History

History of Fish Oil

The history of fish oil is closely connected with cod liver oil, fishing communities of northern Europe and the eventual discovery of vitamins A and D. Long before scientists understood fatty acids or vitamins, fish and fish liver oils were used as food, lamp fuel, leather treatments and traditional remedies.

Traditional Uses of Cod Liver Oil

Cod fishing was economically important throughout northern Europe and the North Atlantic, and the liver was one of the useful by-products of the catch. Oil rendered from cod liver had domestic and commercial uses as well as a long history in traditional medicine.

By the late eighteenth and nineteenth centuries, European physicians were increasingly interested in cod liver oil as a treatment for several illnesses, particularly rickets, a childhood disease characterized by poor mineralization and deformation of developing bones.

Cod Liver Oil and Rickets

Rickets became especially common in crowded industrial cities of northern Europe. At the time, physicians did not yet know that inadequate vitamin D could cause the disease.

During the nineteenth century, cod liver oil was repeatedly reported to improve rickets. At the same time, other physicians observed that exposure to sunlight also appeared to prevent or improve the disease. It would take decades before these apparently separate observations were connected.

The Discovery of Vitamin D

The scientific story accelerated in the early twentieth century. Research by Edward Mellanby showed that experimental rickets in dogs could be prevented or treated with cod liver oil. Initially, researchers suspected that vitamin A might be responsible.

Elmer McCollum and colleagues later demonstrated that cod liver oil retained its ability to prevent rickets even after vitamin A activity had been destroyed. This led to the identification of a different fat-soluble nutritional factor, which became known as vitamin D.

At roughly the same period, researchers demonstrated that sunlight and ultraviolet radiation could also prevent or treat rickets. The connection eventually became clear: ultraviolet light enables vitamin D production in the skin, while cod liver oil supplies vitamin D through the diet.

Fish Oil in the Twentieth Century

Cod liver oil became a widely used nutritional supplement during the first half of the twentieth century. Generations of children in Europe and North America were given it as a source of vitamins A and D, particularly before routine vitamin D fortification of foods became widespread.

Food fortification and dedicated vitamin supplements eventually reduced the importance of cod liver oil as the principal way to prevent vitamin D deficiency.

From Vitamins to Omega-3 Fatty Acids

Interest in marine oils later shifted in another direction. During the twentieth century, scientists increasingly investigated the fatty-acid composition of fish and the biological roles of EPA and DHA.

This research transformed the meaning of “fish oil.” Cod liver oil remained a combined source of omega-3 fatty acids and vitamins A and D, while oils made from the tissues of fatty fish became widely marketed specifically as sources of EPA and DHA.

Today fish oil is available as conventional supplements, concentrated omega-3 products and regulated prescription medications used for particular medical purposes.

Fish Oil Today

Modern research has replaced many historical claims about fish oil with a more detailed picture. EPA and DHA are important nutrients, but fish oil is not a universal remedy. Its best-established uses and nutritional roles depend on the amount consumed, the source of the omega-3s and the health of the person using them.

You can read more about modern fish oil on the Fish Oil overview, or about its historically important relative on the Cod Liver Oil page.

For a detailed historical review of vitamin D, cod liver oil and rickets, see this historical review of rickets and vitamin D.