Vitamin D are almost entirely negated with vitamin A (retinol) intake

[Guest guest]

Read This Shocking Vitamin D Report or You'll Kick Yourself for the

Next Decade

Posted by Dr.

Mercola | March 16 2010

| 178,593 views

 

 

Email

this to a friend

Share this article

 

 

Next Article

 

 

The

British Medical Journal has published a remarkable paper

confirming that low vitamin D levels obtained in the past are a risk

factor for developing colon cancer in the future.

 

But the study contained an even more significant finding -- as Dr.

Cannell's site has reported

before, vitamin A, even in relatively low amounts, can thwart

vitamin D's association with reduced rates of colon cancer.

 

This is the largest study to date showing vitamin A blocks vitamin D's

effect.

 

Hidden on page eight of the paper was one sentence and a small table,

showing that the benefits of vitamin D are almost entirely negated in

those with the highest vitamin A (retinol) intake.

 

And the retinol intake did not have to be that high -- only about 3,000

IU/day. Young autistic children often take 3,500 IU of retinol a day in

their powdered multivitamins, which doesn't count any additional

vitamin A given in high single doses.

 

The finding explains some of the anomalies in other papers on vitamin D

and cancer -- similar studies sometimes have widely different results.

This may be because the effect of vitamin A was not taken into account.

In some countries, cod liver oil, which contains vitamin A, is commonly

used as a vitamin D supplement, and in others it is used more rarely,

causing differences in the results.

Sources:

  The

Natural Advocate February 28, 2010

 

  Vitamin D Council

 

  British

Medical Journal, BMJ 2010;340:b5500

 

 

 

 

 

 

 

Dr.

Mercola's Comments:

 

 

 

 

 

 

 

 

 

 

If you already to the excellent newsletter from The Vitamin D Council then

you’re aware of this important information. If not, I highly recommend

becoming a r, as The Vitamin D Council is a great source of

information on this vital topic.

In this recent article by Dr. Cannell, he discusses the latest

research published in the British Medical Journal, which

confirms his previous assertion: that too

much vitamin A negates many of the beneficial health effects of vitamin

D.

In his December

2008 issue, Dr. Cannell explained:

 

“The crux of the problem is that a form of vitamin A, retinoic

acid, weakly activates the vitamin D response

element on the gene and perhaps blocks vitamin D's more robust

activation. In fact, the authors of a 1993

study state "there is a profound inhibition of vitamin

D-activated...gene expression by retinoic acid."

 

So what does this mean?

 

Vitamin A versus Vitamin D

 

Well, naturally, since appropriate vitamin D levels are crucial

for your health, it means that it’s essential to have the proper

ratio of vitamin D to vitamin A in your body.

This also means that vitamin A supplementation is potentially

hazardous to your overall health, as vitamin D plays a significant role

in a large number of common diseases and afflictions.

In a paper

published in the August 2007 issue of the American Journal of

Clinical Nutrition, Anthony Norman, an international expert on

vitamin D, identified vitamin D's potential for contributions to good

health in:

 

Your adaptive and innate immune systems

The secretion and regulation of insulin by your pancreas

Heart and blood pressure regulation

Muscle strength

Brain activity

 

There are only 30,000 genes in your body and vitamin D has been

shown to influence over 2,000 of them. That’s one of the primary

reasons it influences so many diseases, including:

 

 

 

 

Cancer

Hypertension

Heart disease

 

 

Autism

Obesity

Rheumatoid arthritis

 

 

Diabetes 1 and 2

Multiple Sclerosis

Crohn"s disease

 

 

Flu

Colds

Tuberculosis

 

 

Septicemia

Aging

Psoriasis

 

 

Eczema

Insomnia

Hearing loss

 

 

Muscle pain

Cavities

Periodontal disease

 

 

Athletic performance

Macular degeneration

Myopia

 

 

Pre-eclampsia

Seizures

Fertility

 

 

Asthma

Cystic fibrosis

Migraines

 

 

Depression

Alzheimer’s disease

Schizophrenia

 

 

 

 

Vitamin A production is tightly controlled in your body. The

substrate, or source of the vitamin A, are carotenoids from vegetables

in your intestine. Your body converts these carotenoid substrates to

exactly the right amount of retinol. However, when you take vitamin A

as retinol directly, such as in cod liver oil, you bypass all the

natural controls in this closed system.

Ideally, you’ll want to provide all the vitamin A and vitamin D

substrate your body needs in such a way that your body can regulate

both systems naturally.

This is best done by eating colorful vegetables (for vitamin A)

and by exposing your skin to sun every day (for vitamin D).

 

Even Low Amounts of Vitamin A Can Negate Benefits

of Vitamin D

 

Given that cancer, heart disease and diabetes are

three of the top causes of death in the United States, ensuring that

you are getting enough of this crucial vitamin should be a top priority.

 

A study by Dr. William Grant, Ph.D., another internationally recognized

research scientist and vitamin D expert, found that about 30

percent of cancer deaths -- which amounts to 2 million worldwide

and 200,000 in the United States -- could be prevented each year with

higher levels of vitamin D.

Knowing this, it’s clearly important to avoid anything that might

hamper your vitamin D production, and it appears vitamin A

supplementation may indeed have this effect.

I highly recommend you read

Dr. Cannell’s article about this latest BMJ study, in its entirety,

as he explains quite well how even the researchers themselves seem to

have missed this crucial connection.

He writes:

 

“Dr. Mazda Jenab and his 45 colleagues from the

International Agency for Research on Cancer confirmed that low vitamin

D levels are a risk for colon cancer in a dose response manner; those

with the highest levels were about twice as less likely to develop

colon cancer compared to those with the highest levels.

 

However, hidden on page eight is one sentence and a small table, which

shows that the benefits of vitamin D are almost entirely negated in

those with the highest vitamin A intake. And the retinol intake did not

have to be that high in these older adults to begin to negate vitamin

D's effects, about 3,000 IU/day.

Remember, young autistic children often take 3,500 IU of

retinol a day in their powdered multivitamins, which doesn't count any

additional vitamin A given in high single doses.

 

This is the largest study to date showing vitamin A blocks vitamin D's

effect and explains some of the anomalies in other papers on vitamin D

and cancer.”

 

 

 

 

The Synergistic Effects of Vitamin A on Vitamin D

 

It’s highly unfortunate, but many 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 spent many hours reviewing this issue in the latter part of

2008, and as a result, I 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.

I had recommended cod liver oil as a source of vitamin D for quite

some time, prior to this revision. My stance 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, as I began reviewing the latest research, I realized

there was compelling evidence that the ratios of these two

vitamins may be of paramount importance in order to extract optimal

health benefits. And this latest study appears to confirm that theory.

It’s important to understand that vitamin A is essential for your

immune system and a precursor to active hormones that regulate the

expression of your genes just like vitamin D, and the two 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, we 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.

You also need to discern between various forms of vitamin A.

It is 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.

 

How Can You Ensure Proper Ratios of Vitamins A

and D?

 

As Dr. Cannell has stated in earlier writings on this topic, the

ideal way to obtain the proper vitamin A to D ratio is to obtain it the

way your body was designed to obtain it:

 

Vitamin A through your diet, in the form of colorful vegetables

 

Vitamin D through daily sun exposure on your skin

 

For more information about the vital importance of these two

vitamins, please review the articles below.