16 The Composition and Food Value of Bread. 



Before discussing the results I should like to record my 

 thanks to both the donors of the flour, and to express my 

 appreciation of the keenness of the men who carried out the 

 experiment. Such work is extremely arduous. It entails no 

 little self-denial, and in the present case included 600 separate 

 weighings and over 1,000 chemical analyses. I wish also to 

 express my great indel)tedness to Sir Oswald Mosley's agent, 

 Mr. A. E. Beck, for the great trouble he has taken in preparing 

 the flours and in supplying information. 



A full account will be published later. For the present I 

 propose to give only the figures bearing on the subject of this 

 paper. In calculating the results it is assumed that all the 

 constituents of the milk, butter, and sugar are completely 

 digested, l^ut that since protein is not completely oxidised in 

 the body some of the energy of the protein of the milk will be 

 lost in the form of urea, &c., in the urine. This has been 

 estimated and allowed for in calculating the percentage of the 

 energy of the bread which was utilised. 



Comparing these figures with those given in Tal)le IV., 

 it is evident that the differences in digestibility of the various 

 constituents of the two kinds of bread are in the same direction 

 in both the American and the Cambridge experiments. Taking 

 the Camln-idge figures and calculating from them, and from the 

 figures for average composition of flours given in Table III., 

 the amounts of protein and energy which could be absorbed 

 from the ration of bread and flour commonly consumed bj^ the 

 working man, it appears that the amount of protein from white 

 ])read would l)e 56 grams, from 80 per cent, bread 57^ grams. 

 For the energy absorbed, the difference is only 9 units. These 

 differences are well inside the error of the various experi- 

 mental methods employed in determining them, and we may 

 conclude, therefore, from the Cambridge experiment, that the 

 slightly greater digestibility of white bread over (SO per cent, 

 bread practically balances the slightly lower content of protein, 

 and that as far as protein and energy are concerned it is 

 immaterial whether white or brown bread is used. If still 

 less husk is removed, there is a much greater fall in digestibility, 

 and the available protein and energy become smaller. 



Turning to the figures for phosphoric acid the case appears 

 to 1)6 quite different. The 80 per cent, bread used contained 

 rather more than twice as much phosphoric acid as the white 

 l)read. The percentage digested was exactly the same in the 

 two cases, 5,2 per cent. It follows, therefore, that the 80 per 

 cent, broad supplied to the tissues twice as much pliosphoric 

 acid per day as the white bread. Even with the lower 

 digestibility of the phosphorus of the coarser breads, their very 

 high contcut of this constituent ])laces more of it within reach 



