HOW FOODS MEET BODY NEEDS. 3 
phosphorus, and iron are slightly higher than what is considered a 
minimum requirement to cover possible waste and lack of utilization. 
The needs of a man at moderately active muscular work are almost 
universally adopted as the unit for measuring food needs, and for 
this reason they are used in this publication. For some persons, it 
may be more to the point to know what percentage a given food sup- 
plies of the nutrients needed by the average adult, by the average 
family, or by some other individual or group. To change the per- 
centages so that they will apply to the needs of the average adult, the 
man doing little or no muscular work, or the woman doing moder- 
ately active muscular work, they need only to be increased one-fourth. 
This must not be taken to mean that the man doing little or no work 
needs one-fourth more food than the man doing active work, but that 
he derives a higher proportion of the food needs of his body from a 
pound of a given food. For the woman doing little or no muscular 
work, they should be increased one-half. For the average family, 
which is supposed to consist of a man and a woman, both doing 
moderately active muscular work, and three young children, they 
should be only three-tenths as great. For example, a pound of oat- 
meal, which supplies 52 per cent of the fuel needed daily by a man 
at moderately active work, will supply 65 (1^X52) per cent of the 
fuel needed by the average adult, 78 (1JX52) per cent of the fuel 
needed by a woman who does little or no muscular work, and about 
16 (to X52) per cent of the fuel needed by the average family. More 
detailed information on working out the energy requirements of 
various individuals and families is given in other publications of 
this department. 1 
The charts will be found useful in various ways. The heavy lines, 
even without the figures that accompany them, show for what con- 
stituents the various foods are specially valuable. For example, the 
comparatively long lines representing iron in spinach, calcium in 
cheese, fuel in butter, phosphorus in peanuts, and protein in such 
foods as milk, eggs, and meat, show at a glance the nutrients in which 
these foods are rich. 
The lines and figures also furnish an easy means of comparing one 
food with another. The energy lines on the sweet and Irish potato 
charts, for instance, show that the former has a higher fuel value. 
The protein lines on the oatmeal and rice charts show that as a source 
of protein, oatmeal excels rice. The calcium lines on the string bean 
and tomato charts show that the former is richer than the latter in 
lime. The phosphorus lines in corn and spinach show that corn is 
richer in this particular element. The iron line in lettuce as cbm- 
1 U. S. Dept. Agr., Farmers' Bui. 142, Principles of Nutrition and Nutritive Value of 
Food ; Farmers' Bui. 1228, A Week's Food for an Average Family. 
