Cod liver oil
Cod liver oil is an oil made from the livers of cod. It supplies omega-3 fats along with vitamins A and D.
Does it prevent winter infections?
In a Norwegian trial, 34,601 adults received 5 mL of cod liver oil or placebo daily for up to six months. The oil did not reduce COVID-19, serious COVID-19 or other acute respiratory infections. Most participants tested in a subgroup already had adequate vitamin D, so this was not a trial of treating severe deficiency. 1
The large Norwegian trial found no protection against acute respiratory infections. 1
What about cholesterol?
A small clinical lead comes from a 30-day trial in people with high cholesterol: cod liver oil added to rosuvastatin lowered total and LDL cholesterol more than the drug plus placebo. Triglycerides and HDL did not differ between groups. The single-center study analyzed 550 completers from 600 recruits; it neither tested oil alone nor established fewer heart attacks. 2
A short adjunct trial improved LDL, without testing oil alone or cardiovascular events. 2
Effects by health goal
Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.
Essential Health1 effect
Longevity1 effect
No study is linked to this rating.
Immune Support1 effect
No study is linked to this rating.
Bone & Joint1 effect
No study is linked to this rating.
Cardiovascular1 effect
No study is linked to this rating.
Cognition2 effects
No study is linked to this rating.
Organ Function1 effect
No study is linked to this rating.
Other effects1 effect
No study is linked to this rating.
All studies
3 publications are linked to Cod liver oil, newest first.