Kepler cod liver oil with malt extract, late 19th early 20th century.
© Science Museum / Science & Society Picture Library
Bottle of cod liver oil shown in a counter top display case. Part of a shop fitting from The Old Pharmacy, Hexham. Cod liver oil is obtained from the fresh liver of the cod fish and then refined. The oil is a valuable source of vitamins A and D. A deficiency of vitamin A can cause night blindness, an inability to see in dim light, which is a common affliction for children in poor countries. Vitamin D deficiency can cause rickets, another common health problem in the developing world. Cod liver oil is also now believed to offer protection against heart disease because of its high content of unsaturated fatty acids.