VITAMIN A, EFFECT OF LOSS IN DIET DURING EXPERIMENTS
Vitamin A can be used to demonstrate how it has been proved that such things as vitamins exist, how their chemical nature is tested, how their presence or absence in particular food products is determined, and why it is believed that their omission from the diet results in certain diseases or deficiencies.
Scientific investigation of diet was not begun so very long ago. One of the first investigators was Carl Voit. He suggested that a good way to observe the action of foods would be to feed animals mixtures of pure extracts of the three food principlesprotein, fat and carbohydrates.
This was done using milk protein and substituting lard for milk fat, adding sugar for the carbohydrate. Then a puzzling thing happened. On this diet, which was completely adequate according to all the known facts, the animals under observation showed loss of weight and a general decline. When milk fat was put in the mixture to re-place the lard the weight was restored and the animals perked up again.
“Lard,” as one of the investigators said, “is as much of a fat as butter fat. When our investigators found the substitution of lard for butter fat produced loss of weight and general decline, they attributed the deficiency of lard not to the fat itself, but to something accompanying the butter fat and not the lard.”
The “something” is Vitamin A.
We see then that it is associated with fatsfat-soluble. It is re-moved from its source by fat solvents, such as ether and chloroform.
In order to prove whether a given food contains Vitamin A the food is fed to experimental animals, usually albino rats, and their behavior observed. Two general sorts of tests are used. The most convincing is the curative test. For this the animal is fed a diet complete in every respect except that food known to contain Vitamin A is excluded. When signs of Vitamin A deficiency occur the animals are then fed the food under investigation. If the signs disappear it is concluded the food under investigation contains Vitamin A.
The most striking result of the omission of Vitamin A from the diet is the development of an infection of the eye. This has occurred in humans. In fact omission of milk fat, or butter, from the diet of children will result in the condition with great regularity.
When it is finally isolated Vitamin A will probably be found to be yellow in color. It is found in carrots, and corn with yellow kernels contains more than corn with white kernels.
The foods which contain the most Vitamin A are butter, cream, carrots, cod liver oil, eggs, spinach and watercress.
Cooking does not destroy any considerable amount of it. Nor does canning, or home preserving.
VITAMIN B IS OBTAINED IN WELL BALANCED DIETS
A correspondent, P. E. F., writes: “A newspaper of June announced the segregation of pure vitamin B in crystal form. Early experiments seem to show that this substance has great value in the treatment of neuritis. It was reported to the American Medical Association by Dr. M. G. Vorhaus and others of Columbia University and New York City.
“As some of your recent articles have dealt with the relationship between diet and neuritis, can you tell me whether crystalline vitamin B is available?”
Williams previously had found that certain chemical compounds, intimately connected with a betaine-like ring, were able to dissipate the neuritis of fowls, induced by Vitamin B deficiency, so he advanced the hypothesis that some such structure would be found to correspond to the formula of Vitamin B. So far as I know, none of these products are available for general clinical use.
The demonstration of the crystalline structure of Vitamin B is not so important from the standpoint of having a pure product for treatment purposes, as from the standpoint of theory. It was not long ago that scoffers used to ask, “Who knows what the vitamins are?” Now we can answer as accurately as if we told someone water is H2O.
VITAMIN CORRECTS CONDITION
Vitamin B in its natural state is perfectly capable of correcting any conditions caused by its deficiency in the diet.
Answering another correspondent, B. M., who wants to know what foods contain Vitamin B, it is very widely distributed in plant and animal materials commonly used as food. Milk is one, and I know of no report that indicates that milk has ever been found deficient in Vitamin B. Yeast is another, although less rich than wheat; rice and cereals so long as they are unmilled or unprocessed. In other words, so long as their outer shell remains on.
In the case of wheat flour, this outer shell is removed in milling to make white flour, but whole wheat, and hence whole wheat bread, contains the vitamin. Bran, which is simply the shell of the wheat removed in milling, contains it in concentrated form.
White bread, however, has the Vitamin B re-added to it in the yeast, and if prepared with milk this adds more.
Vitamin B is destroyed by heat, but not by the amount of heat produced by ordinary cooking.
The question has arisen whether we get an adequate amount of Vitamin B in our average diet. It has appeared in experiments, where the concentrated vitamin was added to the diet, that the people to whom it was fed only realized their subnormal state of health by contrast with the improvement which followed the use of a higher Vitamin B content.
One result of low Vitamin B amounts in the diet is impaired appetite. In animals and humans this is corrected by Vitamin B concentrates.
But only when the diet contains a preponderance of artificially refined food is there likely to be a real Vitamin B deficiency in the diet.
VITAMIN C, IN FRESH FRUIT, PREVENTS DISEASE OF SCURVY
When Jacques Cartier, in 1536, attempted to find the Northwest passage to the golden land of Cathay, he discovered the St. Lawrence river. While exploring his crew fell sick of “a strange and cruell disease. Their legges swel, and all their skins spotted with spots of blood of a purple colour, their mouthes became stincking, their gummes rotten.”
Cartier learned from an Indian chief that they could be healed by eating the juice and sap of a certain tree. When branches of this tree were brought none of the men at first “durst taste of it, except one or two, who presently recovered their health.” Then the others did the like and were “delivered of that sickenes.”
The disease was scurvy. The tree was called the ameda tree and may have been sassafras, or “the large, swampy American spruce tree.”
It was later that another navigator, James Lind, proposed lemon juice as a cure. And still another, Captain James Cook, proved that scurvy could be prevented by a daily ration of lemon or orange juice.
Scurvy was once a very prevalent and fatal disease. Sailors on long voyages, because of the restricted diet, were attacked.
In 1882 Barlow, an English physician, proved that the same disease attacks infants. The cause of the disease is a deficiency in the diet. If fresh fruits and vegetables are omitted from the diet scurvy develops.
The food substance, the lack of which will cause scurvy, is called Vitamin C.
Scurvy, though rare, will develop today any place, in anyone who subsists for any length of time on a diet lacking in Vitamin C. It increased greatly in the military and civilian population during the World War. The fact that the disease is so rare today is due to our changing diet, which has in the last 50 years broadened greatly in its inclusion of fresh foodsmilk, fruit and vegetables. In these times it is far commoner to see the disease in infants than in adults.
Vitamin C is soluble in water, like Vitamin B, and unlike A and D, which are soluble in fat.
Vitamin C is found in so many foods that you would have to work pretty hard to plan a diet for an adult which left this vitamin out.
It is, however, easily destroyed by heat, and we have emphasized above that it is found in fresh (uncooked) foods. Home preserving usually destroys it in the fruits and vegetables put up for winter consumption. Commercial canneries have been able to overcome this by heating their products in a vacuum. This exclusion of oxygen prevents the destruction of Vitamin C. Most commercially pre-served foods contain a good quantity of this anti-scurvy vitamin.
There is always danger that an infant will not get a good supply if fed on milk alone, because the amount of Vitamin C varies greatly in different milk samples, depending on the pasturage of the herd. The safest thing is to add Vitamin C to the baby’s diet in the form of a teaspoonful of fresh orange juice or tomato juice.
VITAMIN D Is DISCOVERED CONTAINED IN COD LIVER OIL
For many years cod liver oil was regarded as a good general tonic. When very scientific physicians asked the old practitioners exactly how it worked and what it did, why it was different from any other fat, the old fellows were forced to confess that they did not know, but they still seemed to think it toned people up, especially babies.
Then a Professor Mellanby, in England, reported in 1918 that he could produce that familiar old disease of babies, rickets, in puppies by feeding them on a diet of nothing except cereal and skimmed milk. Rickets, to put it very briefly, is a disease in which the bones remain soft, and in which lime salts are not deposited in them. Mellanby’s puppies, when x-rayed, were seen to have bones which resembled very closely the bones of babies with rickets.
When he added cod liver oil to the puppies’ diets rickets failed to appear. This also happened when certain other fats were used, and Mellanby concluded that the substance which prevented rickets was Vitamin A, which, as we have seen, is also fat-soluble.
However, an American nutritionist, McCollum, in 1922, proved that Vitamin A was a separate substance. He passed a stream of oxygen through hot cod liver oil. Vitamin A is destroyed by this procedure, but the cod liver oil so treated would still prevent rickets in dogs. The conclusion was that it contained some other substance which resisted destruction by oxygen. This substance was named Vitamin D.
About the same time a German physician, Huldschinsky, working in Berlin during and directly after the World War, announced that rickets could be prevented and cured by sunlight and ultra-violet radiation. This fact, which greatly puzzled the investigators of the dietary origin of rickets, really furnished the clue to the nature of Vitamin D.
Hess, of New York, and Steenbock, of Wisconsin, independently showed that the substance which prevents and cures rickets can be produced in a number of animal and plant structures by exposure to the rays of a mercury vapor lamp, or a carbon arc lamp. The sub-stance which is thus activated has been found to be ergosterol. It is found in small quantities widely in nature. One place where it is found is the human skin, and sunlight acting on ergosterol in the skin produces Vitamin D.
The most certainly available source of Vitamin D is probably a cod liver oil of good potency. It may be present in egg yolk and in cream and butter, but whether it is or not depends on the living and feeding conditions of the animals from which these foods are obtained. Vitamin D, indeed, is of all the vitamins the least certain to be present in an average diet.
Fortunately it can be produced artificiallyby exposing ergosterol to sunlight or ultra-violet light. It is the only one of the vitamins that can be manufactured. The name of the manufactured product is viosterol.
The way the amount of Vitamin D present in any food sample is measured is to produce rickets in rats. Then the animals are fed the food to be tested. By the rapidity of their recovery the potency (or, in other words, the amount of Vitamin D present) of the product is determined.
NEWER VITAMINS E AND G LESS KNOWN TO SCIENTISTS
The four fundamental vitaminsA, B, C and Dare probably associated in food substances with several other similar products.
Thus Vitamin B, early in its investigation, was considered a single kind of substance. It was considered to have growth-promoting properties and also the power to prevent beri-beri. Then it began to be evident that it also prevented (and cured) the disease called pellagra. During the investigation of this possibility it was discovered that the old original Vitamin B consisted of two different substances. One, for instance, was destroyed by heat : that was the part which promoted growth and prevented beri-beri. The other resisted heat: it also promoted growth, had no influence on beri-beri, but did seem to prevent pellagra. To this latter the name Vitamin G has been given. (It is sometimes referred to as B2.)
It is further probable that Vitamin G is a complex and the name Vitamin Y has been suggested as one of its parts. The present uncertainty in the minds of scientists concerning the possible properties of Vitamin G is a good illustration of the great benefits which may soon accrue from research in the vitamins.
For instance, Dr. Sherman recently reported to the American Chemical Society that Vitamin G seemed to have a youth-prolonging property. Which prompted a prominent columnist to demand what foods contained Vitamin G. Dr. James A. Tobey informed him that milk, yeast and green vegetables yield it.
It is also probable that Vitamins B and G increase appetite, in-crease the flow of milk in any animal mother and are good for the hair (if any).
Vitamin E is another newcomer in the fold. When absent from the diet of animals it results in sterility. This has not yet been proved for man. It is found in lettuce leaves, alfalfa, watercress and spinach.
Probably before long it will be found that the vitamins influence a number of rather vague and complicated bodily functions. When I say “vague” I mean vague in our mindsthings we take for granted and do not ordinarily define to ourselves as having any definite mechanism. Such as growth, resistance to infection, hardening of the teeth, resistance to fatigue, prolongation of vigor, etc.
As yet it cannot be said that taking extra amounts of the vitamins will double or triple their activities. Very little of each one is required in the daily diet. This small amount does as much of the work we expect of each vitamin as very large quantities.
Our columnist cannot extend youth prolonging indefinitely by gorging on Vitamin G foods. We may add that we regret this for his sake as well as on less unselfish grounds.
To be completely accurate, it should be said that there is not en-tire acceptance of the fact that Vitamin G will prevent pellagra.