CHAPTER XVIII TOXIC SUBSTANCES OF EDIBLE FOODS-SOME IN COLLABORATION WITH A. L. BENEDICT, A.M., M.D., F.A.C.P. Medicinal and Toxic Substances of Edible Foods. Diseases Caused by Dietetic Errors and Various Food Poisons: Classi- In a work devoted to the scientific application of the fundamental doctrine of trophotherapy to the general principles of nutrition, there must obviously occur, here and there, an overlapping of pharmacology and toxicology on the one hand and of dietetics on the other-especially with regard to foods derived from the vegetable kingdom. Tannic acid and certain volatile and essential oils and pigments of more or less positive medicinal properties are found at least in some parts of all plants used as food or food adjuncts. MEDICINAL AND TOXIC SUBSTANCES OF EDIBLE FOODS The principal vegetable foodstuffs in which toxic or medicinal substances are found are as follows: Abies Nigra, or black spruce, possesses powerful antiscorbutic properties. The American Indians are said to have taught Jacques Cartier the use of this plant, which, according to Cartier, was at that time far superior to any antiscorbutic then known to European physicians. Aesculus hippocastanum, or horse chestnut, is a possible source of starch, when freed from the bitter medicinal principle. Acorns contain larger quantities of starch, which is available for breadmaking after the acorns have been buried underground for a certain period to extract the tannin. Asparagus contains an active principle, asparagin (C,H,N2O3), which is a stimulant diuretic and to some extent an arterial and nerve sedative. While contained mainly in the root, it is present to some extent in the stalk. The latter has been recommended as an oxytoxic and emmenagogue, as a nerve sedative and a diuretic in dropsy of various forms and as an aphrodisiac. Asparagin is an active principle, occurring in large rhombic crystals and found in many other plants, as in the shoots of asparagus, vetches, potatoes, licorice, the sweet almond, the root of the locust, etc. It is considered a derivative of succinic acid, and has diuretic properties, besides being a sedative to the circulation. It may be used in ascites, especially in children, in the anasarca of Bright's disease and in gout. It is eliminated in the urine as methyl mercaptan, which has a peculiar disgusting odor. It is excreted very rapidly, being noticeable from one to six hours after ingestion. There is no better test of gastric motility, absorption and renal elimination than the time of appearance and disappearance of the characteristic odor of asparagin. Bananas, when ripened and especially when cooked, develop a strong odor of amyl nitrite, and occasionally produce mild symptoms of vascular dilatation. Barberries contain a bitter yellowish alkaloid substance, berberin, which is also found in hydrastis and many other plants. Bitter almond, peach pits, cherry pits, etc., yield hydrocyanic acid from the inner action of the emulsin amygdalin. The latter is not present in sweet almonds. The therapeutic action of this acid is too well known to medical men to be repeated here. Chamomile, peppermint, catnip, sage, savory, saffron, boneset, and other herbs of this character are often used for making teas. They do not exert any very powerful medicinal action nor have they any nutritive value. They do, however, exert a slight medicinal action in that they are sudorific and more or less sedative to the nervous system. Coca erythroxylum is the plant from which the alkaloid cocain is derived. It is entirely distinct from caffein. The general use of the plant is as a nerve sedative and stimulant. It is incorporated with a popular drink which is now used as a beverage. Crataegus is a species of thorn apple occasionally eaten as a fruit. Aside from the astringent and volatile principles contained in the apple, exaggerated claims have been made by certain practitioners for an extract or tincture made from this apple, which is alleged to be valuable as a heart tonic. Carrots, parsnips, celery, anise, caraway, dill, coriander and parsley, like all other umbellifera, contain volatile oils which are poisonous in sufficient doses. When the foliage of carrots is wet, it gives off a poisonous substance, perhaps an essential oil, which exerts an irritating action upon the skin similar to eczema or to the irritation produced from the poison ivy. Parsnips are considered poisonous if used the second year. The bleaching of celery by burying in soil, it is claimed, frees the stalks and leaves of their volatile oil. Cucumbers, squashes and pumpkins belong to a family pervaded with a bitter, cathartic principle which may occasion gastric distress and diarrhea, when an unusual quantity of this principle is present. This occurs especially if the fruit is over-ripened or a faint fermentative process has begun. Coffee, tea and cocoa were discussed in the previous chapter on beverages and stimulants and are more or less commonly used as food adjuvants. They contain definite physiological principles, purins, diand tri-methyl xanthin, including tannic acid, which is injurious to health. Red cabbage contains litmus, so also do many of the pigments of fruits, i.e., such vegetables as the beet, the stem of the red apple, etc. While of no known therapeutic or toxic importance, these color reactions may interfere with the examination of stomach contents, and may lead to a false diagnosis of blood, bile and other colored abnormal ingredients of the feces. Corn, as we learned in Volume I, Chapter XIII, is indigenous to America. Of late years it has been accused of being the cause of pellagra, probably unjustly, unless as a factor in improperly balanced diet. (See Rye.) Elderberries, obtained from the elder bush, Sambucus nigra, are often used in the same way as huckleberries. They have an active principle, but in very small quantities. These berries are used to adulterate huckleberries and in the making of elderberry wine. Grapes, while a delightful fruit, are rich in tartaric acid. The skins contain quantities of tannin. Horseradish, watercress, mustard, turnip, radish, all contain aromatic sulphur compounds which in large quantities are more or less irritating to the alimentary canal. Hops, in addition to a small quantity of asparagin, contain also a liquid alkaloid, lupulin and lupulinic acid (C40H82019), both of which were mentioned on page 561, when describing the process of brewing. Hops are mildly hypnotic and sedative, and are sometimes used as an anaphrodisiac. A candy in the shops, sold under the name of Iceland moss, is usually flavored with anise. Besides its use as a nutrient, Iceland moss is of value as a demulcent. It is also considered hemostatic and expectorant. Lettuce contains a small amount of hyoscyamin (C17H23NO1) and other active principles. These principles have been referred to by some writers as a mild form of opium. Licorice is obtained from the root of the glycyrrhiza, a native of Europe and largely cultivated in many other parts. It is slightly demul cent and mildly laxative. Licorice has an agreeable taste and increases the flow of saliva when slowly chewed or sucked. It contains a small amount of sugar, also asparagin and is used as an expectorant. It is much employed in acute bronchitis. Limes, lemons, oranges, grapefruit, etc., contain antiseptic oils in the skins, while the fruit contains considerable quantities of citric and malic acids. Manna is a saccharine substance containing various sugars. It is derived from a species of ash tree, oak, larch, flowering ash and the Indian Alhagi plant. It is a legume and possesses laxative as well as nutritive qualities. Manna contains mannotebrose (C24H42021), each molecule of which is said to contain two molecules of galactose, one molecule of dextrose and one of levulose. Mushrooms are described in Volume I, Chapter XIII, page 449, and their danger pointed out. Some varieties of this form of fungi contain several active poisonous substances, of which muscarin (C,H,NO2+H2O) is the chief. Amanitin is found in one variety, while phallin is found in others. Cooks have various tests for detecting these poisons. For instance, if a silver spoon or fork is used to turn the fungi while cooking, the metal will be unaffected by edible fungi; but the acrid juice of poisonous mushrooms will corrode or blacken the silver. None of these tests taken singly is reliable. Onions and garlic contain allyl sulphid, which is expectorant, antiseptic and somewhat irritating. This active principle may produce intense gastro-enteric irritation if taken in large quantities or in persons having a peculiar idiosyncrasy. Regularly taken in moderate quantities, these vegetables seem to be fairly efficient prophylactics in tuberculosis. Oats belong to the cereal grasses, which constitute the principal fodder of stock animals, while the seeds are a most important food for man. Wood states that the whole family contains but one poisonous or even suspicious genus, lolium. Oats are an aphrodisiac to horses, due to the active principle, avenin, which they contain. This active principle is slightly toxic to man, if the use is long continued. Buckwheat, while not a true cereal, contains an active principle which is liable to produce indigestion and skin eruptions. Pomegranate, as a fruit, was described on page 495. The rind contains the same liquid alkaloid, polletierin (CH13NO), as the bark of the root and therefore has powerful anthelmintic properties. Pumpkin seeds are obtained from the pumpkin fruit which is described on page 514, and are useful as an anthelmintic in the treatment of tapeworm. They may also be used as a food. Potatoes, tomatoes and egg plant all contain mydriatic alkaloids, but not to any appreciable degree in their edible portions. Occasionally, however, the green parts, even raw potato peelings, may produce mild. poisoning. Potato tubers, if young or diseased, are liable to contain an alkaloid solanidin (C26H41NO2), a glucoside-like combination with sugar, though this particular alkaloid is usually in negligible quantity. Severe, though not fatal, wholesale poisoning from mydriatic alkaloids has been recorded. May apple belongs to the same genus as the officinal Podophyllum. This apple is occasionally eaten and if liberally ingested, more particularly if eaten green, may produce violent catharsis. Persimmons, as fruit, have been described on page 483. They are palatable and wholesome after frost, but prior to being "frostbitten" they are disgustingly bitter, astringent, and exert a cathartic action. Pennyroyal, lavender, sage, hoarhound, thyme, spearmint, peppermint, rosemary, catnip, occasionally employed for flavoring, belong to the mint family. All of them possess a volatile oil more or less medicinal, but not toxic unless in large quantities. Pawpaw and pineapple, as fruits, are considered in Volume I, Chapter XV, page 490, and are said to contain digestive ferments similar to trypsin and amylopsin, acting in alkaline or neutral media, as do also the insectivorous plants not used as food. These ferments are not so sensitive to temperature as animal ferments, but are destroyed by boiling. Rye and corn are subject to smut just before ripening. From the former the fluid extract of ergot is obtained and from the latter ustilago maydis is produced. They are parasitic plants and not themselves used as food, but frequently contaminate the cereals. Rhubarb, described in Volume I, Chapter XIII, page 435, is a valuable article of diet. Its use as a food or beverage is contra-indicated in per |