In the late nineteenth century. Baron von Liebig was the first person to separate foods into proteins (nitrogenous substances) and carbohydrates/fats (non-nitrogenous substances). Since the muscles are composed chiefly of protein. Liebig concluded (incorrectly) that proteins supply muscular energy and the amount of protein consumed must be related to bodily activity. In fact, it is actually the non-nitrogenous foods that supply the best fuel for muscular activity.
Liebig was one of the first scientists to make a recommendation for protein intake. He determined the body’s protein requirements by measuring the actual amounts of protein consumed by a group of men engaged in physical activity who ate a heavy diet. He reasoned that by measuring the protein intake of men who ate more than average and worked harder than usual, he could arrive at a safe recommended allowance of protein for all people. Such a technique for establishing a standard is somewhat akin to clocking race car drivers in order to establish a safe speed for school zones.
Anyway, based on this experiment Liebig determined that about 120 grams of protein daily would satisfy the needs of a moderately active adult. To obtain 120 grams of protein, a person would need to consume about 17 eggs or a pound and a half of meat or twenty ounces of almonds per day.
Following Liebig, Voit in 1881 performed a series of experiments on dogs and likewise determined that we should consume between 100 and 125 grams of protein a day. Doubtless, dogs can safely consume 125 grams of protein per day. The protein requirement for a growing puppy is five times as great as that for a growing baby. Voit, unfortunately, did not adjust his results to account for the differences between humans and dogs. From the very beginning, we can see that protein requirements were artificially determined and excessively high. As early as 1887, experiments in Germany showed that 40 grams of protein was a sufficient daily amount about one-third of the current recommendations. The old standards of Liebig and Voit, however, were already firmly fixed in the minds of the medical establishment, and the belief persisted that a high-protein diet was conducive to health anyway, so why lower the recommendations?
After many more experiments proved that a daily protein intake of 30 to 40 grams was entirely sufficient, the establishment finally revised its recommendations down to 60 or 70 grams. Although only one-half of the early estimates, this figure is 50% too high, even by conservative nutritional standards. Today, with the support of the meat, dairy and egg industries, the protein allowances still remain around 70 grams per day. It should also be noted that a typical American meat-eater consumes about 93 grams of protein daily—more than anyone else in the world on the average.