446 ANNUAL REPORT SMITHSONIAN INSTITUTION, 195 7 



sure because, in the present era of cell physiology, the conclusion is 

 inescapable that inorganic materials play an important part in hor- 

 monal and enzymatic processes. Therefore, it seems not inappropriate 

 to discuss the role of sodium and potassium salts from this point of 

 view, although at this time the considerations are largely of a specula- 

 tive character. 



Theories which lay the groundwork for our own concepts were 

 gradually developed about 150 years ago. In a book which reveals a 

 remarkably modern outlook, Lehmann, in 1853, came to the conclusion 

 that the adding of salt to natural foodstuffs is unnecessary for man. 

 This view seemed to be supported by the fact that most animals, in 

 freedom and in captivity, do well on natural foodstuffs without addi- 

 tion of salt. Although some species (for example, cattle, deer, etc.) 

 consume salt eagerly when they are offered the substance or when they 

 encounter it in salt licks, there is no proof that they need it for a 

 healthy life. 



Later, however, von Bunge formulated his famous hypothesis that 

 extra dietary salt is needed by populations consuming predominantly 

 vegetable products. The excess salt was presumed to be necessary for 

 the more effective excretion of potassium. Bunge arrived at this con- 

 clusion on the basis of anthropological studies which he thought indi- 

 cated that nomadic societies mainly subsisting on meats do not add 

 salt to their food, whereas, once agriculture is developed, salting 

 becomes necessary. He linked this with his observation that the intake 

 of salt is accompanied by the rapid onset of potassium excretion. How- 

 ever, he emphasized that the large amounts of salt usually consumed are 

 out of proportion to what he thought are biological needs. Osborne 

 and Mendel later showed that salt requirements for growth of experi- 

 mental animals are indeed low; their animals were able to live on 

 traces of salt. Thus, one might have expected that this theory could 

 never have achieved major importance; but, curiously enough, this 

 has not been the case, and it is still cited without further discussion by 

 current textbooks of nutrition and anthropology. 



Objections to the theory should by now be all too obvious. So far 

 as the increased potassium excretion after salt intake is concerned, 

 such a reaction occurs unspecifically with many injuries and diseases. 

 Bunge himself never offered any proof that the increased potassium 

 excretion is biologically of advantage, although he implied it. Now 

 we might be inclined to the opinion that these potassium losses are 

 disadvantageous. 



As for Bunge's anthropological data, he brushed away the objection 

 that some African tribes mainly subsisting on a vegetarian diet use 

 potassium-rich plant ashes rather than salt as a condiment. Even at 

 the present time there exist a considerable number of societies which do 





