Dr. Mercola January 03 2009 93,916 views
A landmark paper from the Vitamin D Council asserts that a form of vitamin A, retinoic acid, can block the activity of vitamin D by weakly activating the vitamin D response element on genes. Since vitamin D levels are crucial for human health, that means it is essential to have the proper ratio of vitamin D to vitamin A in your body.
This means that vitamin A supplementation is potentially dangerous. Vitamin A production is tightly controlled in your body, the source (substrate) being carotenoids from vegetables in your intestine. Your body uses these carotenoid substrates to make exactly the right amount of retinol. But when you take vitamin A as retinol directly, such as in cod liver oil, you intervene in this closed system and bypass the controls.
The goal is to provide all the vitamin A and vitamin D substrate your body would have obtained in a natural state, so your body can regulate both systems naturally. This is best done by eating colorful vegetables and by exposing your skin to sun every day.
As scientific findings about vitamin D’s health benefits race forward at breakneck speed, another issue has surfaced – the synergistic effects of vitamin A on vitamin D. More specifically, how people in developed countries are potentially sabotaging the multitude of health benefits they could receive from adequate vitamin D, by taking excessive amounts of vitamin A, either in the form of multi-vitamins or cod liver oil.
I have spent many hours carefully analyzing this issue over the past three months, and as a result, I’ve already issued a revision of my long held recommendation for cod liver oil. If you missed that important update, please take the time to review it now.
My previous recommendation was based on the fact that cod liver oil contains vitamins D and A in addition to healthy omega-3 fats. These vitamins are essential for most everyone who cannot get regular sun exposure year-round.
However, more recent research offers compelling evidence that the ratios of these two vitamins may be of paramount importance in order to extract optimal health benefits.
Vitamin A, which is essential for your immune system just like vitamin D, is also a precursor to active hormones that regulate the expression of your genes, and they work in tandem. For example, there is evidence that without vitamin D, vitamin A can be ineffective or even toxic. But if you’re deficient in vitamin A, vitamin D cannot function properly either. So proper balance of these two vitamins is essential. Too much or too little of either may create negative consequences.
Unfortunately, modern cod liver oil does not supply these vitamins in healthy ratios to each other.
Think of it as the issue of omega-3 vs omega-6.
Their ratio should be close to 1:1, but our modern diet, high in processed foods, has thrown this balance so far out of whack that omega-3 supplementation is essential for nearly everyone, while at the same time reducing your intake of omega-6 is highly recommended.
The issue of vitamin A and vitamin D is very similar.
Unfortunately, we simply do not yet know the optimal ratios between these two vitamins, but it is clear that nearly all cod liver oil products supply them in levels that do not appear to be ideal.Manufacturers are free to add or subtract as much vitamin A or D as they see fit.
It’s All About Balance
One of the most important pieces of new information that influenced my thinking on this issue was two recent meta-analyses. The first one showed that people who took vitamin A in the form of cod liver oil or other supplements, had a 16 percent increase in dying .
The other study showed that unlike third world countries where vitamin A supplementation appears to decrease infections, vitamin A supplementation in developed countries like the U.S. actually increased infections.
How could that be?
This is where the appropriate ratios come in.
The researchers believe these results are due to massive vitamin A deficiencies in the third world, because most of their calories are from grains, and they simply don’t have an opportunity to consume as many fresh fruits, vegetables, butter, eggs and other vitamin A-containing foods that those in the developed world do.
Conversely, current research have not been able to find any vitamin A deficiency at all in developed countries like the U.S, but approximately 5 percent have vitamin A toxicity.
Moving on to vitamin D.
There’s mounting evidence that vitamin D protects against a number of cancers, including colon cancer. But paradoxically, researchers found that many of those with higher vitamin D levels do not seem to have this benefit. Again – it’s likely to be all about the ratios.
A bright Harvard researcher carefully analyzed the data and found that when he removed the people with high vitamin A and high vitamin D levels, those with normal vitamin A levels and high vitamin D levels continued to have reduced risk of colon cancer.
Hence, those who did not supplement with vitamin A gained the protective effect from higher levels of vitamin D!
How Excessive Vitamin A Can Interfere with Vitamin D’s Benefits
Dr. Cannell and other prominent researchers believe that supplementing with vitamin A can reduce the effectiveness of vitamin D by inhibiting the binding of its active form to your DNA, effectively preventing its ability to regulate the expression of your vitamin D-responsive genes.
But before we go further, let’s clarify one thing: It’s the retinoic acid (retinol) form of vitamin A that is problematic. Not beta carotene.
Beta carotene is not a concern because it is PRE-vitamin A. Your body will simply not over-convert beta carotene to excessive levels of vitamin A. So taking beta carotene supplements is not going to interfere with your vitamin D.
Additionally, if you are deficient in vitamin D and supplement with vitamin A (retinoic acid), you’re more likely to suffer vitamin A toxicity.
In fact, vitamin A toxicity may be more common than you think.
Why?
Because vitamin A toxicity can lead to liver disease, but very few physicians will ever think to inquire about vitamin A supplements or cod liver oil when presented with a liver disease case.
One previous study published in the journal Gastroenterology concluded:
“It was concluded that at least in some western countries chronic vitamin A consumption might represent an appreciable cause of chronic liver disease, the recognition of which mainly relies on expert liver biopsy interpretation. The data also indicate that prolonged and continuous consumption of doses in the low "therapeutic" range can result in life-threatening liver damage.”
If you search PubMed you’ll find nearly 85 reports on vitamin A-induced liver disease alone.
So clearly, the key to optimal health is having the proper ratio of vitamin D to vitamin A in your body.
How Can You Ensure Proper Ratios of Vitamins A and D?
As Dr. Cannell states, the best way to obtain the proper vitamin A to D ratio is to obtain it the way you were designed to obtain it:
For more information about the vital importance of these two vitamins, please review the articles below.
bmc, going out on a sunny day in this northern climate where I reside could mean one's extremities plus dropping-off and the only fresh greens are lichens. It is the red meats with lashings of saturated fats that keep me fit and well.
I have been giving codliver oil to my kids since birth I mentioned earlier and I take it myself when I feel like and think to (I hate the taste), but haven't since the new info came out. I take other supplements as well and I now I looking at the A and D content in them. One of my newer vitamins that was recommended is called "More than a Multiple" it has 10,000 IU of Vit A and 400IU of Vit E. to make sure I get enough calicium I also take Mega Minerals (1/2 the dose) which has 100IU of Vit D and no Vit A. I am just wondering if one takes various vitamins and minerals, how can we be sure to be getting this EXACT ratio? I feel like I would be doing myself more harm than good if I stopped taking these. I have 3 small children and rarely get any breaks due to my husband never being home. I have a hard enough time giving them all that they need, taking care of myself as well is not always easy. Sure it is ideal getting everything from our fruits and Veggies etc.. but I have not been able to do that for numerous reasons. I really am not sure of what I should and shouldn't be taking anymore! :-(
OOPS!! That last post should have read "400IU of Vitamin D NOT E!
I would like to encourage others who have suffered with exzema for any length of time like I did to consider the Vitamin D /omega 3 connection. I used to work as a lifeguard on the beach and swam every summer as a kid outside and didn't suffer from any skin porblems. I had enough Vit D from sun exposure. I got married, had a child and wasn't in the sun as much and ended up with exzema on my hands for 28 years. I tried everything, it would get better but never cleared up completely until resently when I started reading about the Vit. D and omega 3 connection to poor health and I thought I'd give higher doses a try. Well, to my joy and amazement, after suffering with red, swollen scaling, itchy hands for 28 years, 6 capsules of omega 3 fish oil and 4000 I.U. of Vitamin D a day has cleared up and healed the skin on my hands. No more itching, and the skin is really healing. This is really the only thing I have done significantly differently. I've been practicing holisticly for this whole time, juicing, fasting, supplementing, rotation dieting, elimination dieting, everything, this is truely a miracle for me. I really believe I have been severely Vit. D deficient. It's the only explanation. Thank you for the info on the cod liver oil. I think caution is a worthy consideration. Everyone is different but knowledge is our key to a long and fruitful life. Use it wisely and use it to help others to their full potential. Maybe someone else can avoid suffering because of what we are all learning and sharing with one another! Blessings to you all, Liz D.
hi Angelwings; i was happy to hear of your great success with the eczema skin condition. I have a nasty patch of what i think is psoriasis on my hand which developed for the first time last winter.
A few days ago i saw my doctor to ask her for a proper vit D test and told her i was trying Vit D3 drops on my hand. She looked surprised and told me that one of the most popular medications out there for psoriasis is Dovonex, which is basically a synthetic Vit D2 cream. (please forgive me if i spelled the medication name incorrectly). So if this cream is truly a help to psoriasis sufferers, it seems more cost effective to simply raise your vit D3 levels to optimum levels, and as you said, use the proper amount of omega 3 oils for psoriasis or eczema or any skin condition. It is well worth a try, and not very expensive to do. Since dermatologists often recommend UV light for these conditions, it makes a tremendous amount of sense. Why the connection between UV light exposure and vit D was not made before baffles me :)
How many milligrams are in your fish oil supplements? I am trying to decide how much fish oil to take per day. Even one capsule gives me a tremendous lift in energy!
We live in the Pacific Northwest (coastal region of BC, Canada) and we have prolonged light deficient days, and our region suffers from one of the highest rates of winter depression in the world due to high rainfall/cloudy skies.
I would like to add that I believe that optimizing blood levels of Vit D3 will, in the future, be the first course of action physicians will take in the treatment of depression. This is such an exciting time we are living in.
For those of you suffering from depression, talk with your doctor about using D3 instead of antidepressants. I have direct experience with this, and it works wonderfully.
Hey anglewings Could you tell me the brands of fish capsules and vit D you used? Also about how much do you weigh (sorry)
There always seems to be something missing in every discussion I’ve seen concerning taking cod liver oil. No one ever mentions the importance of controlled moderation, dosage, the best way to take it, or how to determine how much and how often it should be taken.
As a lifetime collector of natural home remedies, I feel compelled to offer some information you should find useful and interesting. The following is a synopsis of an old country doctor’s advice from over 50 years ago:
When cod liver oil is taken randomly the benefits and effects it can have on your body are unpredictable. If you have food or drink in you stomach when you take it, there is no way of knowing how much is absorbed and used by your body or how much passes through.
Since it is easy to overdose on cod liver oil, and many people do, wouldn’t it be nice to know precisely how much to take and the best way to take it? The following is a formula you should consider. I have enjoyed the benefits of taking this formula for over 30 years.
Put one teaspoon (no more no less) of cod liver oil in a whisky shot glass. Fill the glass to the brim with “whole milk” (not the white water that claims to be milk, it won’t work) then mix thoroughly with a knife. For palatability reasons you can choose a brand of oil that does not have the fish taste.
Take this formula every day first thing in the morning before you eat or drink anything. After one week your skin will have a more youthful look, and any dry skin problems should be gone. This formula is the ideal dose for most people, however if you notice a trace of transparency in your skin after taking it for a week, try taking it every other day, but maintain the same dosage.
Using whole milk stimulates rapid digestion that allows the formula to be quickly digested and metabolized in the stomach so its benefits can be absorbed by the body, and it doesn’t have a chance to mix with food or drink and get wasted in the lower intestines.
Wonderful!
Reading Jonathan S Christie's book 'Food for Vitality' 25 odd years ago woke me up to the omega EFA imbalance and deficiency connection to atopia and inflammation, but the good doctor had no data about D3.
Trying to persuade people to drop their intakes of refined polyunsaturated and trans oils and margarines has resulted in myself being branded as a crank many times.
So it is even more wonderful reading this 'proof of the pudding' posting.
Doubly wonderful that your cure related so wonderfully to the things you truley enjoy.
The post that stated severe liver toxicity from the consumption of polar bear liver made a common error: The toxicity was NOT due to the vitamin A, but due to the presence of toxic alkaloids! During the winter months, polar beers eat lichen, not fish (or at least not much fish!), and this lichen has extremely toxic chemicals in it. Fortunately, these alkaloids are harmless to the polar beers, but toxic to those that EAT the polar bear livers.
This is why the smart Eskimos (and others), do NOT eat polar beer livers in the winter, but can freely eat them during the warmer months. It's a long-standing story, but a myth, just the same. (Thank the Dean of the Nutrition Department at Cornell from 1976--Dr. Paul Buck, for this fact!)
Interesting stuff!
Thank you
Clearly some people don't want to hear it, but it needed to be said. I wanted to say much the same thing, but couldn't figure out how to do it without being blunt. For those who can read between the lines you said something very important here regarding marketing. Thanks for an honest and thought-provoking post.
To support his contention that cod liver oil contributes to hip fractures, Dr. Cannell supplied a single reference. This reference was a compilation of estimated fracture rates in different European countries. Norway, which is the Scandinavian country where cod liver oil is widely used, was not included. The incidence of hip fracture was strongly associated with life expectancy; the authors suggested that this was in part because the countries with the best medical care were the most likely to readmit patients for a fracture after they had already been discharged once, and therefore count the same fracture twice. Sweden, where 47 percent of fractures were counted more than once, had the highest fracture rate of any country. No information about the intakes of vitamin A, vitamin D, or cod liver oil was reported in the study.