In November of 2008, Dr. Cannell of the Vitamin D Council published a commentary in the journal Annals of Otology, Rhinology & Laryngology attacking cod liver oil because of its high vitamin A content, claiming that vitamin A intakes above the most minimal levels would increase mortality rates, increase vulnerability to infections, cause osteoporosis, and antagonize the beneficial effects of vitamin D. Sixteen scientists signed on to the paper as co-authors. In response, Wise Traditions published my article “The Cod Liver Oil Debate,” in the Spring of 2009, which defended cod liver oil as an important and balanced source of the fat-soluble vitamins and essential fatty acids. The following November, I expanded on this article in my lecture, “Cod Liver Oil: Our Number One Superfood” at the Foundation’s annual conference.
We were not the only ones who responded.
In January 2010, Michael F. Hollick, MD PhD, a vitamin D researcher whose work I have cited in previous articles, Linda Linday, a medical doctor whose cod liver oil study formed the starting point for Cannell’s 2008 commentary, and several other colleagues, even including one researcher from the NIH, made a direct response to Dr. Cannell and his colleaugues in the pages of the same journal. What’s more, they even credited the Weston A. Price Foundation for raising concern about the balance between vitamins A and D!
“Cod liver oil,” they wrote, “available without a prescription for hundreds of years, is a valuable source of vitamins A and D, as well as long-chain omega-3 fatty acids, all of which may be important in the prevention of respiratory tract illnesses in children. In many populations around the world, cod liver oil continues to be a valuable source of these important nutrients. The across-the-board dismissal of cod liver oil as a supplement advocated by [Cannell and colleagues] ignores this reality.”
The authors pointed out that in Dr. Linday’s randomized, controlled trials, cod liver oil supplementation cut doctor’s visits for upper respiratory infections between one-third and one-half. Cannell’s paper called this “less than robust,” but most of us would consider such a reduction meaningful, especially if it could mean we could get sick half as often by taking cod liver oil! The authors, moreover, argued that retinol from animal foods is a more reliable source of vitamin A than carotenes from plant foods since there is such wide variation in people’s ability to convert carotenes to vitamin A – an argument that has crossed the pages of Wise Traditions many times in the past.
But now to the exciting part.
The authors devoted a section of their paper to the ideal ratio of vitamin A to D. “In the responses to [Cannell and colleagues] from the on-line supplement and nutrition newsletter communities,” they wrote, “the issue of the proper ratio of vitamin A to vitamin D emerged as a major concern.” They gave three references, including one to the Weston A. Price Foundation’s “Cod Liver Oil Update” from December, 2008.
In fact, the importance of balance between vitamins A and D was raised in the pages of Wise Traditions even earlier than 2008. In the spring of 2006, I raised the issue in my article “Vitamin A on Trial: Does Vitamin A Cause Osteoporosis?” when I argued that vitamin A only contributes to osteoporosis when vitamin D levels are deficient or when the ratio of vitamin A to D is massively out of balance. The following fall, I raised the issue again in my article “From Seafood to Sunshine: A New Understanding of Vitamin D Toxicity” where I presented research showing that vitamin A protects against vitamin D toxicity and introduced the possibility that vitamins A, D, and K may be cooperative factors that should all be consumed in proper balance. I more fully developed this concept in my spring 2007 article on vitamin K2, “On the Trail of the Elusive X-Factor: A Sixty-Two-Year-Old Mystery Finally Solved.”
As a result of this research, in December of 2007 I published a hypothesis on the molecular mechanism of vitamin D toxicity in the journal Medical Hypotheses entitled “Vitamin D toxicity redefined: vitamin K and the molecular mechanism,” that emphasized interactions between vitamins A, D, and K. The following year, researchers from Tufts University published a paper in the Journal of Nutrition supporting this hypothesis, showing that vitamin A protects against vitamin D toxicity in part by helping to properly regulate the production of vitamin K-dependent proteins.
One question I have never been able to answer in any of these articles is the one everyone wants an answer to: what, precisely, is the proper ratio of vitamins A and D?
Dr. Linday and her colleagues offer a suggestion: poultry studies suggest optimal A-to-D ratios between four and eight. Similarly, in her own studies showing cod liver oil protects against upper respiratory tract infections, Linday supplied her patients with A-to-D ratios between five and eight.
They also point out that rat studies showing that vitamin A is toxic and antagonizes the effects of vitamin D used much higher ratios, ranging from 5,000 to 55,000!
It is refreshing to see a powerful defense of cod liver oil in the scientific literature, and especially refreshing to see the work of the Weston A. Price Foundation cited therein.
We owe a big thank you to Dr. Linda Linday (MD) of St. Luke’s-Roosevelt Hospital Center in NY, NY, Dr. John C. Umhau (MD, MPH) of the NIH in Bethesda, MD, Richard D. Shindledecker of New York Downtown Hospital in NY, NY, Dr. Jay N. Dolitsky (MD) of the New York Eye and Ear Infirmary in NY, NY and Michael F. Holick (PhD, MD) of Boston University Medical Center in Boston, MA.
Read more about the author, Chris Masterjohn, PhD, here.
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So what does this ratio imply about CLO/D3 dosages?
It’s great to see established vitamin D researchers making this argument
The liver/liver oil seems to be a very delicate issue. Since(among other things) the liver functions both as a storehouse of nutrients and also a detoxification organ, it could either be healthful or harmful depending on whether the animal (or fish) lived in a pristine environment or a polluted one. Given the widespread contamination of our oceans I have a lot of trouble believing that it is even possible to obtain a truly “pure” cod liver oil, despite the claims of purity by the sellers of said products.
Unless there was extensive lab testing and thorough documentation for a product showing not “low” but “zero” or “near-zero” levels of contamination I would not even consider ingesting it. Even then, the results of such a test would be questionable since there are a massive quantity of potentially health-damaging contaminants and it would be nigh on impossible and extremely cost prohibitive to even attempt to begin testing for all of them. And even if such a theoretical comprehensive safety test was conducted and came out “clean”, a result I would highly doubt possible, new contamination is occurring so rapidly in the world that the results would need to be repeated very frequently for them to matter at all.
Comments welcome.
This makes perfect sense if you realise that primitive man ate lots of organ tissues with ratios of A and D similar to that of CLO, but also got lots of sun exposure that increased their D levels to ratios probably similar to that which is described by these researchers.
Vitamins A and D participate in many many systems in the human body. It seems to me that the optimal level and/or ratio of these vitamins (and others) would depend on what outcome you are shooting for.
Just as you attack Cannell, I think you are vulnerable to the criticism of over-generalization, or optimistic extrapolation. “Poultry studies suggest” is weak, I’m sorry.
I would like to see thoughtful, non-combative discussion and research on various topics such as testosterone levels, autism, bone health, mental health, energy levels, cancer, immune response to viruses, gut health, etc etc. Both WAPF and Dr Cannell seem too invested in a particular letter, you are all getting defensive when you should be getting curious. You are not best serving the public good.
William, good point!
Isothiocyanate, the liver being a detoxification organ does not imply bioaccumulation of toxins in liver because the liver’s purpose is to make toxins excretable by conjugating them to water-soluble components; but it does imply that liver will be very high in nutrients needed for detoxification. You are right that many seafood produts are contaminated. This is addressed in many ways, most commonly molecular distillation, although there are alternatives. I would address this question to Dave Wetzel of Green Pastures as he has much more expertise in this area than I do.
Stephan, yes!
Dave, well this ratio is just a “suggestion” that I have not officially endorsed but what it means is that high-vitamin cod liver oil and some sunshine should do you well. Check the label of the product you are using to see the specific ratio, as ratios vary widely between different CLOs.
Chris
Dear Ed,
Thank you for writing. I agree that we should be approaching these issues with non-combatic, enthusiastic curiosity.
That’s why in the blog “More Attacks on Vitamin A,” I wrote the following:
“I would like to start out by saying that I respect Dr. Cannell’s efforts to raise awareness about the need for greater exposure to sunshine and vitamin D supplementation when adequate sunshine is unavailable, and that this post is not in any way a personal attack against Dr. Cannell or his work. Disagreement in science is the stone on which the knife of truth is sharpened, so in that sense Dr. Cannell and I are partners in cutting through the obscurity, uncertainty, and falsehood that lies in the way of achieving robust and radiant health.”
Personal attacks are never helpful, but sharp, to-the-point criticism often is.
If I had concluded that the ratio of vitamin A to D required by humans could be demonstrated by poultry studies, I agree it would be weak. I did not, however, make that argument. I was summarizing what the authors of the commentary wrote, which is why I stated that they had a “suggestion” to a question I had never been able to answer in my own articles. And when they cited this research, they cited in conjunction with their own experimental evidence showing cod liver oil with the vitamins at about the same ratio improved clinical endpoints. I don’t think their argument is weak, over-generalizing, or overenthusiastically extrapolating, and I don’t think I’m engaging in any of those merely for summarizing their statements.
Chris
Vitamins A and D participate in many many systems in the human body. It seems to me that the optimal level and/or ratio of these vitamins (and others) would depend on what outcome you are shooting for.
Just as you attack Cannell, I think you are vulnerable to the criticism of over-generalization, or optimistic extrapolation. “Poultry studies suggest” is weak, I’m sorry.
I would like to see thoughtful, non-combative discussion and research on various topics such as testosterone levels, autism, bone health, mental health, energy levels, cancer, immune response to viruses, gut health, etc etc. Both WAPF and Dr Cannell seem too invested in a particular letter, you are all getting defensive when you should be getting curious. You are not best serving the public good.
It’s an uncertain area. I know you’re aware of the Scandanavian studies that find higher vit D associated with more mortality. Do you find convincing Cannell’s speculation that this is confounding from cod liver oil? In the only study from Scandavia that measured retinol intake (the recent colon cancer study that you’ve blogged about), this speculation got a strong boost.
Cannell also bases his theory on mecahnistic speculation regarding the interraction between the VDR, RXR, and RARs. Since I learned half of what I know about these receptors from you, I know you understand his argument that RA may sequester the RXR away from calcitriol.
I suppose the finding that in the pancreas, RA increases the number of VDRs is a potential answer to Cannell. Wonder if that result is generalizable?
Can anybody give any advise how (ratio) vitamins A and K should be taken along the vitamin D3. Is there any literature references? I live in Finland which has little or no sun shine during the winter months.