3. Salts and minerals (such as phosphates, lime, iron, citrates,
etc.) to build bones and teeth, feed the brain and nerves, and
purify the body.
No hard-and-fast table or rule can be laid down concerning the proper
proportions in which these elements should be combined, because the
amount needful for each individual varies according to his size, the
sort of work he does, the amount of physical or mental energy he puts
forth, and the temperature of the atmosphere surrounding him.
Until Professor Chittenden made his extensive and conclusive series of
experiments in America, in 1903-4, to determine the real amount of
Protein and other elements required to keep the body in perfect
health, the average estimate for a person of average size, who does a
moderate amount of physical labour, was about 4-ozs. of Protein per
day.
But these official experiments, conducted with scientific precision,
extending over a long period, and made with thirty-four typical and
carefully graded representatives of physical and mental work,
demonstrated that half this amount of Protein is sufficient, and that
strength and health are increased when the quantity is thus reduced;
also that a smaller amount of Carbohydrate food (bread, etc.), than
was previously thought necessary, is enough.
One may therefore now safely reckon that men of average size and
weight (say 10 to 12 stone) doing a moderate amount of physical and
mental work, can thrive under ordinary circumstances on a daily ration
containing about 800 grains of Protein (nearly 2 ozs).
The following food chart will enable the reader to calculate
(approximately) how much food of any particular kind is necessary to
provide the above amount. Adult persons below the average size and
weight, and living sedentary rather than an active physical life, will
naturally require less than this normal standard. The relative cost
and economy of the different foods can also thus be ascertained.
If care is taken to secure a sufficient quantity of Protein the
requisite amount of Carbohydrates is not likely to be omitted, and
hunger will prove a reliable guide in most cases. It is advisable,
however, to see that enough Fat is taken, especially in winter, and by
persons lacking in nerve force.
The table of food-values will easily enable the reader to ascertain
the proportion of Fat in each kind of food.