Medically reviewed by Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT — Written by Leslie Vandever 
Updated on August 6, 2019

A brief history of cod liver oil

In the 19th and early 20th centuries, children were often fed a spoonful of cod liver oil, a practice rooted in hundreds of years of folk medicine.

As medical science later confirmed, deriving important nutrients from certain foods is a useful complementary treatment method for certain conditions.

Rickets, a disease caused by a lack of vitamin D in the body, was common prior to the mid-1950s. The disease affected very young children, softening and deforming their bones. They’d outgrow it within a few years. By then, however, permanent damage had already occurred.

Cod liver oil was traditionally used to treat rickets, though scientific evidence that the oil’s high vitamin D content made this treatment effective wasn’t available until the 1930s.

In addition to vitamin D, cod liver oil is also rich in vitamin A, making it very good for the bones, teeth, and eyes. It’s rich in omega-3 fatty acids as well.

Toward the end of the 20th century, researchers began studying fish oil. Unlike cod liver oil, fish oil doesn’t contain vitamins A and D. However, it’s much richer in omega-3 fatty acids than its counterpart. Omega-3s are excellent for heart health — and, as it turns out, for arthritis.

EPA and DHA

The two types of omega-3 fatty acids found in fish oil are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

EPA and DHA can reduce inflammation, which causes swelling and pain. ResearchTrusted Source has indicated that both acids might suppress the body’s immune system. However, a 2016 studyTrusted Source suggests that DHA might enhance immune function instead. DHA is more effective at reducing inflammation than EPA, but both have a role.

All of these effects makes fish oil potentially beneficial for people with arthritis.

EPA and DHA come with other health benefits: They can help prevent heart attacks by making it harder for blood to clot. They help lower blood triglyceride levels and blood pressure. As well, EPA taken with statin medication is more effective in reducing the inflammation of arteriosclerosis than medication alone.