Q: My neighbor swears by cod liver oil and says I should try it. Could it improve my health?
Cod liver oil is a type of fish oil and is a good source of the fat-soluble vitamins A and D. Like other types of fish oil, it may contain Omega-3 essential fatty acids, helping to ease stiff joints and minor muscle aches.
Cod liver oil didn’t start out as a medicine. A byproduct of the Norwegian fishing industry, cod liver oil was initially used to soften leather and as a hoof dressing for horses.
In the 1800s, German physicians found that when taken internally, cod liver oil could cure children of rickets, a common disease back then that caused severe bone deformities. Swallowing a dose of cod liver oil every day also seemed to help relieve joint aches, gout, and “obstinate constipation.”
The United States Pharmacopeia (USP), describes Cod Liver Oil, USP as “a thin, oily liquid with a characteristic, slightly fishy odor and a definitely fishy taste” made by “steaming the livers of the Atlantic cod, then straining the oil that rises to the top of the vat or kettle.” The official formulation of Cod Liver Oil, USP, contains 3 active ingredients: vitamin A, vitamin D, and Omega-3 essential fatty acids.
By 1851, cod liver oil was declared “one of the most esteemed remedies currently available.” Doctors strongly recommended it, but children HATED taking it. Suggestions on how to improve the “fishy” taste of cod liver oil began to show up in medical and pharmacy references of that period.
For example, the 19th edition of The United States Dispensary published in 1907 contains this advice about Cod Liver Oil, USP: “It may be taken alone or mixed with some vehicle calculated to conceal its taste and prevent nausea. Peppermint oil has been found to be helpful.”
Another suggestion mentioned in the dispensary is to “chew a small piece of orange peel before and after taking cod liver oil.” That should be pretty effective in masking the taste of fish oil, or just about anything else!
Cod liver oil may improve your health if your diet is low in vitamin D or vitamin A. Vitamin D is essential to incorporate minerals such as calcium into new bone tissue. A deficiency of vitamin D creates weak bones causing deformed bones in children, a disease called rickets.
Without enough vitamin D, the new bone formed by a growing child is not rigid enough to support body weight, creating crooked bones and skeletal deformities. In contrast, in adults, vitamin D deficiency causes weak bones, called osteomalacia. Vitamin A deficiency can also cause growth retardation, night blindness, and increased susceptibility to infections.
The official recipe of cod liver oil listed in the United States Pharmacopeia (USP) is Cod Liver Oil, USP. It contains 850 USP units of Vitamin A, 85 USP units of Vitamin D, and approximately 1 gram of Omega-3 essential fatty acids in each tasty teaspoonful, a concentration similar to that found in salmon oil.
The dose of cod liver oil recommended in the USP is one teaspoonful 3-4 times daily for children and one tablespoonful (3 teaspoonfuls, or 15ml) 3-4 times a day for adults. Other formulations of cod liver oil besides the standard version contain extra vitamin A or D added by the manufacturer.
The amount of Omega-3 fatty acids in cod liver oil varies, with formulas using Atlantic cod having the most and those from Pacific cod having little to none. Interestingly, cod liver oil was considered helpful in chronic rheumatism (joint or muscle aches). One cod liver oil product contains nearly the same concentration of Omega-3 fatty acids found in today’s popular salmon oil supplements.
To reduce the prevalence of rickets in its children, the United States began fortifying milk in the 1930s with added vitamins A and D.
Every 8-ounce serving of cow’s milk has 100 international units of Vitamin D, 25% of its current FDA recommendation. 150 units of vitamin A, which is 10% of its recommended daily intake. Today’s ready to eat cereals are also fortified with 10% of the recommended daily intake of both vitamins A and D. Rickets is now very rare in the United States.
Cod liver oil was one of the first effective vitamin supplements available, but thankfully there are more palatable options today to prevent vitamin A and D deficiency. One tablet of either Centrum Silver® or Flintstones® chewable is today’s modern, and much tastier equivalent.
