xample: if milk is 5 cents per quart, two
quarts or approximately four pounds, can be procured for 10 cents. If
the milk contains fat, 4 per cent, protein, 3.3 per cent, carbohydrates,
5 per cent, and fuel value, 310 calories per pound, multiplying each of
these by 4 gives the nutrients and fuel value in four pounds, or 10
cents worth of milk, as follows:

Protein 0.13 lb.
Fat 0.16 lb.
Carbohydrates 0.2 lb.
Calories 1240

If it is desired to compare milk at 5 cents per quart with round steak
at 15 cents per pound, 10 cents will procure 0.66, or two thirds of a
pound of round steak containing on an average (edible portion) 19 per
cent protein, 12.8 per cent fat, and yielding 890 calories per pound. If
10 per cent is refuse, there is edible about 0.6 of a pound. The amounts
of nutrients in the 0.6 of a pound of steak, edible portion, or 0.66 lb.
as purchased would be:

Protein 0.11 lb.
Fat 0.08 lb.
Calories 534

It is to be observed that from the 10 cents' worth of milk a little more
protein, 0.08 of a pound more fat, and nearly two and one half times as
many calories can be secured as from the 10 cents' worth of meat. This
is due to the carbohydrates and the larger amount of fat which the milk
contains. At these prices, milk should be used liberally in the dietary,
as it furnishes more of all the nutrients than does meat. It would not
be advisable to exclude meat entirely from the ration, but milk at 5
cents per quart is cheaper food than meat at 15 cents per pound. In
making comparisons, preference cannot always be given to one food
because of its containing more of any particular nutrient, for often
there are other factors that influence the value.

243. Comparing Foods as to Nutritive Value.--In general, preference
should be given to foods which supply the most protein, provided the
differences between the carbohydrates and fats are not large. When the
protein content of two foods is nearly the same, but the fats and
carbohydrates differ materially, the preference may safely be given to
the food which supplies the larger amount of total nutrients. A pound of
protein in a ration is more valuable than a pound of either fat or
carbohydrates, although it is not possible to establish an absolute
scale as to the comparative value of these nutrients, because they serve
different functional purposes in the body. It is sometimes n