Recently an historical inquiry has appeared in an article by Chick, Hume and Skelton as to the antiscorbutic virtue of limes and lemons. This sketch is of exceptional interest because it treats of the oldest and most cherished antiscorbutics, and particularly because it has unearthed a peculiar fallacy in their connection. As they state, there would appear to be every reason for believing “that the use of so-called lime juice was responsible for the disappearance of scurvy from the British navy in the first decade of the nineteenth century.” It would seem, however, that the lime juice which gained this great reputation in the navy some 125 years ago was in reality lemon juice, and that it was not until about 50 years ago that lime juice was really used. These authors show—by one of those striking human experiments which, occasionally, is available—that in a Polar exploration which was organized in 1850 lemon juice was issued to each man, and that no case of scurvy developed, whereas in a similar expedition which went out in 1875 lime juice was issued and scurvy developed the following spring with great severity among the sledge crews. This investigation, therefore, seems to prove that lime juice, the prototype of antiscorbutics, has been accorded a false position; that in reality the sailors of the past have been protected by lemon juice.
Antiscorbutic Foods.—As far as has been ascertained, the antiscorbutic food factor exists in all fresh vegetable and animal tissues, being present to a far greater degree in the former than in the latter. It is distinguished by being associated in nature with cells which are the seat of active metabolism, just as the water-soluble vitamine is associated mainly with cells which are in an inactive or dormant state. Vegetables or fruits may be mildly or highly antiscorbutic; there is indeed a remarkable difference in their content of antiscorbutic factor or vitamine. They vary widely also in the degree to which their potency is affected by physical or chemical conditions. In this chapter the most common animal and vegetable antiscorbutic foodstuffs will be considered and the effect which processes such as drying, canning, change of reaction, etc., exert on their specific value. Their therapeutic application in the prevention and cure of scurvy will be considered in a subsequent chapter. Until recently our knowledge of this subject was empirical and inaccurate; as the result of scientific work, however, carried out during the past few years in different parts of the world, quantitative and comparative figures of antiscorbutic food values have been evolved.
Milk.—It is important to have as accurate an idea as possible of the value of milk as an antiscorbutic, as the infant depends on it during the first months of its life for a supply of this essential factor. Considerable attention has been paid to this question in the last few years, and recent reports tend to confirm the former estimations which had been overlooked and forgotten. In 1847 Curran wrote that in the Irish epidemic of this year they had admitted to the Dublin Union Hospital 80 cases of scurvy which had been on a diet which included one pint of milk daily, but was deficient in vegetables. From this experience he realized that milk was not rich in the principles which protect against scurvy. In the following year Parkes came to the same conclusion, stating that 500 to 750 c.c. of raw milk did not always suffice to prevent scurvy. In addition to these opinions concerning adults, similar conclusions have been drawn from clinical experience with infants. Barlow (1894) realized that a small amount of milk was insufficient to protect against scurvy. Still writes: “The antiscorbutic power of fresh, unboiled milk is evidently slight.” In 1914 Hess and Fish pointed out that “milk must not be considered as having potent antiscorbutic properties.” Nevertheless, when this question was raised recently by the experimental work of Jackson and Moore, and that of McCollum and Pitz, it was not appreciated that, like other antiscorbutics, milk must be regarded from a quantitative standpoint, and that, as it is a weak antiscorbutic, its effect must depend largely on the quantity consumed.
The first laboratory work on this subject was that of Froelich in 1912, who showed that guinea-pigs could be protected by an exclusive diet of fresh milk, and that raw milk is more effective than heated milk. In his work, the amount of milk taken by the animals was not measured, so that it is impossible to glean from it more than these general conclusions. In the following year, as a result of some quantitative experiments, Funk stated that he was able to protect guinea-pigs with 50 c.c. of fresh milk in addition to an oat diet. This estimate, as subsequent workers showed, is too low. Chick, Hume and Skelton were the first, however, to investigate the antiscorbutic potency of milk in a systematic and convincing manner. They demonstrated that if the daily consumption of fresh milk was less than 50 c.c., a guinea-pig died almost as quickly as if it received no milk; if the daily quota varied from 50 to 100 c.c., a greater or less protection from scurvy was observed, varying proportionately with the amount consumed; if 100 to 150 c.c. were taken daily, which practically amounts to a complete milk diet, satisfactory growth and development occurred, and no symptoms of scurvy were observed. This represents in a general way the present conception of the antiscorbutic power of milk. In passing, it may be remarked that it is not altogether clear why 50 c.c. of milk do not afford partial protection, and prolong the life of the animal for a definite length of time. The authors conclude that “milk is evidently a food poor in the antiscurvy accessory factor, and a ration large in comparison with that of other antiscorbutic materials is necessary to afford satisfactory protection from scurvy.” The error must be avoided, however, of regarding milk as a standard article of diet containing a definite and specific amount of vitamine per cubic centimetre. It will be shown later that this point of view cannot be taken in regard to vegetables, and it is probable that it cannot be assumed for milk.
A general conception of the antiscorbutic potency of cow’s milk may be gleaned from the fact that it requires a minimum of about sixteen ounces (500 c.c.) daily to protect an infant from scurvy or to cure it. Twelve ounces have failed to effect a cure in several instances, although the milk was raw and of the best grade. If it is pasteurized, a larger quantity is required, depending upon various conditions connected with the heating process and upon the age of the milk, circumstances fully discussed in relation to etiology. Thus it becomes evident that pasteurized milk assumes a two-fold rôle, acting as an antiscorbutic if little of its vitamine content has been destroyed and if a large quantity is consumed, or leading to the development of scurvy when one or both of these conditions is unfavorable. The same holds true for milk which has been boiled for a short period. If the milk has been heated twice, it tends to produce scurvy; if it is condensed, the greater part of its antiscorbutic value is destroyed.
It seems necessary to emphasize again the important fact that dried milk may possess marked antiscorbutic potency, depending on the method of preparation ([Fig. 11]). As stated, sixteen ounces of milk dried by the Just-Hatmaker process cured scurvy promptly, in spite of the fact that the milk had been dried six months previously. Here, therefore, is a food of high caloric value, compact, antiscorbutic, and stable. The fact that milk, in spite of drying, retains this labile vitamine for so long a period, demonstrates that it is available in the most remote parts of the world, and that the possibilities of its transportation are unlimited.
Little is known regarding the antiscorbutic content of the milk of the various domestic animals. Some claim that goat’s milk is notably rich in this particular, but experiments with it are too few to warrant conclusions. Lind writes: “Goats, of all animals, afford the richest whey, possessed of the greatest antiscorbutic virtue . . . which in a singular manner restores the constitution when weakened and impaired by scurvy.” Human milk possesses about the same potency as cow’s milk, as mentioned in the discussion of the occurrence of infantile scurvy in countries where the adult form is endemic. Twelve ounces of human milk, from a woman on a liberal and varied diet, barely sufficed to alleviate the symptoms of a case of moderate intensity.
FRUIT JUICES
Orange and Lemon Juice.—The most thoroughly studied antiscorbutic foods are orange and lemon juice, which have been singled out because they contain the antiscorbutic factor in the highest concentration. It has been ascertained through the work of various investigators that guinea-pigs require about 3 c.c. daily of either of these juices to protect them from scurvy, but that about half this amount is sufficient to prevent the manifestation of clinical signs.
Both of these juices withstand heat remarkably well. Orange juice can be boiled for 10 minutes without noting any diminution of its antiscorbutic value, and lemon juice heated to 110° C. without appreciably losing its efficacy. However, orange juice undergoes some change as the result of being heated in an autoclave for 45 minutes at a temperature of 110° under 10 to 15 pounds pressure. Although 6 c.c. of this heated preparation were able to prevent the development of scurvy, the guinea-pigs did not gain nearly as well as those which received 3 c.c. of the unheated juice. It seemed as if there was a destruction of some factor apart from the antiscorbutic principle.