This section is from the book "Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc.", by George Francis Atkinson. Also available from Amazon: Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc..
Calories For One Cent.
Flour (roller process) .......
Coprinus comatus . .
Pleurotus ostreatus . .
Morchella esculenta . .
Agaricus campestris . .
The mushrooms have been valued at 25 cents per pound, which is probably considerably below the average market price for a good article. It should also be remarked that the amounts given in this table are the digestible and hence available constituents of the foods. The only exception to this is in the case of the fats and carbohydrates of the mushrooms, no digestion experiments having been reported on these constituents. In the absence of data we have assumed that they were entirely digested.
The beef and beans are typical animal and vegetable foods of the proteid class. A glance at the table will show how markedly they differ from the mushrooms. The latter are nearest the cabbage in composition and nutritive value. The similarity between the cabbage and the Agaricus campestris here analyzed is very striking. The potato is somewhat poorer in fat, but very much richer than the mushroom in carbohydrates.
The figures in the last column will vary of course with fluctuations in the market price, but such variation will not interfere at any time with the demonstration that purchased mushrooms are not a poor man's food. Here we find that one cent invested in cabbage at 11/2 cents per pound, gives 93 calories of nutrition, while the same amount invested in Agaricus campestris - the common mushroom of our markets - would give but 5.3 calories, although they are almost identical so far as nutritive value is concerned.
The same sum invested in wheat flour, with its high carbohydrate and good proteid content, would yield 658 calories or one-sixth the amount necessary to sustain a man at work for one day. The amount of mushrooms necessary for the same result is a matter of simple computation.
Mushrooms, however, have a distinct and very great value as a food of the third class, that is, as condiments or food accessories, and their value as such is beyond the computation of the chemist or the physiologist, and doubtless varies with different individuals. They are among the most appetizing of table delicacies and add greatly to the palatability of many foods when cooked with them. It is surely as unfair to decry the mushroom on account of its low nutritive value, as it is wrong to attribute to it qualities which are nothing short of absurd in view of its composition. In some respects its place as a food is not unlike that of the oyster, celery, berries, and other delicacies. Worked out on the basis of nutritive value alone they would all be condemned; the oyster for instance presents a showing but little better than the mushroom, and vastly inferior, so far as economy is concerned, to the common potato. This, too, for oysters purchased by the quart. The nutritive value of one cent's worth of oysters "on the half shell" would be interesting!
The question of the toxicology of the higher fungi is one of very great theoretical and practical interest. But on account of the great difficulties in the way of such investigations comparatively little has yet been accomplished. A few toxic compounds belonging chiefly to the class termed alkaloids have, however, been definitely isolated.