Cod liver oil is occasionally used as a supplement to support skin health in conditions like psoriasis due to its rich content of omega-3 fatty acids (EPA and DHA) and vitamins A and D. There is some scientific rationale for its use: omega-3 fatty acids have anti-inflammatory properties, and several studies have investigated their potential benefit in psoriasis, an inflammatory skin disease. A few small clinical trials and case reports from the 1980s and 1990s suggested that omega-3 supplementation (including fish oil, sometimes cod liver oil) might reduce psoriasis severity, but results have been inconsistent and generally modest. A 2014 systematic review concluded that while some benefit is possible, the quality of evidence is low, and effects are not dramatic.

The vitamins in cod liver oil, especially vitamin D, are also of interest since vitamin D analogues are used topically in psoriasis treatment. However, oral vitamin D from cod liver oil has not been shown conclusively to improve psoriasis. Overall, the use of cod liver oil in psoriasis has some scientific basis, but evidence is limited, and it is not considered a primary or strongly supported therapy. More robust, modern clinical studies are needed to clarify its role.