We have recently received enquiries about several internet newsletters that have made disparaging remarks about cod liver oil. As the Weston A. Price Foundation recommends the use of cod liver oil as a nutrient-dense food, we thought it would be good to address the concerns that have been expressed, clarify our position and point out the science-based research that we have compiled on this subject.
Critics of cod liver oil have focused on three concerns:
1. Cod liver oil contains dangerous amounts of mercury and dioxins.
2. Cod liver oil contains dangerous amounts of vitamin A.
3. The vitamin A in cod liver oil interferes with the body’s assimilation of vitamin D.
MERCURY AND DIOXINS IN COD LIVER OIL
Cod liver oil is probably one of the cleanest foods in the food supply. All cod liver oil goes through a complete filtering process, and repeated testing has shown that the amounts of mercury and PCBs in cod liver oil are undetectable. See the following link for an article on cod liver oil processing:
Even without modern processing, mercury in cod liver oil is not a concern because mercury accumulates in the protein portion of fish, not in the oil.
In addition, the vitamin A in cod liver oil is our best protection against dioxins.
See our article on this subject at http://www.westonaprice.org/envtoxins/dioxins.html. To quote from the article,
“. . . vitamin A appears to play a unique role in protecting against the toxicity of dioxins, and has some protective effects that other antioxidants do not have. A large part of vitamin A’s protective role is attributable to its antioxidant effect.”
VITAMIN A IN COD LIVER OIL
The claim that vitamin A in cod liver oil is toxic just doesn’t make sense in the context of traditional diets, which were very rich in vitamin A from liver, organ meats, seafood and the fats of grass-fed animals. The crux of Dr. Price’s research is that the diets of healthy primitive peoples contain about ten times more vitamin A than modern diets. That is why we recommend cod liver oil as an excellent food source of vitamin A.
Over the years, the Weston A. Price Foundation has compiled extensive evidence showing that natural vitamin A in foods such as cod liver oil is not toxic EXCEPT in cases where vitamin D is deficient. That is why we recommend only certain brands of cod liver oil. It is important to AVOID cod liver oil that contains low levels of vitamin D in relationship to vitamin A; the ratio of A to D in cod liver oil should be at least 10 to 1 – unfortunately, in some commercial brands of cod liver oil the ratio is as low as 100 to 1.
For general information on cod liver oil and recommended brands, see
For the latest research on vitamin A see:
For the latest research on vitamin D see:
For an article on vitamin A for pregnant women, see:
The US Recommended Daily Allowance for vitamin A is far too low and has led to
widespread suffering from vitamin A deficiency. It is ironic that one of the main critics of cod liver oil, who refers to the US RDA when he claims that vitamin A is toxic, has been working for years to dispel the notion that vitamin D is toxic and to convince the US government to raise the RDA for vitamin D.
VITAMIN A AND VITAMIN D INTERACTIONS
The articles cited above show that vitamins A and D work synergistically, not antagonistically; if you take large amounts of vitamin A without vitamin D, you are likely to develop symptoms of vitamin D deficiency. Likewise, if you take large amounts of vitamin D without vitamin A, you are likely to develop symptoms of vitamin A deficiency.
The critics of cod liver oil seem to have very little understanding of how these vitamins work together. In fairness, very little study has been done on the interaction of A and D, although there is enough to show that A and D work synergystically. Recent research from Spain indicates that vitamin A is necessary for both vitamin D binding and vitamin D release to receptor sites. We will be reporting on this work in an upcoming article in Wise Traditions.
Once again, it is important to realize that traditional diets were rich in both A
and D and that A and D have a myriad of uses in the body. Traditional peoples always had plentiful amounts of both A and D in their diets.
THE COD LIVER OIL PUBLIC HEALTH INITIATIVE
During the first half of the century, cod liver oil was the focus of a worldwide health initiative. Parents were urged to give cod liver oil to their children by doctors, by government officials, by teachers and principals in schools, and even by their ministers in churches. A large portion of adults in America born before the Second World War received cod liver oil as children and this practice contributed to a high level of health, intelligence and physical development in those lucky enough to receive it. In Europe in many countries, children received a daily ration of cod liver oil, especially during the war years. In the UK, for example, the government issued cod liver oil to all growing children until the early 1950s.
What has led to the demise of this obviously beneficial practice? Cod liver oil is a food; it can’t be patented, it can’t be created in a laboratory; it can’t create millions for the drug companies. So interest in this wonderful superfood has naturally waned. But if you are basing your dietary habits on the principles of healthy nutritional diets, don’t hesitate to include cod liver oil-our recommended brands of cod liver oil–as a healthy and natural food source of critical vitamins so lacking in modern diets.
We will be publishing more on cod liver oil in an upcoming issue of Wise Traditions, so stay tuned!
Ted Kehn says
Please send me the name of recommended sources of cod liver oil.