1920.] 



Our National Food Supply. 



133 



OUR NATIONAL FOOD SUPPLY: 



LIMITS OF SELF SUPPORT. 



The following notes are an abstract of the first of three 

 Chadwick Lectures dehvered at the Royal Sanitary Institute 

 by Sir Daniel Hall, K.C.B., F.R.S., :— 



It is well known that of late years the United Kingdom has 

 been very largely dependent upon imported food to maintain 

 its population. To what extent do we feed ourselves ? In 

 order to obtain comparable figures it is necessary to reduce 

 all foods to a common standard. Mere weight will not com- 

 pare bacon with bread or eggs with milk. The common 

 standard we require is obtained by ascertaining the value of 

 the food as fuel to keep the machine of the body running. The 

 body behaves hke a machine ; it takes in food just as an engine 

 requires coal, and the more work the body does the more fuel 

 must be burnt up in it. Scientific men, therefore, value food 

 in units called calories, which measure the value of the food 

 as a means of doing work. There are other elements in food 

 to be considered, particularly the protein content, protein 

 being required to repair the waste of the tissues. But in an 

 ordinary mixed diet if the calories are sufficient to keep the 

 machine running the food will also supply enough protein. A 

 man doing light work will want about 3,000 calories a day. 



Towards the end of 1916, when the question of the nation's 

 food supply began to be urgent, a Committee of the Royal 

 Society summed up the diet of the nation for the five-year period 

 prior to the War, and according to its figures in those years 

 the total food supply consumed would have supplied each man, 

 woman and child in the United Kingdom with 3,091 calories 

 a day.* Only about 42 per cent., however, of this food was 

 produced within the United Kingdom. Of the most important 

 elements in the food of the country, i.e., bread, only one-fifth 

 was produced at home, but something like 60 per cent, of the 

 meat and nearly all the potatoes were grown here. 



How did we get into this dangerous position ? At the 

 beginning of the Nineteenth Century the country was prac- 

 tically self-supporting, but the growth of population had alto- 

 gether outstripped the increased productivity of the land. 

 Moreover, for the period of forty years before the War the pro- 

 ductivity of the land had been steadily decUning owing to 



* See this Journal, February, 191 7, p. 1046. 



