=Lime Juice.=--Recently an investigation of lime juice has been carried out by Chick, Hume and Skelton. They were "unable to detect any significant protection in a daily ration of from 5 to 10 c.c. of preserved lime juice which was several months or a year or more old."

Crude lime juice of various ages had slight antis...o...b..tic value, affording only partial protection in a daily ration of 5 c.c. Even fresh juice was found not to be very efficacious compared with lemon juice.

The authors conclude that "the relative value of these two fruit juices deduced from the trials with monkeys is therefore in accord with that obtained in the experiments with guinea-pigs, _i.e._, the value of fresh lemon juice is approximately four times that of fresh lime juice." Holst and Froelich in 1907 carried out a similar but less extensive investigation. They also found that lime juice was unable to protect guinea-pigs from scurvy. Fuerst, a co-worker of Holst, continued this work, and in his article of 1912 stated that guinea-pigs should not be protected by a daily addition to their ration of 25 g. of lime juice; these guinea-pigs received a mixed diet consisting of dry vegetables, b.u.t.ter, almonds and malt extract. These two reports of the Norwegian investigators on this interesting subject should have attracted attention.

=Other Fruits.=--A word may be said in regard to some other fruits. The antis...o...b..tic potency of _raspberries_ was tested by Holst and Froelich (1912) and found comparable to oranges and to lemons. The juice was also highly resistant to heat, so that 10 c.c. of freshly-pressed juice were of protective value, even after it had been subjected to 100 or 110 C.

for one hour. Guinea-pigs which were thus treated showed no microscopic signs of scurvy in any of the ribs, in the tibiae or the femora.

TABLE 3 TABLE SHOWING THE RELATIVE DISTRIBUTION OF THE ANTIs...o...b..TIC FACTOR IN THE COMMONER FOODSTUFFS[*]

===================================================================== Cla.s.ses

Anti-

Cla.s.ses

Anti- of

s...o...b..tic

of

s...o...b..tic Foodstuffs

Factor

Foodstuffs

Factor ------------------------+---------+------------------------+--------- _Meat, Fish, Etc.:_

_Vegetables and Fruits:_

Lean meat (beef,

Cabbage, fresh

+++ mutton, etc.)

+

Cabbage, cooked

+ Liver

+

Cabbage, dried

Very Tinned meats

0

slight Beef juice

+

Swede, raw expressed

juice

++ _Milk, Cheese, Etc.:_

Lettuce

++ Milk, cow's, whole raw

+

Carrots, fresh raw

+ Milk, cow's, skim raw

+

Carrots, dried

0 Milk, cow's, dried

+

Beetroot, raw,

Less Milk, cow's,

Less

expressed juice

than + boiled

than +

Potatoes, raw

...

Milk, cow's,

Less

Potatoes, cooked

+ pasteurized

than +

Potatoes, dried

0 Milk, cow's, condensed

Less

Beans, fresh, raw

++ (sweetened)

than +

Onions

++

Lemon juice, fresh

+++ _Eggs:_

Lemon juice, preserved

++ Fresh

?0

Lime juice, fresh

++ Dried

?0

Lime juice, preserved

Very

slight _Cereals, Pulses, Etc.:_

Orange juice

+++ Wheat, maize, rice,

Raspberries

++ whole grain

0

Grapes

+ Wheat germ

0

Apples

+ Wheat, maize, bran

0

Bananas

Very White wheaten flour,

slight pure corn flour,

Tomatoes (canned)

++ polished rice, etc.

0

Linseed, millet

0

_Miscellaneous:_

Dried peas, lentils,

Yeast, autolyzed

0 etc.

0

Meat extract

0 Soy beans, haricot

Beer

0 beans

0

Cod liver oil

0 Germinated pulses or

Olive oil

0 cereals

++

Human blood

+ --------------------------------------------------------------------- [*] This table is a modification of one prepared by the Medical Research Committee

These authors also reported that they found _banana_ and _apple_ poor in antis...o...b..tic power, 30 g. daily being insufficient to protect a guinea-pig (Table 3). This was our experience with banana in the treatment of infants suffering from mild scurvy. The banana has been shown by Sugiura and Benedict to be poor also in the water-soluble vitamine. It would be of interest to determine the difference in vitamine content between the fully ripe and the unripe fruit.

In view of the fact that _grapes_ are used considerably in the treatment of infantile scurvy, it is of importance to realize that they are poor in the antis...o...b..tic principle. Chick and Rhodes found that three of four guinea-pigs receiving 20 g. daily developed scurvy; they rated the potency as ten times less than that of orange juice.

VEGETABLES

It is everyday knowledge that fresh vegetables are of great value in the protection from, and cure of, scurvy. The first experimental investigation of this subject was that of Holst and Froelich, published in 1907, and continued in a series of papers extending to 1916. These investigators tested the potency of a large number of vegetables by feeding them in varying quant.i.ties to guinea-pigs. They found that all vegetables have antis...o...b..tic value but to a markedly varying degree.

Cabbage, sorrel leaves, endive, head salad, and dandelion leaves, were found to be of most avail in protecting against scurvy, whereas carrots, cooked potatoes and cooked turnips, and cauliflower proved to be of less value. In general, it may be stated that the leafy vegetables have more antis...o...b..tic power than the roots or the tubers. This generalization, we shall see, is not without exception, _e.g._, the swede. Similar experimental work has been recently carried on by a group of investigators at the Lister Inst.i.tute, who have added considerably to our knowledge in this field. In all this experimental work cabbage has been found to be the most potent of the vegetables, and therefore experiments have centered about it just as in considering fruits the work has centered about orange juice or lemon juice. We shall, therefore, discuss in detail its reaction to heat and dehydration.

=Cabbage.=--Holst and Froelich found that 1 g. daily of fresh cabbage afforded nearly complete protection to guinea-pigs, and Delf has corroborated this work. This amount is sufficient to prevent the development of manifest scurvy, although it does not induce satisfactory growth. In this respect it is comparable to giving 1.5 c.c. of orange juice daily. If guinea-pigs take only 0.5 g. of raw cabbage, scurvy will develop; whereas 2 g. or more will promote satisfactory growth and no s...o...b..tic changes will be found on microscopic examination.

=Effect of Heating.=--Vegetables are of decidedly less antis...o...b..tic value when cooked than raw; cabbage, for instance, on being boiled is weakened about one-half. Heating to 110 C. for an hour destroys almost all of its antis...o...b..tic factor. Delf's tests did not show so great a loss. She came to the conclusion, of theoretical and practical value, that slow cooking at a low temperature is much more deleterious than rapid cooking at a higher temperature. Hess and Unger found that carrots lost much of their antis...o...b..tic power after boiling, and that this was the result of a true destruction, the vitamine not having been merely dissolved in the water of boiling; for if guinea-pigs consumed 40 c.c.

per capita of this water, they were not protected against scurvy (Fig.

11). Acidulating the water with 10 per cent. vinegar did not reduce the loss, an experience similar to that of others using citric acid or lemon juice.

_Vegetables cannot be considered from an antis...o...b..tic standpoint as a standard and uniform foodstuff, as they vary in their content of this factor according to their freshness and age._ This was demonstrated by means of feeding experiments with carrots. For example, 35 g. of old carrots, such as were used for feeding the laboratory animals, afforded but little protection after having been cooked in an open vessel for about 45 minutes, whereas the same amount of young carrots cooked this way protected the guinea-pigs. It is obvious that this distinction is of importance in evaluating the antis...o...b..tic content of the various foods, and in considering whether individuals and groups of individuals are receiving an adequate quota of antis...o...b..tic vitamine. It will be noted later that it is also of importance in connection with the potency of dehydrated vegetables. Recent experiments indicate that not only age, but the _degree of ripeness_ must be considered in appraising the food value of vegetables. Feeding experiments showed that tomatoes which were fully ripe were more potent than those which were slightly green.

Probably many other factors play a role in determining the richness of vegetables in vitamine. It may not be immaterial whether they are allowed to ripen on the vine or shrub, or mature subsequently. The nature of the soil may also affect the antis...o...b..tic quality of the vegetables or fruit. So that it is evident that we must not be schematic in considering this question, and must realize that a table of antis...o...b..tic values, such as accompanies this text (Table 3), does not furnish definite and inflexible values.

There is a marked difference between _vegetables and vegetable juices_ in keeping quality, and in their reaction to heat and to acid. In general, it may be stated that the juices are much more sensitive. Holst and Froelich brought out this point in 1912 and enlarged upon it in their publication of 1916. The different juices vary greatly in this respect; for example, dandelion juice is acutely sensitive to heat, whereas sorrel leaves withstand high temperatures very well. In regard to these differences an a.n.a.logy may be drawn to the fruit juices. Lemon, orange and raspberry juices are markedly thermostable, but lime juice is weakened markedly by heat. Many of these juices are protected by the addition of acid--5 per cent. of lemon juice increasing the thermostability of cabbage juice--whereas, as we have stated, little is gained by cooking vegetables in an acid medium.

=Potato.=--The civilized world is dependent for its quota of antis...o...b..tic foodstuff largely upon the potato. It might be thought, therefore, that this would signify that the potato is endowed with great antis...o...b..tic power. Such is not the case, however, as demonstrated both by laboratory tests and clinical experience. Considering its importance, there have been surprisingly few feeding experiments carried out with potato. Holst and Froelich (1912) found that 17 g. of potatoes, steamed at 100 C. for 30 minutes, afforded but slight protection, and that it required 20 g. to fully protect a guinea-pig. Givens and Cohen failed to ward off scurvy by means of cooked potatoes fed to the equivalent of 5 g. of the raw vegetable (guinea-pigs will not eat raw potatoes). There are no accurate figures as to the quant.i.ty of potatoes needed to protect a human being from scurvy. The statement of Doctor Guy, however, who after careful study of convicts' diets, concluded that 14 ounces daily would protect them from scurvy (if the ration included one ounce of other fresh vegetable and 4 ounces of meat), is probably close to the mark.[41] With the experience that potatoes play such a significant role in the prevention of scurvy, how are we to interpret the fact that they are only mildly antis...o...b..tic? Potatoes are consumed in very large amounts; in the Temperate Zone probably twice as many pounds of potatoes are consumed during the winter as of all other vegetables combined (Fig.

1). It is evident, therefore, that in a practical evaluation of antis...o...b..tic foodstuffs, not only the intrinsic antis...o...b..tic potency must be considered, but also the quant.i.ty of the vegetable or fruit consumed.

[41] Dr. Guy's evidence, Report of the Lords Commissioners of the Admiralty on the Outbreak of Scurvy in the Recent Arctic Expedition--1877 (cited from Chick and Hume).

=Swede.=--We cannot leave the consideration of vegetable antis...o...b..tics without adding a few words as to the value of swede juice,[42] which has been recently highly recommended by Chick and Rhodes, who found it comparable to the cabbage and the onion, and even to orange juice. For example, 25 c.c. of raw swede juice were equivalent to 1.5 g. of raw cabbage. It is, therefore, more potent than the juice of raw carrot, and far more efficacious than the juice of the beetroot (Table 3). Tests carried out with this antis...o...b..tic in infant feeding seemed to show that it is of value in this field. The authors believe that the potency of vegetables is closely a.s.sociated with certain botanical species, and that in this way the marked virtue of the swede can be explained, as it belongs to the natural order of Cruciferae, which includes also the cabbage, the scurvy gra.s.s and the cresses. If, however, this is a rule of nature, it is difficult to explain the marked difference between the lime and the lemon, which are both varieties of Citrus Medica.

[42] The swede is a root vegetable of the natural order Cruciferae. It is grown to a large extent in England, but is practically unknown in the United States.

=Dehydrated Vegetables.=--For hundreds of years fresh vegetables have been dried to serve as food during the winter months and have fulfilled a useful purpose on account of their small bulk and great food value.

The question for us to consider, however, is whether dehydrated vegetables still retain their antis...o...b..tic quality and can be counted on to supply this factor in the dietary. At present this subject is engaging the attention of laboratory workers as well as of practical diet.i.tians and food hygienists. The experience of the past is not happy in this regard. In the Medical and Surgical History of the War of the Rebellion we read as follows: "A s...o...b..tic tendency was developed at most of our military posts during the winter season, after the troops had been confined to the use of the ordinary ration with desiccated vegetables. The latter in quant.i.ties failed to repress the disease." In spite of this and similar military experiences[43] the employment of dehydrated vegetables was urged recently for rationing our soldiers, the claim being made that "by simply soaking in water and boiling in the same water these vegetables are brought back to the condition of fresh vegetables." Both in this country and in England there was strong propaganda during the war to dehydrate vegetables on an enormous scale and to subst.i.tute them for the fresh food.

[43] "We find the College of Physicians at Vienna sent to Hungary great quant.i.ties of the most approved antis...o...b..tic herbs dried in this manner; which were found to be of no benefit. Many of these would have their virtues as little impaired by drying as spinage, _e.g._, marsh trefoil. Kramer tried almost every species of dried herbs to no purpose." (Treatise on The Scurvy. James Lind, London, 1772, p. 143.)

[Ill.u.s.tration: FIG. 12.--Hay, oats, water _ad libitum_, and 7 g. of dehydrated carrots dried at a room temperature of about 130 F. about 1 month previously. All animals developed scurvy. The marked gain in weight when an equivalent amount of fresh carrots was subst.i.tuted for the dehydrated vegetable corresponded to the disappearance of s...o...b..tic signs. Guinea-Pig B 951 did not receive fresh carrots, as it was evidently ailing at the time the second period began.]

Experimental investigation on this subject may be summarized as showing that vegetables dried according to present methods lose their antis...o...b..tic value as the result of dehydrating (Fig. 12), and that they become still more impoverished as the result of aging. We should not sweepingly condemn the principle of dehydration, as very possibly some slight modifications in the process may be devised which will counteract the deteriorating influence. In their paper of 1912, to which reference has been made so often, Holst and Froelich reported that potatoes, carrots, peas, lentils and almonds have practically no protective value after they are thoroughly dried. In two reports--one giving the results of feeding various brands of dehydrated carrots to guinea-pigs, and the other of an attempt to cure scurvy in babies by means of these carrots--we also came to the conclusion that the antis...o...b..tic factor had been almost completely destroyed. Givens and Cohen (1918) found that even cabbage dried at a low temperature retained only a small amount of its potency after a month, and Delf and Skelton came to practically the same conclusion, also noting that the cabbage on being kept, steadily lost what little of the antis...o...b..tic factor had survived the drying process. The same was true of the fat-soluble factor. These authors made an observation which may prove of value in helping to solve this problem, namely, that "the residual amount is distinctly greater if the cabbage is plunged into boiling water before drying." This protective action of heat they suggest may indicate that: "Some at least of the destruction may be due to the activity of an enzyme or other body originally present in the living tissue."

Another observation which may prove of practical value in rendering dehydrated vegetables the nutritional equivalent of the fresh vegetable is that when the carrots selected for dehydration are young and fresh a product is obtained which possesses decided antis...o...b..tic power. In this connection the following statement by Falk and his co-workers in a study of the enzyme action of vegetables and the effect of dehydration is significant: "In considering these enzyme results, it may be pointed out that the state of ripeness and the age of the vegetable undoubtedly influence the activities."

The most promising dehydration experiment has been conducted by Holst and Froelich and was published in 1916 in a paper which has pa.s.sed unnoticed. They dried white cabbage so that it retained its antis...o...b..tic properties, and, to a large extent, its color and taste, for a period of two years. This result was accomplished by keeping out all moisture and preventing hydrolysis,[44] a method which is employed in preserving ant.i.toxins, toxins and agglutinins. It is by far the most encouraging test reported, and should be made the basis of further work by those actively interested in perfecting dehydration.

[44] The cabbage was subjected to a preliminary drying for 8 days at 37 C. It was then put in an air-tight desiccator which contained a dish of phosphorus pentoxid. (The pentoxid was replaced for several weeks until it ceased to liquefy.) It was then placed in cylinders which had been rendered air free by means of a suction pump and which contained phosphorus pentoxid. This was kept at 37 C. and examined after 10, 18 and 26 months. A similar result was not obtained when calcium chlorid was employed, the temperature held at 37 C. and the cabbage was kept in an air-tight cylinder rather than in a vacuum. However, under these conditions if the cabbage was placed in the ice-box at a temperature of 4, 10 or 12 C. the antis...o...b..tic property was conserved after boiling.

[Ill.u.s.tration: FIG. 13.--Cure of scurvy by the addition of canned tomato. In this case, as frequently, the alleviation of symptoms preceded the gain in weight.]

=Canned Food (Tomatoes).=--In the course of canning, as in dehydrating, most vegetables and fruits lose their antis...o...b..tic properties. A general denunciation, however, of all canned foods is incorrect, as there are exceptions to this rule. It has been shown by Hess and Unger that canned tomatoes possess a high degree of antis...o...b..tic power (Fig.

13), and it is probable that most of the acid fruits and vegetables are able to withstand the canning process. It was found, in an experiment embracing many series of guinea-pigs, that 4 c.c. daily of strained, canned tomato are sufficient to afford protection, even when a lot was used which had been prepared a year previously. This is indeed remarkable, considering that the food undergoes a two-fold heating in the course of canning, during one of which ("processing") the temperature is raised to fully 230 F. Tomatoes have another advantage over most other vegetables in that they are richly endowed with the water-soluble vitamine, as shown by our tests on pigeons suffering from polyneuritis, and by the experiments on rats of Osborne and Mendel, who found tomatoes far superior in this respect to turnips, onions, beetroots or beans. They are also rich in the fat-soluble vitamine. In view of the availability of canned tomatoes and their excellent keeping quality they are well suited to an extended use as an antis...o...b..tic. In the subsequent chapter we shall discuss their employment in infant feeding and in the army ration.

=Germinated Cereals and Pulses.=--In 1912 Fuerst reported that although the resting seed--the cereal grain, the pea, bean and lentil--are poor in antis...o...b..tic vitamine, they develop this principle as soon as they germinate. They possess, in other words, latent antis...o...b..tic properties, and are potentially antis...o...b..tic. This observation is not only of scientific interest but of practical value, as these pulses are well suited for transport and do not readily deteriorate. For this reason, Chick and her co-workers at the Lister Inst.i.tute, who were searching for an antis...o...b..tic foodstuff for the army, directed their attention to the utilization of the pulses. In the course of a thorough investigation (1919) they found that although it required 30 to 40 g.

daily of dry green peas to prevent scurvy in the guinea-pig, a consumption of 10 g. of the germinated peas afforded satisfactory protection.[45] The soaked seeds have an antis...o...b..tic value comparable to many of the fresh vegetables; by no means as great as cabbage, but somewhat greater than that of carrots. As the result of cooking, their potency was found to be reduced about 75 per cent. We shall have occasion to refer to this antis...o...b..tic food in the chapter on treatment in connection with the rationing of armies.

[45] The pulses, after having been soaked in water for 24 hours, were kept moist, with access of air, for about 48 hours at room temperature, and during this time germinated, developing a radicle usually about 1 cm. in length.

=Meat and Eggs.=--As has been stated, animal tissues are distinctly inferior to fruits and vegetables in the antis...o...b..tic principle. As there has been no accurate evaluation of these foods--the only test being one by Chick, Hume and Skelton, where 10 c.c. of raw beef juice failed to protect guinea-pigs--we have to depend upon clinical experience for our knowledge. Beef juice is highly rated by physicians in the prevention of infantile scurvy, but it is probably far less potent than vegetables or fruit juices. The Arctic explorers, and many who have lived in the Arctic regions, agree that the inhabitants are protected from scurvy during the winter months by their diet of fresh meat and fish. The Admiralty Enquiry on the outbreak of scurvy in the Arctic Expedition of 1875 reported that a large ration of meat is necessary to afford protection. Curran (1847) described three cases admitted to the hospital in the great Irish epidemic of that year, where the diet previously had included three-quarters of a pound of meat on five days of the week. From these and similar experiences the conclusion is manifest that the divergence of opinion regarding the value of meat is based upon quant.i.tative differences in the rations. Evidently, if sufficient meat is provided, the development of scurvy will be obviated.

Another factor which must be borne in mind is that those who refer to meat in the Arctic regions refer to fresh raw meat, which is a far more valuable antis...o...b..tic than the ordinary cooked meat.

There is almost no experimental data on the antis...o...b..tic value of _eggs_. Hard-boiled eggs were fed to guinea-pigs and it was found that 9 g. per capita daily was insufficient to protect them. An attempt was also made to cure infantile scurvy with a daily addition of one raw egg to the dietary, but without avail. It is possible that fresh raw eggs have an antis...o...b..tic value comparable to meat, but the large quant.i.ty required makes dependence upon them impracticable.

=Beer and Alcoholic Beverages.=--For generations beer has been highly regarded as an antis...o...b..tic. Captain Cook prized it greatly and always supplied his men with a freshly-made infusion of malt called "sweetwort." Lind writes: "Beer and fermented liquors of any sort will be found the best antis...o...b..tic remedies" (p. 76). He refers at different times to the value of spruce beer, ale, wine and other vinous liquors. In his excellent book on "Military Hygiene," Munson writes: "Good beer and wine have decided value, also vinegar." On the other hand, recent scientific experiment has shown that beer has practically no antis...o...b..tic value. There is but one study on this subject, that of Harden and Zilva, which is quite convincing. They found that guinea-pigs and monkeys developed scurvy in spite of the fact that they received, respectively, 50 c.c. and 180 c.c. of beer daily. They conclude, as a result of their experiments, that "bottled ale and stout and fined beer as brought on to the market, are lacking both in antineuritic and antis...o...b..tic accessory factors, and that kilned material is also wanting in these two principles." The apparent contradiction between practical experience and laboratory investigation in regard to beer is due to a difference in the process of brewing. Cook and Lind and the older authors refer to freshly-made beer, whereas the modern beer which was tested in the laboratory was made from "high-dried" material. The antis...o...b..tic potency of beer as formerly used was due to its preparation from freshly-germinated grain and its consumption shortly after brewing. d.y.k.e tells us of an interesting incident ill.u.s.trating the importance of this distinction. In the recent war an outbreak of scurvy occurred among the Kaffir labor battalion in France. At home these natives consume a large amount, as much as three gallons a day, of Kaffir beer, which is made from freshly-germinated corn, and is consumed shortly after it is made. The French prepared a similar fermented beverage for their South African laborers, the sole difference in preparation being that the process of germination had been omitted for reasons of convenience. Scurvy resulted, a disorder which is practically unknown among the natives at home.

=Miscellaneous Foodstuffs.=--During the past few years a great many different kinds of foods have been tested in the laboratory for their antis...o...b..tic value. It will be well for completeness' sake to say a word about them, although they have been found to possess little or no antis...o...b..tic properties. The studies of Holst and Froelich showed definitely that all the cereals--oat, barley, rye, maize, and preparations made from the bran or from the endosperm--are devoid of antis...o...b..tic vitamine. Cohen and Mendel added 3 per cent. of calcium lactate or sodium chloride, or 5 per cent. of b.u.t.ter, without enhancing the value of oats in this respect.

[Ill.u.s.tration: FIG. 14.--Failure of yeast as a prophylactic; latent scurvy promptly yielding to orange juice.]

As is well known, yeast possesses the water-soluble vitamine in marked concentration. It is natural, therefore, that its antis...o...b..tic power was put to the test, especially as it has been accorded therapeutic value. Hess and Unger showed that autolyzed yeast was of no value in the cure of infantile scurvy (Fig. 14); Chick and Hume (1917) and Cohen and Mendel (1918) came to the same conclusion in regard to guinea-pig scurvy, making use of autolyzed yeast, yeast extract and dried brewers'

yeast.

In view of the fact that cod liver oil is practically a specific for human rickets, Hess and Unger tried the effect of this oil both in infantile scurvy and in that of guinea-pigs. It proved to have no protective or curative value. The animal experiments were confirmed by Cohen and Mendel. The use of olive oil also proved futile.

Pitz in 1918 reported that in animal experiments he had found that lactose was able to protect against scurvy, and attributed this result to its power to alter the intestinal flora. We shall not enter into a detailed discussion of this question, as the study was carried out on a ration embodying unlimited and uncontrolled amounts of milk, and it has since been shown that the apparent cure was due to an increased consumption of milk by the animals in the progress of the experiment.

Cohen and Mendel, Harden and Zilva, Hart, Steenbock and Smith (1919) all failed to protect or to cure their animals with lactose when they were placed on a ration which was definitely measured and limited. Hess and Unger failed to cure infantile scurvy by means of lactose.

It has been suggested that scurvy is due to a lack of secretion of the endocrine glands, a question which will be referred to again in considering the relation of scurvy to other "deficiency diseases." With this idea Ingier added thyroid, hypophysis, thymus and parathyroid to the food of guinea-pigs, or gave it parenterally. She was unable to observe any beneficial results. Jackson and Moore met with the same result on feeding desiccated thyroid gland. We may add that we gave dried thyroid and also parathyroid glands in the treatment of infantile scurvy without effect.

CONCLUSIONS

Any consideration of the question of antis...o...b..tic 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 antis...o...b..tic 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 quant.i.tative viewpoint.

The antis...o...b..tic 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 antis...o...b..tic efficacy (Table 3). It should be remembered, however, that the importance of an antis...o...b..tic food depends not only on its intrinsic content of the antis...o...b..tic 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 quant.i.ties 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 quant.i.tative standardization too far.

Fruits and vegetables which are dehydrated have been found to have lost their antis...o...b..tic 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 antis...o...b..tic 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 antis...o...b..tic values points a lesson in regard to the methods of cooking vegetables. It has demonstrated that short cooking, a.s.sociated 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 role; in fact, a double role, as the older and tougher vegetables contain not only less antis...o...b..tic, but require more prolonged cooking.

In general, the belief is correct that canning destroys the antis...o...b..tic 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.