AND THEIR PREPARATION

We are now to furnish for the body the third great food principle, the carbohydrates. These we mean when we speak of the starches and sugars, and with unimportant exceptions, they are furnished by the vegetable world only.

As we have seen, that troublesome body, cellulose, plays here a large role. It is the skeleton, so to speak, of plants, built by them out of sugar and starch; the chemist finds no diffi- culty in his laboratory in turning it back into dextrin and sugar, and our stomachs too can digest a large part of the cellulose of very young and tender plants, — from 47$ to 62$ it has been found, of young lettuce, celery, cabbage and carrots, — but in older plants, the cellulose proper becomes all intergrown and encrusted with substances of a woody and mineral nature, from which even the chemist separates it with the greatest difficulty, while our digestive juices are entirely un- equal to the task. Therefore it is that the whole art of the cook is needed in treating this substance; she must soften it, she must break it up, and in many cases separate it as completely as possible from the sugars, starches and proteids which it hinders us from appropriating to our use.

fa Cellulose.

In some cases, as in oatmeal and gra- ham flour, we leave the cellulose because of its mechanical action on the bowels. To be sure, this is a wasteful process, for the cellulose carries with it when it leaves the body considerable undigested food, but better this waste than to give the muscles of our intestines so little work to do that they be- come unable to digest any but fine, condensed foods.

As a rule, however, we must think of cellulose not as a food at all, but as a tough, foreign body which we must reckon with before we can utilize the proteid and starch particles of many important vege- table foods.

Amount of The carbohydrates, especially the

Carbohydrate, starches, are the cheapest of the food constituents and therefore most apt to be in excess, especially in the food of the poor. According to estimates already given, an adult at average hard work gets along nicely with \\ Ibs. of carbohydrate mate- rial (meaning, of course, the dry amount of this one principle), though fortunately, as mentioned under "Fats," it is found that some of this large amount can be exchanged for fat, if the body, for any reason can better use the latter. Brainworkers and the richer classes the world over take less of carbohy- drates, at least in their starch form, and more pro- teids and fats.

Inasmuch as we get these carbohydrates from the vegetable kingdom, and because the housewife must furnish them combined with other principles as in bread and other things made of flour, and in various dishes in which vegetables are combined with meat,

Digestibility of Vegetable Foods. 77

milk, eggs, etc., we will cease speaking of carbohy- drates as such, and will give a few hints as to how to prepare vegetable foods so that we can get the most out of them, bearing in mind, however, what has been said about not following out this principle to the ex- tent of weakening the bowels.

TO what extent This leads us, first, to examine the digested. general digestibility of the whole class of vegetable foods; meaning by this, not the rapid- ity nor the ease, but the extent to which the nutritive principle is yielded up to us. It has been found that, as usually prepared, vegetable foods give up to us from i to -J less of their nutrients than do animal foods, and especially is this true of those that are rich in proteids. To illustrate: a workman eats as part of his dinner a dish of boiled beans, but though he rightly considers that he has been eating a nourishing dish, he has really absorbed only 60$ of the nitrogen- ous substances contained in it, the other 40$ passing from him unused because of its intimate connection with the cellulose; at least this was the case with Prof. Strumpell who records the result of personal experiments on the digestibility of beans cooked whole. Now this workman digested of the meat part of his dinner 97-|$x and this comparison shows how the tougher kinds of cellulose interfere with the absorp- tion of the food matters which they enclose.

The starch part of vegetable food we seem to get out much better than the proteid part, even with our ordinary methods of cooking; thus out of cooked rice we get almost 99$ of the starch, but only 80$ of what proteid it contains; flour in the form of noodles

78 The Shady Side of Vegetable Diet.

and macaroni yields up 98|$ of its starcli and 80$ of its albumen, — in the form of bread a little less of each. The potato will give us only 75$ of what little pro- teid it contains, but as high as 92.5$ of its starch. Effect of too Although the starch-containing foods much starch are cheap and although they yield up a good per cent of this nutritive princi- ple, they must not be used to excess for the following reason. Starch must first be turned into sugar by our digestive juices before it can be taken up into the blood, and if the stomach is given more at a time than it can master, certain fermentations may take place, and digestion be influenced. The best author- ities say that without doubt the continued and severe diarrheas of small children are due to the fermenta- tion of starch foods for which their digestive organs are not yet ready.

These fermentations, the irritating action on the bowels of too much cellulose, and the loss of a good deal of proteid substance connected with it form the shady side of a vegetable diet. Even the ox with his many stomachs gets out of grass and unchopped hay only 60$ of the proteid and 50$ of the fat contained in it.