This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
The tomato is a vegetable which was introduced into this country about sixty years ago, the value of which is becoming more and more appreciated. In Germany it is still sold as a fruit of luxury rather than as a common vegetable. It is wholesome when eaten raw as a salad with vinegar and oil, and it forms a popular ingredient of strong condiments, such as tomato catsup. It is refreshing, slightly acid, and easily digested. The oxalic acid which it contains makes it injurious in cases of gout or the uric-acid diathesis. The tomato is much prized as a canned vegetable on account of the fact that it retains more of its original flavour than do most vegetables preserved by this process.
The eggplant is related to the tomato, and like it contains many seeds when full grown, but it is much less digestible, especially when fried, and is not a suitable food for invalids.
Cucumbers are mainly eaten raw, and they should be young. Like celery, they contain too much woody fibre to be consumed in bulk. They are valuable for pickling in vinegar or in the making of chowchow, but they are always indigestible; this is due in great part to the large size of the seeds which the vegetable contains, and it should never be eaten by any one excepting those having vigorous stomachs. Eaten raw, even in small quantities, it may produce violent colic and diarrhoea.
Asparagus is a vegetable possessing a very delicate flavour, and from the fact that it is among the first of the fresh vegetables to appear in the early spring it is highly esteemed. When young and tender it is very digestible, even for invalids. The green asparagus contains more bitter and resinous principles than the white. It has been claimed that it possesses some influence as a cardiac sedative as well as aphrodisiac action, but these properties are imaginary. It is, however, slightly diuretic, and it owes this influence to a substance called asparagin, which may be obtained in crystalline form. Asparagus imparts a very strong and disagreeable odour to the urine which I have known to appear within an hour after it has been eaten, and which persists from twelve to twenty hours. It is caused by a volatile sulphur product, a methyl mercaptan, which has been proved to originate in the intestine during digestion, from whence it is absorbed.
Rhubarb, or "pieplant," the stems of the leaves of which are eaten stewed, is an excellent vegetable. The flavour is quite tart, and the fibre is stringy, but thorough cooking renders it soft and digestible. It is laxative, and is therefore useful in cases of chronic constipation. This wholesome vegetable has not received the attention it deserves. In Germany, for instance, it is still grown merely as an ornamental garden plant on account of its large showy leaves. It produces calcium oxalate in the urine if eaten in excess, and must therefore be avoided in oxaluria, gout, and rheumatism.
Pumpkins and squash contain much water and a good deal of coarse fibre. Tender and young summer squash is fairly digestible, but presents no special dietetic advantages. The pumpkin is one of the oldest vegetables on this continent, for it was grown extensively together with maize by the early Indian tribes.
Onions, garlic, shallots, and leeks, which are edible both as fresh vegetables, and after long keeping, are useful as condiments for flavouring salads, meat stews, and other foods. They are also eaten independently for their nutritive properties, which are somewhat greater than those of the four or five vegetables last considered. Tender young leeks and white onions boiled and served with milk or cream are very wholesome and of delicate flavour. They possess, in common with the other green vegetables, a moderate laxative action, and are antiscorbutic. They impart a strong typical odour to the breath, which appears within two or three hours, and if constipation exists, persists for twenty-four hours or more. This is due to volatile substances which are absorbed by the blood from the alimentary canal and carried to the lungs, where they are liberated.
Vegetable marrow is a highly succulent vegetable, somewhat resembling the pumpkin. It possesses an agreeable flavour, but consists so largely of water that it is of scarcely any use as food.
Cranberries are really more of a fruit than a vegetable, but they are usually eaten with meat as a vegetable. They are serviceable for their agreeable acidity and flavour, but unless very thoroughly cooked and made into a jelly with much sugar, they are indigestible, for their outer coatings are extremely tough. They should never be given to invalids.
The composition of some common vegetables is thus tabulated by Moss:
Composition of Vegetables
Sugar and gummy matter
• • ■
Other organic matter
The following analyses of common vegetables have been made by König:
Other non-nitrogenous extractives
Other non-nitrogenous extractives
The two preceding tables differ slightly in detail, but no more than the average variation in percentage composition of the vegetables when not grown under identical conditions. They agree as nearly as can be expected.