World Resources 
expensive vegetable proteins which will include pulses and nuts 
it is possible to construct a diet which is very nearly satisfactory. 
But I have two pieces of evidence on the requirement of animal 
protein. First, starting with the International Nutrition Con- 
gress in 1953, there has been a series of papers published on 
vegans, that is to say, people who are vegetarians to the extent 
that they will touch no animal products. Everyone agrees that 
a simple lacto-ovo-vegetarian diet is perfectly healthy, but I 
think the evidence is absolutely incontrovertible that there is a 
serious deficiency of vitamin B,, in the diet of all vegans. 
Secondly, various groups have tried in the kwashiorkor con- 
text to determine the minimum amount of animal protein 
which is required to be added to predominantly cereal diets 
or whether in fact it is possible by mixing a variety of vegetable 
proteins to produce a food which is healthy for the post-weaning 
child. For those who are not familiar with this terminology, 
kwashiorkor is the most serious expression of protein malnutri- 
tion that we know: it is a very serious disease indeed which is 
invariably fatal if it is not corrected with suitable diet. Cure 
can be initiated in children with kwashiorkor if they are fed 
a purely vegetable diet, but it cannot be consolidated; such a 
diet cannot restore them to health. The nearest approach to 
this was made by the Scrimshaw group in Guatemala who 
devised a product known as “‘Incaparina”’ consisting of several 
vegetables mixed together. They claim that this purely vege- 
table diet is adequate for the maintenance of the post-weaning 
child. I am not convinced about this, however, because our 
own evidence does not support it. We find that we can main- 
tain or restore health if we add to the vegetable diet a 10 per 
cent admixture of fish meal or an 18 per cent admixture of milk 
protein skim-milk. So far as we are concerned we are able only 
to initiate cure with the vegetable diet, but we are not able to 
consolidate cure until we put the animal protein in. 
Clark referred to unidentified nutrients and in effect chal- 
lenged us to name them. They are, of course, certain of the 
essential amino acids. Looking forward to the future of man, 
there should be no difficulty in producing calories enough for 
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