Cod Liver Oil As A Source Of Omega 3 Fatty Acids

Some people take cod liver oil instead of fish oil as their source of omega 3 fatty acids, in order to gain the benefits of omega 3 oils.

Is there a difference between the two? And is there an advantage of taking one over the other?

Let’s firstly have a look at:

The difference between fish oil and cod liver oil

Cod liver oil is traditionally produced from cod livers, while fish oil is produced from tissues of fatty fish. Cod liver oil has a midly fishy taste, and hence many companies now add lemon or citrus to make the taste more pleasant.

Both fish and cod liver oils are sources of omega 3 fatty acids (EPA and DHA).

But the main difference in composition between cod liver oil and fish oil is that cod liver oil has higher levels of vitamin A and D, two fat soluble vitamins. This has led to some concern that there may be a risk of taking too much vitamin A or D while on cod liver oil, especially for pregnant women.

Cod liver oil and vitamin D

Reports of overdoses on either vitamin are not common, but there is a strategy that you may want to use to decrease the remote possibility of excess vitamin D intake. Since vitamin D is produced by the body in greater amounts when exposed to sunlight, some people take cod liver oil in the winter months, and switch to fish oil in the summer months to reduce this possibility of excessive vitamin D.

Cod liver oil and vitamin A

With respect to vitamin A, an overdose of vitamin A can be a problem especially during early pregnancy.

A study in the New England Journal of Medicine looked at the issue of vitamin A during pregnancy. The study stated that above 10,000 IU per day of supplemental vitamin A (retinol), there was an increasing risk of birth defects. The timing was also a factor: “The increased frequency of defects was concentrated among the babies born to women who had consumed high levels of vitamin A before the seventh week of gestation.”[1]

Interestingly, there was a study in Norway published in 2003 in the journal Paediatrics, looking at the effect of cod liver oil supplementation during pregnancy and breast feeding, on the IQ of their children at 4 years of age.

Pregnant women, from 18 weeks of pregnancy until 3 months after delivery were recruited, and took either 10ml of cod liver oil per day, or, as the control group 10ml of corn oil per day.

Note that this study looked at the effect of cod liver oil from the middle of the second trimester, and avoided the risky period of the first trimester.

The cod liver oil contained 1183 mg/10 mL of DHA, 803 mg/10 mL of EPA (the marine sources of omega 3 fatty acids) while the corn oil contained 4747 mg/10 mL linoleic acid (omega 6 fatty acid) and 92 mg/10 mL alpha-linolenic acid (the plant source of omega 3 fatty acids). The amount of fat-soluble vitamins was identical in the 2 oils.

It was found that there was a significant correlation between mother’s intake of cod liver oil and the IQ performance of children at age 4.[2]

Omega 3 oils as brain food is a theme that is increasingly being found in studies, in all its functions, including mood and risk of depression as well as IQ.

To read more, see this page on iceland omega 3.

References:

• 1. Rothman KJ, Moore LL, et al. New England Journal Of Medicine. Teratogenicity of High Vitamin A Intake. Volume 333:1369-1373. November 23, 1995.

• 2. Helland IB, Smith L, et al. Maternal supplementation with very-long-chain n-3 fatty acids during pregnancy and lactation augments children's IQ at 4 years of age. Pediatrics. 2003 Jan;111(1):e39-44.