Once considered an esssential health food, cod liver oil has fallen out of favor in recent years. Is the drop in popularity warranted, or have we simply forgotten about one of nature's most beneficial gifts?

If you thought grandma was wrong about the health benefits of a daily dose of CLO, think again.

But with the evidence mounting that cod liver oil may be effective in the treatment or prevention of ailments as diverse as arthritis, gastrointestinal disorders, diabetes, alzheimer's - and according to some research even cancer - what is it that stops so many of us cold when we think about swallowing the seemingly miraculous stuff?

We've compiled some of the more frequent reservations that we hear whenever the subject of CLA comes up.

Myth #1: You already get all the beneficial essential fatty acids (EFAs) you need through flax seed, flax seed oil, and other foods

You probably don't.

Flax seed oil certainly does contain Omega 3 fatty acids. But plant based sources of omega 3 are of the form of alpha-linolenic acid (ALA) which the body can only convert in very small amounts to the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that provide the real benefits of essential fatty acids.

This is not to say that flax seed oil or other plant based oils are necessarily bad. They aren't. However, people generally take these products under the misguided impression that by doing so they are getting the full benefits of heart and brain healthy EFAs. They aren't.

The oils and fats from cold water fish do not require any conversion to EPA or DHA -- they are already in these beneficial forms, and are present in abundance.

Myth #2: All Oils Are Created Equally

Unfortunately, this is not the case. Historically, supplement companies have been in the practice of removing the natural vitamin D from their fish oil products, and adding back in synthetic vitamin D and/or synthetic vitamin A in controlled amounts.

These synthetic versions have demonstrated themselves as not only not as effective as the naturally occurring vitamins A and D, but it is becoming increasingly clear that they are unhealthy to consume. Many of the criticisms and cautions regarding cold liver oil in recent years have been reactions to the unfortunate lack of quality and over-processing of much of the CLO on the market.

It is also important that there be an adequate amount of vitamin D to vitamin A in your cod liver oil. It is all too easy to find cod liver oil that has 100 times as much vitamin A as vitamin D, when the desirable ratio is closer to 10 to 1 of vitamin A to vitamin D. Some notable figures in the health community have withdrawn their former recommendations for CLO consumption for this reason, but that is an overreaction. There remain quality manufacturers of cod liver oil, and by supporting those manufacturers who are attentive to maintaining the healthy qualities of their product hopefully those who are currently pumping out the inferior products will be motivated to change their ways.

Myth #3: Cod Liver Oil May Contain Dangerous Amounts of Vitamin A and D

It has been a long battle, but the good guys have won. For years, based largely on the results of poorly conducted studies and the use of toxic synthetics, there were warnings about exceeding the shockingly low RDA of 400 IU of vitamin D. But recently even the least progressive medical circles have conceeded that the RDA has been too low for too long and that vitamin D deficiency in the west is epidemic. Physicians and nutritionists are now recommended supplemental vitamin D in amounts that would have been thought shocking only several years ago, and we are beginning to see the true damage and consequences that the unnecessary cautions regarding oral vitamin D intake have caused.

Unfortunately, newer understandings of the interplay between vitamins A and D have not yet gained the traction of our recent re-discovery of the crucial importance of vitamin D, and some fear remains about potential vitamin A toxicity. While this has often been attributed to a general lack of understanding regarding the stark differences between supplemental synthetic retinol as used in fortification and food sourced retinol, it is not clear from the research that the form of vitamin A is necessary to blame. What is becoming clear, however, is that vitamin D itself is protective against vitamin A toxicity and that we should be concerned less with the amount of retinol consumed and more with the relative ratio of vitamin D to vitamin A in consumption. This alone is a strong reason to avoid overly tampered with oils and also a strong reason to consume a naturally balanced CLO.

Myth #4: It Is Dangerous To Take CLA During Pregnancy

Myth #5: Fish Oils Of Any Type Are Equivalent

This is most certainly not the case, particularly in regards to vitamin D. While fish oils in general are good sources of EPA and DHA to varying degrees, cod liver oil is the best oil source of vitamin D. Particularly during the winter months, it makes sense to consume cod liver oil instead of salmon, krill or other oils.

Myth #6: Cod liver oils and fish oils in general aren't safe to consume because of mercury and PCB contamination of fish

It is always advisable when considering any fish oil product to be sure that the manufacturer regularly tests for contamination. Often the product label and the manufacturer's website will reveal their testing policy. Don't be afraid to ask when in doubt. You want a product that has tested as free of any detectable levels of mercury, cadmium, PCBs, and other contaminants. You may take some comfort in knowing that all cod liver oil imported into the US must pass testing to be free of all of these contaminants.

Mercury in particular, due to its water solubility, is more likely to concentrate in the flesh of the fish, rather than in the oils.

"Not only does cod liver oil reduce pain and inflammation in the joints of people with osteoarthritis but we now know it also turns off the enzymes responsible for destroying cartilage."
- Fergus Logan, Arthritis Research Campaign

Myth #7: Cod Liver Oil Tastes Awful!

If you grew up taking cod liver oil by the spoonful, you are probably have memories of a rather unpleasant taste.

But did you know that the "awful" taste was most often due to rancidity resulting from poor manufacture processes? It's true.

And while it can be disturbing to think that you were once swallowing rancid oil, the good news is that such practices are no longer tolerated in the industry. Modern processing and preservation means that there is no longer an excuse for rancid oil to be sold to the public. You'd be surprised by the difference! Add to that the availability of gel capsules instead of liquid, and even naturally flavoured varieties (lemon, cinammon, etc..) and there is simply no reason to fear the taste of this beneficial supplement any longer.

Recommended additional reading:

• Weston A. Price Foundation: Cod Liver Oil
• Weston A. Price Foundation: Cod Liver Oil Clarifications
• Weston A. Price Foundation: CLO information update - Dec. 2008
• Cheeslave: Why Fermented Cod Liver Oil?

Recommended listening:

• Chris Masterjohn on the Science of Cod Liver Oil
• Patrick Timpone interviews Dave Wetzel, founder of greenpasture.org, about high vitamin butter oil and fermented cod liver oil

Archived videos:

• Dr. Kendra Pearsall discusses why you need to take your cod liver oil