A FANTASY ON AGEING AND THE BEARING 

 OF NUTRITION UPON IT 



R. A. McCaNCE, M.D., F.R.S., AND E. M. WiDDOWSON, D.Sc. 



Medical Research Council Department of Experimental Medicine, 

 University of Cambridge. 



The plane of nutrition has a profound effect on growth, 

 reproduction and the expectation of hfe. This is true not only 

 of complex organisms but also of protozoa: it may be true of 

 all cells. 



Actively growing rats, pigs and other animals have some 

 innate mechanism which adjusts their intake of food, and 

 consequently of calories, to their expenditure of energy. If 

 the diet at this level of intake does not contain enough 

 protein to satisfy their full demands for growth, the animals 

 do not grow at the maximum rate of which they are capable — 

 but they do not get fat. In an organism, however, without 

 this control over its "appetite" anything which limits growth 

 without interfering with the calorie intake leads to an accumu- 

 lation of storage material, ultimately in great excess. The 

 protozoa Tetrahymena for example can be grown in a synthetic 

 medium, and with Dr. Hamilton's help we have succeeded in 

 producing giant cells, full of fat, by giving a diet which pro- 

 vided plenty of calories but not enough protein to satisfy the 

 capacity for protoplasmic growth and cell multiplication 

 (McCance, 1953). We have also produced giants on the 

 normal — full protein — diets by stopping the multiplication 

 of the organisms with nitrogen mustard. One can play a 

 similar trick on unicellular green plants and make them very 

 obese by providing them with the facilities for photosyn- 

 thesis or for laying down reserve materials but no source 

 of nitrogen and inorganic salts. The material stored is 

 more variable In the green plants and may be fat (Fogg, 



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