THE COMPARATIVE NUTRIENT VALUE OF COD LIVER OIL AND COD LIVER OIL CORDIALS [AS]
John Phillips Street, M.S.
Chemist, Connecticut Agricultural Experiment Station
NEW HAVEN, CONN.
For a long time cod liver oil has been recognized as an easily assimilable nutrient and reconstructive and of special value in wasting diseases. The unpalatability of the oil, however, has led to various devices to make it tasteless or to render it more acceptable to the stomach. Emulsions containing the oil in mixture with other substances were exploited, and doubtless served a useful purpose. The oil, however, but imperfectly concealed, was still disagreeable to many, and other preparations began to appear on the market, which claimed to retain the therapeutic virtues of cod liver oil without its disagreeable characteristics. This practice has been carried so far that now we find for sale cod liver oil preparations from which the oil has been removed in its entirety, and only the name remains. Certain of these products claim to “represent” the oil and to retain all its virtues; others are said to contain oil, while still others claim “all the valuable constituents” of the oil without the oil itself.
In the past, cod liver oil has been considered a food rather than a medicine, and its value attributed to the easily digestible and metabolizable oil it contains. This position, however, has been disputed. By some its therapeutic value has been attributed to the small amount of iodin present in the oil, but in recent years the suggestion has been made that its special potency depends on its peculiar fatty acids. In this connection the U. S. Dispensatory[145] says:
“Other oleaginous substances, certainly not less nutritious, have not been equally efficient, though taken in much larger quantities. If this be the true explanation, persons living chiefly on milk, which abounds in oil, or on fat pork, ought to show a special exemption from scrofulous complaints. The probability appears to us to be that, in consequence of some peculiar principle or principles it contains, it exercises a stimulant and alterative influence on the processes of assimilation and nutrition, thereby aiding in the production of healthy tissue.”
Indeed, Osborne and Mendel[146] have shown in their experiments on albino rats that by substituting cod liver oil for a portion of the lard in their standard diets, growth was resumed after failure on foods containing commercial lard alone as the source of fat. Similar results were secured with butter-fat and egg yolk fat.
In the light of the theories advanced for the therapeutic value of cod liver oil, and the results secured by Osborne and Mendel with the oil itself; it seemed a profitable study to examine some of the prominent “oilless” preparations on the market to determine whether or not the claims made for them as nutrients were justified. Certain of the so-called cod liver oil preparations are termed “extracts” of cod liver oil, and are not made from the oil, but from the cod livers instead. As has been well said,[147] “They are preparations, which, if honestly made, might be worthy of trial, but they are improperly called ‘extracts’ of cod liver oil, since they do not contain the fat, which is the active constituent of the oil, but the extractives from the liver, which may or may not possess therapeutic virtues. So far as we know, however, no satisfactory evidence is forthcoming to indicate that such extractives have any therapeutic value.”
It was with preparations of this class that our experiments were made. Four of the more extensively advertised brands were selected, as they represent rather distinct types of this class of products, as the following claims of their label will show: