Fruits consist chiefly of water, and for this reason are scarcely ever looked upon as nutrients. They contain a small amount of nitrogenous elements and agreeable acids, which are very useful in keeping the vital machinery in good working order. That they contain more nutriment than is generally supposed is proved by the fact that the natives of some countries live almost wholly upon fruit. The Arab, as well as his camel, lives principally upon dates. In some countries the inhabitants live almost exclusively upon bananas. Undoubtedly fruit was the principal article of food eaten by Adam and Eve while they remained in the Garden of Eden.
The large amount of water that fruits contain makes them an excellent article of food for summer, when the system requires more liquid, especially in dry countries where the water supply is scarce or impure. The water of fruits is absolutely pure, having been distilled by heaven's own process, and then canned and sealed by a skin that is impervious to germs. There is no danger of contamination from drinking it, as long as the skin is not punctured in any way. The juices of the watermelon, orange, lemon, and lime are among the best for drinking, and can be taken at any time, as they contain no nutriment excepting a little sugar; but the juice only should be taken, as the pulp, or cellulose, of fruit is indigestible.
Another very important element of fruits is their acids, which are valuable on account of their influence upon certain functions of the body; for example, upon the kidneys, acting as a natural diuretic; and also as a natural laxative, though not having the same effect as a laxative medicine, for fruit only produces a natural condition, and if the system is already in a natural condition, it has no effect. Perhaps the most important point in the use of fruits is the effect their acids have upon germs. It has been proved by repeated experiments and analysis that germs will not grow in fruit juice; therefore, the juices of fruits are natural disinfectants.
This does not apply to the juice of the lemon, lime, and orange alone, but the acids of all fruits are disinfectants to a certain extent, some more than others. The juice of one lemon in two glasses of water, if left standing fifteen or twenty minutes, will thoroughly disinfect it. Thus fruit can be of great assistance to travelers, as the water on cars and in waiting-rooms is often so impure that it would be dangerous to partake of it.
Three different kinds of acids are found in fruits: citric acid, malic acid, and tartaric acid. Citric acid is found in lemons, limes, grapes, and oranges; and malic acid is found in almost all acid fruits, but more abundantly in apples, cherries, plums, and pears. Tartaric acid is found in considerable quantities in the grape, and is present in small quantities in other fruits. In canned grapes, it is often found condensed in small chunks in the bottom of the can. In pie-plant, there is a poisonous acid called oxalic acid; for this reason pie-plant is unsafe to use; people have been made seriously ill by eating its leaves for greens. A very small per cent. ' of oxalic acid is also found in the tomato; for this reason it is not so good a food as some fruits, although it contains such a small amount that it is not usually felt.
The acids of fruits are digestible; that is, they change when entering the system, so that they do not have the effect that common acids do. Another element of fruits is the sugar which they contain. Some fruits contain a great deal more than others. Figs, dates, and raisins contain the most; but grapes, cherries, currants, and apples contain quite a percentage, although the acid hides it from the taste in some of the fruits, as is the case in the cherry and currant. Some fruits, as the plum, apricot, and peach, contain very little sugar.
The sugar which is found in fruits is the sweetest of all sugars, and in its natural state, when eaten with the fruit, is easy of digestion, being just what the system requires. Honey, which is nothing but the sugar of fruits, because it is taken from the blossoms, would be a much better and sweeter sugar than cane-sugar, if it were not adulterated. Sometimes bee keepers feed their bees upon a cheap grade of molasses, poor sugar, etc.; and sometimes when the blossoms of wholesome plants and trees are scarce, bees will gather honey from the flowers of weeds, or tobacco plants, and even collect the honey dew from oak leaves, which is only a secretion of an insect. If the pure honey from flowers could be obtained, it would be better than cane-sugar; but even then it would contain some of the pollen of the flowers and some germs.
There is another constituent of fruits, which, although it does not add to the nutritive value, holds the juices and determines the shape of the fruit, and that is the cellulose or woody fiber. In some fruits, this is very thin and easily broken up, as in the strawberry, but in others, it is quite tough, woody, and indigestible, as in the orange. It is better to reject the cellulose of such fruits. For sick people and those having weak stomachs, fruit juice is best, and can often be eaten where the fruit can not.
The use of fruit for curing disease is by no means a new idea. Pliny, the Roman naturalist, who perished in the eruption that destroyed Pompeii, mentions the grape-cure in his day. At the present time, the grape-cure is used quite extensively in France, Switzerland, and Germany, and has been tried to some extent in California. But curative properties are not peculiar to the grape alone, as there are the strawberry-cure, the peach-cure, the cherry-cure, and the apple-cure.
The reasons why fruit is so beneficial in cases of disease, are as follows : First, because they are disinfectants, clearing out the germs from the stomach and alimentary canal; second, they break up the waste substances so they can be eliminated by the kidneys.
Fruits are of great value in the treatment of fevers, sick headache, nervous headache, biliousness, Bright's disease, obesity, consumption, and intestinal disorders. Fruits are eaten with greater benefit, if eaten alone. If other foods are eaten at the same meal, great care should be taken in the combination. Fruit and vegetables do not combine well; fruits and eggs do not unless the eggs are raw; neither do very acid fruits combine well with grains, as the acids, if in too great a quantity, hinder the digestion of starch.
Fruits contain an abundance of water, a meager supply of albumen, sugar, acid, and cellulose; but no fats, except in the olive, and only a very small amount of starch, except in the green fruit. But fats, while nearly absent in fruits, are just what nuts can supply. In cold climates especially, the fats are very essential for producing heat in the body. The system can get along better without starch than fats. Nuts and fruits therefore make an ideal diet.