Any consideration of the question of antiscorbutic foodstuffs brings into sharp relief the difference between empiricism and scientific investigation. For well over a hundred years it was generally known that scurvy could be cured by fruits or vegetables, and yet no further progress was made toward a more complete understanding of the value of these foodstuffs. As far back as 1847 Budd ascribed the action of antiscorbutic foods “to an essential element, which, it is hardly too sanguine to state, will be discovered by organic chemistry or the experiments of physiologists in a not far distant future.” Busk, in giving his testimony in 1877 before the British Scurvy Commission, said that it was his belief “that scurvy was due to the fact that the diet was lacking in a peculiar and as yet little-understood factor.” The question remained in this hypothetical and inactive state until it was attacked recently by experimental methods. Decided advance has been made only in the past few years, since these foodstuffs have been studied from a quantitative viewpoint.
The antiscorbutic factor is abundant in fresh foods, especially in vegetables and fruits, and to a considerably less extent in animal foods, such as milk, meat and fish. Among the vegetables there is a marked distinction in potency. A beginning has been made in standardizing these various foodstuffs, in grading them approximately according to their antiscorbutic efficacy ([Table 3]). It should be remembered, however, that the importance of an antiscorbutic food depends not only on its intrinsic content of the antiscorbutic factor, but quite as much on the amount of the food which is eaten. For example, although potatoes possess only moderate virtue compared with orange juice, they are of greater practical value in view of the large quantities which are consumed and their availability when green vegetables are lacking. Furthermore, the fact recently brought out that the various vegetables, and perhaps the fruits as well, have considerably more value when they are fresh and young than when they are old, warns us not to carry our quantitative standardization too far.
Fruits and vegetables which are dehydrated have been found to have lost their antiscorbutic properties. This generalization is not without its exception, for it has been found that cabbage and tomato withstand drying well, and that if milk is dried under favorable conditions it retains a very large part of its antiscorbutic value. It may be stated that the outlook is bright in regard to dehydration, as the problem has not yet been thoroughly studied, and the process may be so improved that there will be little difference in the nutritional value between the fresh and the dehydrated food.
The study of antiscorbutic values points a lesson in regard to the methods of cooking vegetables. It has demonstrated that short cooking, associated with a high degree of temperature, is less deleterious than longer cooking at a low degree. In other words, that less damage is brought about by boiling or by steaming vegetables than by stewing them. Here age and freshness again play a rôle; in fact, a double rôle, as the older and tougher vegetables contain not only less antiscorbutic, but require more prolonged cooking.
In general, the belief is correct that canning destroys the antiscorbutic value of foods, but once more an exception must be made, for it has been found that acid foods, such as the tomato, withstand the canning process with but little loss of potency.
The field of antiscorbutic foodstuffs is one which is fertile for future investigation. The antiscorbutic status of milk heated to various heights of temperature and subjected to various degrees of aging furnishes problems of great practical importance. A lack of growth has been noted when antiscorbutics are given which have been subjected to a high degree of heat (e.g., autoclaved orange juice). Whether this is due to the destruction of some other growth factor is a question which has been raised by several experimental studies and requires an answer.
It is quite possible that we shall find useful antiscorbutic foods which at present are unknown or unappreciated. The recent introduction of the swede, of the canned tomato and of germinated pulses suggests and even renders this probable. On the other hand, the recognition of the comparative poverty of the antiscorbutic factor in lime juice shows the importance of putting each foodstuff to the experimental test.