Vitamins — A Review of Definitions and Principles

In any new science a certain time must elapse before a sufficient background of facts can develop to permit a logical appraisal of the situation, which appraisal is indispensable before any basic principles can be laid down.

Premature conclusions are often incorrect. Persons of some scientific education in other fields have been prone to consider themselves competent to make arbitrary pronouncements that sound reasonable on their face, but which on consideration are found to be totally at variance with the facts.

Probably the most outstanding example of such witless comment is the statement that “any well balanced diet” will maintain health without the need of considering the vitamin intake.

The joker here is that what has always been considered a well balanced diet may be, and usually is, quite inadequate in view of our newer knowledge of nutrition; and the more we learn, the more inadequate it appears.

The new dictionaries are agreed on the following definition of a vitamin:

“One of a class of substances of unknown composition, existing in minute quantity in natural foods and necessary to normal nutrition and growth, absence of which from the diet produces deficiency diseases, such as beriberi, scurvy and rachitis.”

While considerable progress has been made on the investigation of the composition and chemical nature of the various vitamins, it is quite important that here, too, we avoid jumping at conclusions. Many of the past conclusions have proven faulty. The real test of a vitamin to its ability to cure deficiency disease.

Two significant facts in particular are becoming apparent, as follows:

1. Chemical purification of a vitamin principle may render It ineffective, known to be true of “E,”1 “G”2 and “B.”3
2. To produce the same vitamin effect in different species may require entirely different principles (chemically considered). (See appended reference4 regarding this point in respect to Vitamin D, and reference5 in respect to Vitamin C.)

It will be at once obvious that an assay of vitamins to be used for human therapy by means of animal test is of doubtful value until it is determined what relation there may exist between the effectiveness of the product under examination when used for the test animal and the human. Even assuming that this relation may be a constant coefficient (speaking now as regards Fact No. 2), the possibility remains that there may be associated or related principles in the animal economy differing from human metabolism that can alter the results in view of Fact No. 1. It is these considerations that have rendered it impossible for the clinician to depend upon unit content as determined by animal assay as an index of therapeutic merit.

With respect to Vitamin A, the U.S.P. X authorized its estimation in terms of carotene because of the naive theory that carotene was convertible at will into Vitamin A in the human or animal organism. This was discontinued in the U.S.P. XI, a direct assay with test animals being required in which a comparison is made between the test sample and a standard reference cod liver oil. (No form of chemically pure Vitamin A has as yet been made.) This also has been the approved method of making Vitamin D assays according to both U.S.P. X and U.S.P. XI.

Such a test does just one thing. It standardizes the tested oil in terms of the reference oil with respect to its effect on the test animal. But suppose neither contained the principle that was necessary to perform as Vitamin D in some species other than the rat, which was used as a test animal. They would be of no value in treating rickets in such an animal. As a matter of fact, the chicken must have a different substance to receive the Vitamin D effect than is required in the rat,6 and we have precisely the situation described above. Highly concentrated forms of Vitamin D (as determined by rat tests) have been found totally valueless (in fact, poisonous) to the chicken as a cure for rickets.

As to the applicability of the rat test to the human, we remain pretty much in the dark. There is evidence to show, however, that babies are more like the chicken in their reactions to the rat vitamin.7

Primarily a vitamin is a dietary essential that must be present to prevent some well defined deficiency disease or other.

If various different species become afflicted with the same disease by reason of a deficiency of chemically different dietary principles that occur in such small amounts that it is difficult to find them, it becomes necessary, in speaking of a vitamin, to also specify the species for which it is effective.

Upon reflection the reasonableness of these facts becomes more apparent. Each species has its own peculiar tissue chemistry–its own fatty acids, proteins and carbohydrates. The most suitable food for each species differs in the same manner–the cow can digest cellulose and form stearic acid; the pig can better handle cornstarch as carbohydrate, and forms from it mainly oleic acid. To assume that the same vitamin structures (molecularly speaking) serve all species in the same manner would, therefore, violate a primary principle of nutrition and metabolism.

Immunology has positively demonstrated the specific nature of the proteins of each species and has shown us how the chemical variation in blood proteins can be used to identify a blood stain as to its source, whether human or animal, and, if animal, what species. Many a murderer has been incarcerated, and, no doubt, some have suffered capital punishment on the acceptance of our courts of Justice of such distinguishing tests. (I recall one case where the only evidence against a suspect was a tiny blood stain on a hunting knife, he claiming it to be rabbit blood. The laboratory technician found it to be human blood by immunological test, and after receiving a life sentence, the murderer confessed.)

It is such a reaction that causes a reversal of effect (antihormone reaction) when some hormone products are administered to a species other than the one that produced the produced hormone. Some time is required for the reaction to change from the positive to the negative, the hormone injections gradually losing their effect, finally having an opposite action.8 Where the hormone administered is obtained from the same species as the animal to which it is administered, the normal effect continues undiminished when dosage is extended over a long period. (The hormone in question must be protein in nature to cause this immunological reaction.)

Because of this specific nature of hormones of each species, and because vitamins are to be considered the chemical precursors of the hormones, it is a reasonable conclusion to assume that there is a chemical difference in the vitamin principles that act most favorably as foods for the different species. The appended references show experimental evidence supporting this inference.

 

NOTE: More recent work has shown that Vitamin G probably is specific in nature for the three

species so far investigated–the rat, chick and human. (See references in the Journal of Biological Chemistry, 114:1, May 1936, by Lepkovsky and Jukes, pages 109-116; Jukes and Lepkovsky, pages 117-121.)

 

Editor’s note: for References, please access the pdf.