The Man with a Fish on His Back: Science, Romance, and Repugnance in the Selling of Cod-Liver Oil

Early cod-liver advertisement

One of the earliest images of the man with a fish on his back appeared around 1884 on advertising trade cards. Image courtesy of the National Museum of American History Collections, Smithsonian Institution.

Scientific Medicine and “The Great Flesh Producer”

Cod-liver oil’s reputation as an effective treatment for “consumption,” a leading cause of death in the 19th century, led to its widespread popularity. A variety of diseases like scrofula, phthisis, tuberculosis, rickets, and rheumatism were understood to be manifestations of “consumption” or “wasting diseases.”

In 1882 Koch’s discovery of the tubercle bacillus, the “germ” that causes tuberculosis, launched a new era of scientific medicine. However, the new knowledge did not immediately yield effective new treatments, and the popularity of the old remedies remained unaffected. In their advertising Scott and Bowne recognized the role of microorganisms in disease, describing the cause of consumption as a growing germ that destroys the lungs much as a growing germ causes the “moulding of cheese.” As they explained, the germ itself is harmless until it finds some “smothered, starved, or tired, spot” within the body to grow. The strength of their product rested in its power to nourish the body and build up resistance to the germ. With Scott’s Emulsion, the thin and frail become plump and robust, and it was proudly proclaimed the “Great Flesh Producer.”

Pharmacological science in the 19th century focused on the identification and study of the “active principles” of the crude drugs. The isolation of plant alkaloids—such as morphine from opium and quinine from cinchona—provided medicine with substances of increased potency and known quantity that could be administered with more predictable results. Investigators sought the same success with cod-liver oil. In 1888 French chemists Armand Gautier and Luis Mourgues published an analysis of the active principles in light-brown cod-liver oil titled “Les alkaloides de l’huile de foie de morue.” Their findings echoed the earlier studies of de Jongh in their preference for the light-brown oils over the paler variety.

Although the medical community continued to debate the value of any “extract” of cod-liver oil, the commercial appeal and profitability of these products remained. Vinol, Wine of Cod Liver Oil, was one popular product, introduced in the late 1890s by Charles Kent and Company, Chemists, of New York City. In the company’s own words “Vinol is cod liver oil with out the oil.” The very fat that many still considered to be the essence of cod-liver oil’s therapeutic value had become the vile, useless, greasy part.

Scott and Bowne responded to the claims of the new popular extracts in their advertisements in the early 1900s:

Here are the Facts: You hear about the “active principles” of cod liver oil and are told that in certain wines, cordials and extracts of cod liver oil this principle is presented with the objectionable features left out. Nothing to it. The only active principle of cod liver oil is the whole oil.

As continued investigations failed to settle the controversy surrounding cod-liver oil’s “active principles,” the oil dropped out of favor with many doctors. The United States Dispensatory of 1918 summed up the situation thus: “Whether or not [the oil] acts simply as a foodstuff or whether it has some direct influence on the bodily metabolism, is open to dispute.”

The Oil and the Vitamin

Even as the 1918 Dispensatory edition was readied for publication, new research challenged its conclusions. In 1912 Polish-born biochemist Casimer Funk concluded that the lack of some essential nutrient caused certain diseases, such as beri-beri, pellagra, scurvy, and rickets. He coined the term vitamine (soon changed to vitamin) to describe these as yet unidentified substances.

Cod-liver oil played a central role in the nutritional research that uncovered the secrets of these mysterious vitamins. In experiments with rats at the University of Wisconsin in 1913, Elmer McCollum and Marguerite Davis proved the existence of an essential nutrient in cod-liver oil, dubbing it “fat-soluble A.” By 1922 McCollum identified another vitamin in cod-liver oil—the antiricketic “fat-soluble D.” Cod-liver oil was an important source of two “new” essential nutrients: vitamin A for growth and healthy eyes and vitamin D for the proper development of bones. Although recognized for a long time, rickets developed into a considerable health problem in the early 20th century, especially in the children of the urban poor.