VITAMINS 



161 



ism of action I mean what a particular 

 molecule does in the cell, on what molecule 

 of the cell it acts, and in what way it acts. 

 With these biologically active substances 

 we can produce the most wonderful effects 

 — we can resuscitate the dead, transform 

 the male into the female, and vice versa, 

 inject a pennyw^orth of mother-love, etc., 

 etc. — but we have no idea what we have 

 really done. The physiologist producing 

 such wonderful reactions with his active 

 substances reminds me of the savage who, 

 with his penny, produces wonderful music 

 from a music box. 



This coexistence of the most wonderful 

 success wdth the most profound ignorance 

 is one of the characteristic features of pres- 

 ent-day biology. It can easily be under- 

 stood. To produce the effect we need only 

 to have the substance and to put it into the 

 animal. To understand its action we must 

 understand both partners of the bargain, 

 the active substance and the cell on which 

 it acts; that is, the penny and the music 

 box. "We know all about the first, the active 

 substance, but next to nothing about proto- 

 plasmic structure. 



We must not be misled by appearances. 

 You will find a huge literature on the ac- 

 tion of vitamins. The symptoms of vi- 

 tamin deficiencies have been carefully 

 studied, and it seems as if we completely 

 understand how the lack of a vitamin pro- 

 duces those symptoms and how the vitamin 

 cures them. So, for instance, in Bi avi- 

 taminosis we find ataxia and paralysis. 

 The vitaminologist studies the brain and 

 finds polyneuritis and structural lesions 

 which fully explain all the observed symp- 

 toms. Now he administers vitamin Bi to 

 the animal and sees that the symptoms and 

 lesions disappear, and is satisfied that he 

 has explained the whole action. He calls 

 his vitamin the * ' antineuritic vitamin," a 

 name which suggests that the substance is 

 there to keep neuritis away. But a brief 

 consideration tells us that this impression 

 is wrong. Rice bran and yeast are both 

 rich in vitamin Bi, and neither of these 

 has brains. So it cannot be the sole object 

 of aneurin (Bi) to prevent the occurrence 

 of polyneuritis. 



This whole problem has been solved 

 lately by a discovery of K. Lohmann, who 

 found that the coenzyme of decarboxyla- 

 tion of pyruvic acid is phosphorylated vita- 

 min Bi. Now decarboxylation of pyruvic 

 acid is one of the most basic chemical re- 

 actions throughout living nature. Natur- 

 ally, if a basic chemical reaction goes 

 wrong there will be one organ which shows 

 injury first. So, for instance, if I don't 

 breathe I will faint, and my brain will be 

 the first organ to declare itself. This does 

 not mean, however, that oxygen is a neuro- 

 tropic substance. So if vitamin-Bi defici- 

 ency has its greatest effect on the brain, 

 this does not mean that vitamin Bi is a 

 specific constituent of the nervous tissue. 

 The symptoms we see in the animal tell us 

 practically nothing about the real mode of 

 action of a substance. A few years ago 

 two Americans, Burr and Burr, found that 

 the rat would lose its tail if highly un- 

 saturated higher fatty acids were missing 

 from its diet. It looked as if an "anti-tail- 

 drop-off" vitamin had been discovered. 

 Naturally it is not the function of the un- 

 saturated fatty acids to stick the tail to its 

 place by their double bonds. Both vitamin 

 Bi and fatty acids have some basic function 

 in the cell. Whether it will be the head end 

 or the tail end of the animal which is af- 

 fected first gives us little information about 

 the real mode of action, as ataxia tells us 

 nothing about decarboxylation. 



It is very important to remember that 

 all these vitamins are not specific sub- 

 stances, present to prevent some specific 

 disease of some specific tissue. They are 

 basic constituents of the cell — all cells, ani- 

 mal and vegetable — and symptoms like 

 capillary fragility, or loosening of teeth 

 give us no information about this basic 

 function. 



We are well informed about the mechan- 

 ism of action of only a few biologically 

 active substances. These are substances 

 that happen to act in cell functions which 

 are sufficiently understood. One of the 

 processes which has perhaps been analyzed 

 most of all cellular processes is biological 

 oxidation. This process is fairly well 

 known, partly because it is a violent re- 



