I am citing my experience with the peanut not for the purpose of recommending this product, for I am obliged to confess that I was soon compelled to abandon the use of peanut butter prepared from roasted nuts, for the reason that the process of roasting renders the nut indigestible to such a degree that it was not adapted to the use of invalids, but simply as an illustration of the readiness with which the public accepts a new dietetic idea when it happens to strike the popular fancy. Ways must be found to render the use of nuts practical by adapting them to our culinary and dietetic customs and to overcome the popular objections to their use by a widespread and efficient campaign of education.
Attention has already been called to the superior nutritive value of the nut. It has other excellencies well worthy of consideration; for example, the protein of nuts is of the very choicest character. Recent investigations by Rubner, Osborne, Mendel, and others have shown that every plant produces its own special varieties of proteins. There is indeed a wide difference even between the proteins of various cereals and the proteins of many vegetables differ so widely in character from those of the human body that it is doubtful whether to any extent they can be utilized for human nutrition. Fortunately the potato is in this regard an exception and furnishes a very excellent type of protein. This objection does not apply to nuts. The proteins of nuts are in fact so very closely allied to those of the animal body that food chemists of a generation ago referred to the protein of nuts as vegetable casein because of its exceedingly close resemblance to the protein of milk.
The fats of nuts, their leading food principle, are the most digestible of all forms of fat. Having a high melting point, they are far more digestible than animal fats of any sort. The indigestibility of beef and mutton fat has long been recognized. The fat of nuts much more closely resembles human fat than do fats of the sort mentioned. The importance of this will be appreciated when attention is called to the fact that fats entering the body do not undergo the transformation changes which take place in other foodstuffs; for example, protein in the process of digestion is broken into its ultimate molecular units. Starch is transformed into sugar, which serves as fuel to the body, but fats are so slightly modified in the process of digestion and absorption that after reaching the blood and the tissues they are reconstructed into the original form in which they are eaten; that is, beef fat is deposited in the tissues as beef fat without undergoing any chemical change whatever; mutton fat is deposited as mutton fat; lard as pig fat, etc. When the body makes its own fat from starch and sugar, the natural source of this tissue element, the product formed is _sui generis_ and must be better adapted to the body uses than the animal fat which was _sui generis_ to a pig, a sheep, or a goat. It is certainly a pleasant thought that one who rounds out his figure with the luscious fatness of nuts may felicitate himself upon the fact that his tissues are participating in the sweetness of the nut rather than the relics of the sty and the shambles. It is true that nuts are poor in carbohydrates; that is, they contain no starch and little sugar, but this deficiency can be easily supplied by fruits, as will be readily seen by reference to Table V.