But what bearing has all this upon the dietetic use of nuts? The relation is very direct and very important. The situation developed as a result of the World War made very clear to everybody how close the world has arrived to the point where the careful economizing of our food resources will be absolutely necessary. The rapid increase of the world's population which has occurred, especially within the last two centuries, is a hew world experience. Two hundred years ago the average length of human life was less than 20 years, as it still is in Mexico and some other parts of the world where the life-saving influence of modern sanitation and health conservation have not had an opportunity to exercise their influence. In former times great epidemics devastated whole continents so frequently that the world's population barely held its own from century to century. In many instances whole tribes were wiped out. Such catastrophes are now almost unknown, although we still have with us the plagues of influenza, tuberculosis, syphilis, and pneumonia. Even these, however, are being conquered, so that their destructive influence is being stayed.
At the present rate at which the population of the world is increasing, the time is certainly not far distant when it will be necessary to utilize in the most economical manner possible every acre of soil capable of producing food. During the war the attention of agriculturists was very forcibly called to the enormous waste involved in our so-called animal industry. The first measure of food economy adopted in Germany at the beginning of the war was the slaughter of a large part of livestock. The same measure was adopted in Scandinavian countries and in all parts of central Europe. This was absolutely necessary, as Lusk and numerous other authorities have shown, for the reason that to produce one pound of water-free food in the form of beef or mutton requires the consumption more than 30 pounds of digestible food material. The cow is a much more economical means of food transformation, requiring the consumption of only a little more than 5 pounds of food for each pound produced, so that the waste of food in the production of milk is less than one-fifth as much as in the production of meat. This has led the food economists to recommend the reduced use of meat and the increased use of milk as a source of the complete protein required for sound nutrition. McCollum and other authorities, including representatives of the United States Department of Agriculture, have within the last four years persistently urged upon the public the importance of using more milk and less meat, and not simply as a matter of economy but as a matter of health as well, for it has been shown that the protein of milk is even superior to that of meat. It was found, indeed, that by the use of a few ounces of milk daily, a pint and a half, in connection with a dietary otherwise consisting wholly of foods derived from the vegetable kingdom, the body will be amply supplied with complete proteins, the milk not only furnishing protein of a superior character but serving also to supplement the proteins of the cereals, roots and other vegetable foods, supplying the amino-acids which they lack so as to render them also available for tissue growth and reconstruction.
This discovery respecting the important place which milk is capable of filling in the solution of the great and pressing problem of human nutrition is a highly important one, and its value has led to very active efforts on the part of the U. S. Department of Agriculture to enlarge the dairy interests and increase the milk production of the country as one of the best means of food economy which could be adopted. But even this is not a complete solution of the difficulty, for the keeping of milch cattle involves still a very large waste of food material, five pounds being consumed by the cow for each pound produced. The evident reason for this is the fact that the cow requires the large part of the foods she eats for her own use in maintaining heat production, supplying energy for exercise, supporting the work of the heart, lungs, digestive organs, etc. The food value of the milk produced represents simply what is left over after the cow has made use of what she needs for herself.
There can be no doubt that as meat production diminishes, as it is certain to do, milk production will likewise decrease. There is even at the present time a notable shortage of dairy products, and the average per capita production will undoubtedly continue to decrease for the same causes which inevitably lead to a lessened meat production. Some other source for the complete proteins needed to supplement the incomplete proteins of cereals and roots must be provided. Fortunately, Nature has supplied us with this all-essential foodstuff in that choicest of all our products, the nut. This is a vitally important fact which sometime will save the race from protein starvation.
A study of the relative protein content of nuts, milk, and meat shows that, pound for pound, the almond, beech nut and walnut contain on an average as much protein as does meat and five times as much as is found in milk, and protein which from rat feeding experiments appears to be of equal value. The chestnut, the chinquapin, the filbert, the hickory, pecan and pine nut contain on an average as much protein as is found in fish, while the butternut, the peanut and the pignolia contain twice as much or 50 per cent more than is found in the best of meat.
The following table shows the number of pints of milk equaled by one pound each of the several nuts mentioned, together with the calory value of the nuts per pound and of the amount of milk containing an equivalent amount of protein and the amount of each kind of nuts needed to supply supplementary proteins for one day:
| Pints of Milk containing as much protein as one pound | Calories Milk | Calories Nuts | Amt. needed for one day | |
|---|---|---|---|---|
| Acorn | 2.4 | 780 | 2620 | 8.3 |
| Almond | 6.1 | 2080 | 3030 | 3.2 |
| Beech nut | 6.6 | 2145 | 3075 | 3.0 |
| Butternut | 8.5 | 2762 | 3165 | 2.4 |
| Chestnut | 3.2 | 1040 | 1876 | 6.4 |
| Chinquapin | 3.8 | 1072 | 1800 | 6.4 |
| Filbert or Hazelnut | 5.0 | 1625 | 3290 | 4.0 |
| Hickory nut | 4.6 | 1495 | 3345 | 4.8 |
| Pecan | 3.6 | 1170 | 3455 | 5.6 |
| Peanut | 9.2 | 2090 | 2600 | 2.2 |
| Pinon | 4.4 | 1430 | 3205 | 4.8 |
| English walnut | 5.4 | 1555 | 3300 | 3.7 |
| Black walnut | 8.5 | 2762 | 3105 | 2.4 |
From animal feeding experiments it has been determined that about 20 oz. of milk will furnish sufficient complete protein to supplement a vegetable diet otherwise deficient in complete proteins. This amount of milk will supply one-third to one-half the total daily protein requirement for the average person. Nuts are so rich in these precious proteins, practically identical with those of milk, that the protein found in 20 ounces of milk may be furnished by 2 ounces of peanuts, 2½ ounces of butternuts, 3 ounces of almonds or beechnuts, 4 ounces of English walnuts, or filberts, 5 ounces of pinenuts (pinons) or hickory nuts, 5½ ounces of pecans, 6½ ounces of chestnuts or chinquapins, or half a pound of acorns.
The nut is one of the most important and interesting of all foodstuffs for the reason that it presents in concentrated form the most valuable and easily digestible of proteins. It is for this reason that the farmers of Northern Italy are able to thrive on a diet of which the chestnut is the staple. For the same reason 300,000 Pacific Coast Indians prospered for centuries on a diet consisting chiefly of acorns and pinenuts. In recent times, one of these Indians was known to be living at the age of nearly 140 years, and the farmers of the West and South before they had destroyed with axe and fire the splendid oak forests of pioneer days, depended chiefly on mast to fatten their hogs. The acorn was their chief source of protein, which is as necessary for a hog as for a college professor.