Speaking generally, by the title “carbohydrates” is principally meant vegetable food, in the same way that by “albuminous” animal food is mainly designated. Still there are vegetables which contain more albumin in their natural watery condition than meat; thus peas contain 23 per cent. of albumin, whereas lean beef has barely 21 per cent., and fat beef only 17 per cent. But one thing must especially be considered, and that is the fact that a considerable portion of peas (about 28 per cent.) is not absorbed, as Rubner has shown, whereas nearly the whole albumin contents of lean beef is.

Most albumin is found in leguminous vegetables, such as peas, beans, and lentils; and these are also rich in carbohydrates, as will be seen from the following table of percentages by Rubner, in which reference is also made to the nutritive value of our most important fresh vegetable foods:—

From the above we see that peas, beans, and lentils have the most nutritive properties, for they contain not only much albumin but also much carbohydrates, and also more fat (except in the case of ground Indian corn and rye), than the other above-mentioned vegetables.

Thus we shall not be surprised to learn that we can thrive very well for a long time by using such exclusively for food, as has been proved by the experiments of Rubner and Woroschiloff. The drawback to this kind of food is that it requires the stomach and intestinal juices to perform much more work, for reasons already mentioned; and, in consequence, less of it is utilized; and, after a certain time, the development of stomach and intestinal troubles is facilitated.

Another drawback attending vegetables is that they contain purin bodies and form uric acid, indeed in considerable quantities, especially peas and beans, as Walker Hall^[266] discovered from experiments conducted in the Caroline Institution at Stockholm. Of the various kinds of cereal foods rice forms the least uric acid, and also, as already mentioned, contains the least salt, for both of which reasons it is the best food for the kidneys. It is, at the same time, a very valuable nutritive food, as it contains a very large quantity of carbohydrates, viz.: 77.6 per cent., and almost the least cellulose of all foodstuffs, as shown in the table above; but it is very poor in fat, and has also but a small amount of albumin. As it contains so little proteid and fat its adoption by people with vegetarian proclivities necessitates the simultaneous use of leguminous vegetables and of fats. It has the advantage over leguminous vegetables in that its starch components are extremely digestible. Thus it is the most valuable vegetable food, in spite of its being poor in mineral matters.

Granted the enormous value of rice as a foodstuff, we must express our surprise that it enters in so small a degree into our daily diet. In Europe, and in other parts of the world where persons of European descent reside, as also in America, the potato takes the same place as rice does in Asiatic countries, though the former is much less rich in nutritive qualities, as we will show later on.

Rice must be a most excellent food, for the natives of Asiatic countries, who live almost exclusively on this, offer us examples of great tenacity, and of resistance against bodily fatigue. Take the Japanese for example. Their coolies, as shown already, are able to do enormous muscular work on rice and fish food, and in athletics, such as jiujitsiu, they present a great example of muscular strength, though it cannot be denied that it is more their dexterity and knack than their superiority in mere strength that leads them to victory. That by means of rice diet, as by carbohydrates, great muscular energy can be obtained, is a well-known physiological fact.

The starchy portion is converted, through the digestive ferments in the saliva, pancreatic, and intestinal juices, into dextrin and grape sugar; absorbed through the intestines, it is deposited in the form of glycogen in the liver, the muscles also absorbing a large part of this glycogen. Through work this glycogen is exhausted. Thus work is performed mainly at the expense of the carbohydrates, which are the prime generators of muscular energy. We have also seen that the above-mentioned Japanese coolies perform their incredible muscular efforts largely on such food only. Still, a part of the muscular energy of the body can also be provided by the proteids and fats.

Carbohydrate foods, and especially those that are poor in fatty contents, such as rice, and especially potatoes, which are the most deficient of all (having but 0.1 per cent. of fat), necessitate the simultaneous use also of fat; for this kind of exclusively carbohydrate diet would invariably lead to starvation unless there was a plentiful supply of fat with it; and the best and most agreeable form to introduce fat into the body is by means of butter.

Butter is very nutritious, as it contains, according to Rubner, 83.1 per cent. of fat, 0.9 per cent. of albumin, and 0.5 per cent. of carbohydrates. One hundred grammes of butter contain, according to Rubner, 779 calories. In addition to the above, butter also contains salts, and from 8 to 12 per cent. of water. A diet rich in carbohydrates could not be well assimilated without butter; but, at the same time, the abundant use of the latter also necessitates the use of carbohydrates, which are the best vehicle for butter; therefore, when in diabetes we prescribe much butter or other fats, we make it a rule, also, to give some kind of food that contains some amount of carbohydrates, such as brown bread or green vegetables, or sometimes, in mild cases, also boiled potatoes.

Potatoes, when new and watery, contain 16 per cent. of carbohydrates; when they are old, 22 per cent. In many European countries they form a most important article of diet. Though, as shown in the foregoing table, they contain only 2 per cent. of proteids, they contain also important salts, such as a certain amount of citric acid and citrates of potassium, sodium, and lime. Thus potatoes, by means of these salts, are also an alkaline food, and if consumed in very large quantities, the acidity of the urine can become much diminished. These salts are burned in the body, and the potassium is then transformed into a carbonate salt. Mossé recommends potatoes in large quantities as a preventive of diabetes.

Thus, after food which is rich in such vegetables as potatoes, or after fruit with much fruit acids, the urine can become less acid; but after food that abounds in proteids the urine becomes acid. This happens after eating much meat, or leguminous vegetables rich in proteids. Such a very acid urine is often passed by diabetics; therefore in their diet a certain amount of fruits, rich in salts but poor in sugar, may give good results.

The most rational diet is that which combines all the principal items of nourishment—in the greatest proportion proteids, as from such the body is built up and waste tissues replaced; next in proportion carbohydrates, from which, as already shown, we obtain muscular energy; and to a smaller extent than the two preceding must be taken fat, which serves to produce heat in the body. Besides these three important constituents there is a further class of valuable substances indispensable for our well-being, and these are the mineral matters. From experiments made by Lunin^[267] in Bunge’s laboratory, and by Förster,^[268] it has been shown that animals cannot live if fed on food that is devoid of mineral matters; and the latter savant has further shown that animals can live longer without any food at all than with food that has no salt whatever. We need these salts for different purposes, such as building up the skeleton; and the condition of the teeth depends also on the richness of our bodies in lime, and in order to obtain this it is indispensable to introduce food that contains a maximum of it. This is of special importance in the nutrition of children.

We give below a table by Bunge showing the amount of lime contained in many of our common articles of diet; 100 grammes of dried substance yields milligrammes of lime:—

Probably no cell growth can take place without lime, and even if grown animals are fed on a diet containing no lime they soon become weak and will certainly die at some time from it; therefore not only children, but adults also, must obtain a sufficient quantity of this, and milk or water that contains lime is certainly the best means by which to get it. Very interesting are the observations of Roese,^[269] showing that in parts of Germany where water poor in lime is drunk less people are fit for military service and the teeth of the population generally are in bad condition. Lime is indispensable for our body, for it has a favorable influence upon the work of the heart, the secretion of stomach juice, and the movements of the intestines; it increases the quantity of the urine; and, as Lehmann, Posner, and v. Noorden have shown, the carbonate of lime dissolves uric acid.

Another most important mineral salt is iron, this being an essential element of the hæmoglobin of the blood. This latter is the red coloring matter of the blood, and consists of the combination of an albuminous body-globulin with a ferruginous body, the hæmatin. According to Bunge,^[270] a man weighing 70 kilos has in his blood 3.2 grains of iron, and according to Schmidt from 2.4 to 2.7 grains.

Bunge maintains that organic iron is more readily absorbed than inorganic iron, and that the best way to obtain sufficient iron in the body will be to choose a food that is rich in iron

We present below a table by Bunge, showing the various articles of food that contain the greatest percentage of iron; 100 grammes dried substance contain milligrammes of iron:—

We thus see that certain kinds of fruits and vegetables are noticeably very rich, not only in lime, but also in iron; such are strawberries, Malaga or California grapes, peas, potatoes, etc.

If not rich in lime, yet, on the other hand, rich in iron, are certain vegetables and fruits, such as spinach, asparagus, the outer leaves of cabbages, lentils, almonds, apples, cherries, etc.

As it is very probable that organic iron is more easily assimilated than inorganic, it would be advisable in those cases which require a better nutrition of the blood and an increase of its contents in iron, to give plentifully the above-named vegetables and fruits.

The fruits mentioned as being rich in iron, such as apples and cherries, or in iron and lime, such as strawberries and grapes, can not only increase the amount of iron in the blood, but increase its alkalinity; and at any rate if they cannot increase it they can at least preserve it; and not in the blood only, but also in the other fluids of the body, this being effected through the acids contained in such vegetables, such as citric, tartaric, malic, acetic, and oxalic acids, which are either in a free state or in combination with alkalies, as alkaline salts. After the combustion of the acids in the body they appear as carbonates, thus increasing the alkalinity of the blood and other fluids.

Of the above acids, grape-fruit contains mostly citric acid, as also do oranges, lemons, gooseberries, etc.; apples and peas contain malic acid, and grape juice, tartaric acid.

There can be no doubt that the above-named fruits and vegetables—and let us not omit the important potato—are able to do us good service in the prevention and treatment of the condition of acid intoxication that we find in severe forms of diabetes or in serious disorders of the liver; but also in uric acid diathesis they can render valuable assistance.

For a long time past through various kinds of fruit, especially berries, various cases of gout have been successfully treated. Strawberries, cherries, and apples especially have been recommended in such conditions, and the value of such a prescription has been confirmed by the experiments of J. Weiss,^[271] made in Bunge’s laboratory. We also used grapes in large quantities, besides the above-named fruits.

In case of gravel, also, where the concrements consist of uric acid, the administering of such fruit can give beneficial results.

Besides mineral salts and vegetable acids, fruits and vegetables contain a third important substance, which is cellulose, the framework of their cell tissues. Although this is very difficult to digest, still there can be no doubt, from the experiments made on animals and also on man by Weiske,^[272] that cellulose is also a nourishing food, for he proved on himself and another person that from 46 per cent. to 65 per cent. of the cellulose can be digested.

The chief advantage, however, of cellulose does not lie in its nourishing properties, which are not great, but in the fact that it acts as the best natural stimulus to the peristaltic movements of the intestines. Thus food that contains such a residue (which is contained most largely in vegetables and fruit) is also the best to use if we desire to keep the intestines open and to observe the most important precept of their hygiene. This hygienic condition can also be much advanced by vegetables of the cereal kind, which, as shown in the chapter on hygiene of the intestines, may act as a disinfectant of the same through the milk acid that is formed therefrom in the intestines.

Vegetables and fruit have thus very great advantages, and even in winter our daily diet should consist plentifully of them, as grape-fruit, oranges, etc., can be obtained at that time of the year. But when vegetables and fruit are exclusively used as a diet they present certain dangers, as we point out in the next chapter on the advantages and disadvantages of a vegetarian diet.