If one gulps down too much protein, it doesn’t go over into the body at all, but into the fecal waste matter. Even so, the body does get something from it: before it passes out, it lies there in the intestines and becomes poisonous and poisons the whole body. That’s what can happen from too much protein. And from this poisoning comes then very frequently arteriosclerosis — so that many people get arteriosclerosis too early, simply from stuffing themselves with too much protein.
It is important, as I have tried to show you, to know these things about nutrition. For most people are thoroughly convinced that the more they eat, the better they are nourished. Of course it is not true. One is often much better nourished if one eats less, because then one does not poison oneself.
The point is really that one must know how the various substances work. One must know that minerals work particularly on the head; carbohydrates — just as they are to be found in our most common foods, bread and potatoes, for instance — work more on the lung system and throat system (lungs, throat, palate and so on). Fats work particularly on heart and blood vessels, arteries and veins, and protein particularly on the abdominal organs. The head has no special amount of protein. What protein it does have — naturally, it also has to be nourished with protein, for after all, it consists of living substances — that protein man has to form himself. And if one over-eats, it’s no use believing that in that way one is getting a healthy brain, for just the opposite is happening: one is getting a poisoned brain.
Source: Rudolf Steiner – GA 354 – Nutrition and Health: Lecture 1 – Dornach, 31st July 1924
Translated by Gladys Hahn