"Bread may be made out of wheat flour, water, , and salt. Even when it contains no other ingredients than these, it has not always the same food value, pound for pound, for flours themselves differ in composition, and, moreover, some flours take up more water than others, the result being moister bread. Sometimes a little sugar or fat is added to the ingredients, and milk is often substituted for part of the water. These substances contribute somewhat to the nutritive valued of the bread, but they are used in such small amounts that they are much less important than the flour. The food value of a pound of bread is, therefore, not far different from that of the flour used in making it."