Could cod liver oil improve your health?

Q: My neighbor swears by cod liver oil and says I should try it. Could it improve my health?

Taking cod liver oil may help if you are deficient in vitamin A or vitamin D because it is an excellent source of these two fat-soluble vitamins.

According to the United States Pharmacopeia (USP), the official recipe for Cod Liver Oil is "a thin, oily liquid with a characteristic, slightly fishy odor and a definitely fishy taste." It was made by "steaming the livers of the Atlantic cod, then straining the oil that rises to the top of the vat or kettle."

Cod liver oil didn’t start out as a medicine. A byproduct of the Norwegian fishing industry, cod liver oil was initially applied to horse hooves as a conditioner and rubbed into leather goods to soften them.

In the 1800s, rickets was a common childhood disease that caused severe bone deformities. When German physicians discovered that they could cure rickets by giving children cod liver oil internally, it caused a sensation. In older people, swallowing cod liver oil helped relieve joint aches, painful gout, and "obstinate constipation."

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 improving the “fishy” taste of cod liver oil began to show up in the medical and pharmacy references of that period.

The 19th edition of The United States Dispensary, published in 1907, contains this advice about cod liver oil: “It may be taken alone or mixed with some vehicle calculated to conceal its taste and obviate nausea. Peppermint oil has been found to be helpful.”

Another suggestion was to “chew a small piece of orange peel before and after taking the medicine.” This should be effective in masking the taste of fish oil or just about anything else!

Like other types of fish oil like salmon oil, taking cod liver oil can help ease stiff joints and minor muscle aches.

Cod liver oil may improve your health if your diet is low in either vitamin A or D. Your body requires vitamin D to incorporate calcium into your new bone tissue. A severe nutritional deficiency of vitamin D causes rickets in children and osteomalacia in adults.

New bone is not rigid enough to support the body weight of a growing child without enough vitamin D, creating crooked bones and skeletal deformities. In contrast, in adults, vitamin D deficiency causes weak bones, called osteomalacia. Vitamin A deficiency can cause growth retardation, night blindness, and increased susceptibility to infections.

The official recipe for cod liver oil listed in the United States Pharmacopia (USP) is Cod Liver Oil, USP. Each teaspoonful contains 850 USP units of Vitamin A and 85 USP units of Vitamin D plus approximately 1 gram of Omega-3 essential fatty acids, a concentration similar to that found in salmon oil.

The dose of cod liver oil recommended back in the day was one teaspoonful 3-4 times daily for children and one tablespoonful (3 teaspoonfuls, or 15ml) 3-4 times a day for adults.

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). At least one old-time cod liver oil product contained nearly the same concentration of Omega-3 fatty acids as found in today's salmon oil supplements.

In the 1930s, the United States began adding vitamin A and D to milk to reduce the high prevalence of rickets seen in children. Every 8 ounce serving of cow’s milk has 25% of the recommended daily intake of vitamin D and 10% of the recommended daily intake of vitamin A. Most ready-to-eat cereals in the US are fortified with 10% of the recommended daily intake of vitamin A and D. Rickets is now very rare in the United States.

Will taking cod liver oil improve your health? It may help you get more Vitamin D and Omega 3 fatty acids. It also contains high concentrations of vitamin A, which you may not need.

Instead of an oily, fishy-smelling liquid, today’s cod liver oil is available as capsules, similar to fish oil. There are many cod liver oil formulas available in addition to the original USP version. Refer to the vitamins A, D, and Omega 3 fatty acid content listed on each label for best results.


Dr. Louise Achey, Doctor of Pharmacy, is a 40-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog ®2021 Louise Achey



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