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PHYSIOLOGY: LA NGWORTHY AND HOLMES Proc. N.-A. S. 
order to have under observation individuals whose peristaltic action was 
normal and regular and others who had a tendency toward constipation. 
Summary of Results. — The results obtained in the studies of 54%, 
70%, 85%, and 100% flours are summarized in the table which follows: 
TABLE 5 
Summary of Experiments on the Digestibility of Wheat Flours 
KIND OK FLOUR 
USED IN PREPARA- 
TION OF BREAD 
NUMBER 
OF 
EXPTS. 
AVERAGE 
AMOUNT 
OF BREAD 
EATEN 
PER MAN 
PER DAY 
DIGESTIBILITY OF ENTIRE RATION 
DIGESTI- 
BILITY OF 
BREAD 
PROTEIN 
DIGESTI- 
BILITY OF 
BREAD 
CARBO- 
HYDRATE 
PROTEIN 
FAT 
CARBO- 
HYDRATE 
GRAMS 
PER CENT 
PER CENT 
PER CENT 
PER CENT 
PER CENT 
54% flour 
43 
600 
87.8 
96.5 
98.8 
87.7 
99.7 
70% flour 
42 
564 
90.1 
96.1 
99.0 
90.1 
99.9 
85% flour 
21 
472 
87.1 
96.9 
97.5 
87.1 
98.5 
100% flour 
33 
663 
84.2 
93.9 
95.0 
84.2 
94.4 
In the above experiments the subjects ate on an average considerably 
more than a pound of bread daily for periods of from 6 to 20 days without 
producing any digestive disturbances, which indicates that wheat flours, 
regardless of percentage of extraction, are well tolerated by the human body. 
The coefficients of digestibility, obtained from the 139 digestion ex- 
periments reported above, 87.7% for protein and 99.7% for carbohydrate 
of 54% flour; 90.1% for protein and 99.9% for carbohydrate of 70% flour 
(95% patent); 87.1% for protein and 98.5% for carbohydrate of 85% 
("whole wheat") flour; and 84.2% for protein and 94.4% for carbohydrate 
of 100% flour, show these flours to be well digested. From these results 
it appears that the U. S. Food Administration in attempting to obtain 
efficient utilization of the wheat supply secured did well to specify that 
wheat should be milled at 75% extraction, that is an extraction similar 
to the one which in these experiments showed the highest proportion of 
digestible nutrients. 
The digestibility of the fat content of the experimental diet was quite 
uniform and was practically identical with that of butter and "shortening" 6 
which comprised the major portion of the fat consumed, except in the series 
of experiments with 100% flour in which the fat was only 93.7% digested. 
Attention was given to the effect of the different flours on peristaltic 
action. The 54% and 70% flours did not tend to produce constipation 
during a period of 15 to 18 days, and although a somewhat freer movement 
of the bowels resulted from the continued use of 85% and 100% flours 
no case of pronounced laxative effect was noted. 
