accurately assess the adult's need.
Drinkwater says that "the most strenuous muscular labour does not increase in the smallest degree the metabolism of albuminates (proteins) in the body; it is the non-nitrogeneous alimentary principles, the fats and carbohydrates, whose consumption is increased by muscular activity." It would seem, therefore, that our need in accurately assessing the protein needs of the adult as compared to that of the infant, would be a knowledge of the relative differences in tissue building activity that goes on in the two organisms.
"Men are poisoned by excessive protein ingestion."
Lahmann was in favor of conforming to the proportion of milk. This was too high, particularly as he used cow's milk as his standard. Chittenden maintained that "body-weight, health, strength, mental and physical vigor and endurance can be maintained with at least one-half of the protein food ordinarily consumed." He estimated the proportion of protein for the adult at 3.5 percent lower than for the infant, and thought that health could be maintained much more satisfactorily on about 10 percent of protein in the diet than on 20 percent.
30 g - 1923
It was later found that the estimates of both Lahmann and of Chittenden are much in excess of actual body needs, for active grown men. Boyd, taking flesh as the source of protein, estimated the minimum daily ration of protein requisite to maintain body-weight at 30 grammes, i.e., only 4.65 percent in a total amount of 650 grammes of food.
58 g/kg per day - 1920's
After carefully surveying all previous estimates and after conscientious experimentation of his own, Berg came to the conclusion that the adult body's need of protein should be calculated on a basis of .58 grammes per kilogramme of body weight (Vitamins). Berg concluded that "a supply equivalent to 1 gramme of protein per kilogramme of body-weight, when a mixed diet is taken . . . provides a margin of safety of from 50 to 100 percent."
Thus a fully grown adult, of say 140 lbs. should consume not more than 2.2 ounces of protein a day—i.e., if he is taking his protein in the form of meat or cheese, he should not take more than half a pound of beef or curd cheese altogether; or if he is taking it in the form of cod-fish, not more than 7/8 of a pound. (14 oz)
(Note: 1 ounce/oz = 28.47 g, 1 lb = 0.45 kg)
It is obvious that the average full-grown man, even of moderate habits, allows himself a much larger proportion of protein. If he has eggs and bacon for breakfast, these alone, apart from the bread he consumes with them, will provide 3/5 of his daily quota of 2.2 ounces of protein, leaving only 1.6 ounces for his lunch an dinner. Thus, by the time he has his lunch, consisting of a cut from a joint, a chop or a steak, he has consumed more than his quota, and the rest is all excess as far as protein is concerned, quite apart from the bread, potatoes, milk or cereals he may also have had.
Ragnar Berg allows a small increase of protein for reproduction, and in this case proteins of high biological value are essential. But when reproduction is allowed for, it is obvious from the previous figures that the average man who has ceased growing, indulges to excess in those kinds of foods which are body building and which he does not require, and thus, not only deprives his body of other important elements, such as mineral salts and vitamins, but also impedes the combustion of his running fuel. Hindhede reared four athletic and wide-awake children on a diet so low in protein that it has been said "it would frighten a school teacher into blind staggers."
1 g/kg per day - 1968
The British Association for the Advancement of Science was addressed at its regular meeting about two years ago by a Swiss speaker, Prof. A. Fleisch. He told the assembled scientists that experiments carried out with scientific thoroughness on 4,000,000 people in Switzerland showed that the amounts of calories, proteins and fats formerly considered essential in civilized countries were utterly unnecessary. He asserted, on the basis of these experiments, that the United Nations minimum standard of 2,400 calories a day is too much and that 2,160 is sufficient for all except heavy manual workers. The conclusion reached through their experiments is that one gramme of protein per kilo (0.035 oz. per 2 1/4 lb.) of body weight is correct. Before the war the protein requirements were supposed to be 100 grammes (3 1/2 oz.). This amount he asserted, was not only unnecessary, but was actually harmful. He said that a large part of the meat and eggs eaten before the war and a large part of the refined fats, sugar and white bread and macaroni could have been replaced by vegetables, fruits and darker bread,
Finally, be said that today, when great nations of the world are suffering from hunger, it is absolute waste to convert large quantities of wheat into eggs, thus losing 90 percent of the nutritive value of the wheat, and to convert tremendous amounts of maize (corn) and barley into fodder (food for cows) and thus lose 75 percent of the calories and proteins. This is a direct stab at our traditional but nonetheless foolish agriculture which first raises huge quantities of food for animals, feeds it to the animals, and then feeds man a small percentage of the food value thus converted into animal foods.
"Only about one-half the amount of protein considered necessary before the war is needed daily by the individual for health and strength."
It will seem amazing to most of my readers that only about one-half the amount of protein considered necessary before the war is needed daily by the individual for health and strength. The old high protein standards thus go glimmering through the things that were. No doubt the packers and the poultry men will not like this and a great howl will go up from the rat pens. The radio touts who look after the interests of the meat packing industry will shout themselves hoarse denying the validity of these tests made on men and women instead of rats. Nonetheless, there is but one way to determine the nutritive requirements of man. In dealing with the young, the requirements of a rapidly growing animal and those of an animal of slow growth are very different.
While the efforts of most investigators seem to have been directed to ascertaining minimum protein requirements, it may be debatable as to whether or not this can establish a valid standard for protein intake. It is quite clear, however, that greater sobriety in the matter of nitrogen (protein) ingestion is essential not only to achieve a return to health, but also in order to maintain health at its highest peak at all times and for all purposes. Reinheimer truly says that "nitrogen, the chief ingredient of protein, is universally a good servant, but a bad master." It is well known to physiologists that both fat and protein metabolism depend upon carbohydrate metabolism. There is a delicate balance between carbohydrates and proteins, to which we have to conform - disease and degeneration resulting from failure to conform.
It has been shown that excess nitrogen is detrimental to the capacity for work, while very generally, it is the accumulation of a nitrogen product, kinotoxin, in the muscles that is the cause of fatigue. Men are poisoned by excessive protein ingestion. More than any other food factor, excesses of protein foods fill the body with toxins. Indeed, the whole system becomes overcharged with poisonous products of protein metabolism, which the eliminative functions eventually fail to cope with. The calamitous moribundity of a body poisoned by unsuitable and excessive protein is similar to the case of alimentary anaphylaxis.
"Greater sobriety in the matter of protein ingestion is essential, not only to achieve a return to health, but also in order to maintain health at its highest peak."
In middle aged adults, perfectly normal kidneys are the exception rather than the rule. By a careful selection of a low nitrogen diet, it is possible to reduce the amount of work required of the kidneys to a level at which they are able to keep the waste products in the blood within normal limits.
We can say, without fear of successful contradiction, that a disproportionately increased amount of protein in the diet, due to the arbitrary addition to the diet of foods rich in protein, such as flesh, eggs, cheese, etc., proves harmful, as a continual excess of protein results in severe disturbances of health. Yet these are the very foods that the advocates of much "high-grade" protein place greatest stress upon. An excess of protein thus provided, (this improperly prepared and wrongly combined), is the source of much trouble.