Green Pastures Fermented Cod Liver Oil is a great immune booster. Many of the great historical cultures had one sacred food which they relied on to ensure strong mind, body, and spirit; fermented fish/fish liver oil. The Might Roman Soldier was given a daily ration of fermented fish oil. The Stoic Scandinavian Viking had a drum of fermenting cod livers outside the door of his home. Grandma always had a bottle of cod liver oil in the back cupboard.