Preliminary data suggest that cod liver oil users have lower risk of getting COVID-19
But is it because cod liver oil protects against COVID-19, or do those who take a daily dose have other lifestyle factors that lower their risk of infection?
Norwegian researchers are about to embark on one of the country’s largest clinical trials in order to answer this question, according to a press release from Oslo University Hospital.
“Preliminary data from our ongoing COVID-19 study, Koronastudien, suggest that cod liver oil users may have a reduced risk of COVID-19 and a lower risk of severe disease outcomes if they are infected”, says Arne Søraas, in the press release. He is a physician-scientist at the Department of Microbiology at Oslo University Hospital.
“This finding supports existing literature on omega-3 fatty acids, and vitamin D on respiratory tract infections and COVID-19”, Søraas says.
Cod liver oil is rich in vitamin D and omega-3 fatty acids. Cod liver oil is among the few natural sources of vitamin D in the nordic diet, writes Store Norske Leksikon. It has traditionally been recommended to particularly take during the winter when a lack of sun halts the body's own production of vitamin D.
However, the researchers cannot know from the Norwegian COVID-19 study (Koronastudien) whether the difference lies in cod liver oil, or other aspects of the lives of cod liver oil users.
To answer this question, a randomized study needs to be done.
Large randomized trial
The study, which is already recruiting participants, aims to include at least 70 000 people.
Half of them will take a daily dose of cod liver oil, the other half will be given a placebo product. As it goes in randomized studies, participants will not know if they are taking the real or the fake stuff.
The study is partially funded by the company Orkla, who produce the brand Möllers Cod Liver Oil. This is also the oil which will be used in the project.
“We were contacted by Oslo University Hospital and saw this as an opportunity to contribute to the fight against the pandemic while also gaining new insight into the positive effects of taking cod liver oil”, Gunnhild Aarstad says in the press release. She is head of Research, Development and Innovation at Orkla Health.
The study will run from November until April next year and will also look for the effect of cod liver oil on other viral diseases such as seasonal flu and ordinary colds.
Read more about the Norwegian COVID-19 study in this article: Here’s how researchers will find out if Norway’s efforts to fight the corona virus work
Important for people with darker skin
Saumia Shankar, a doctor at Oslo University Hospital, said to the Norwegian national broadcaster NRK that the study could prove important for people with darker skin.
“The target group is those who have a vitamin D deficiency. We know that people with darker skin more often have such a deficiency. So it’s very important that the study recruites as many people with a vitamin D deficiency, or with dark skin, so we can see the effects more clearly”, she says.