New research has once again placed optimum vitamin D intake at much higher than the current recommended amount.

The study of 138 subjects suggested a daily dose of 3800 IU for those with adequate blood vitamin D levels, and 5000 IU each day for those who are vitamin D deficient.

The current recommended intakes for vitamin D are as low as 200 IU daily for those aged 19-50, and go only as high as 600 IU daily for those over the age of 70.

 Dr. Mercola's Comments: 
More and more scientific evidence is emerging, confirming that currently recommended intakes of vitamin D are completely insufficient and FAR below your optimal levels. 

I'm pleased to see that this study upped the recommended dosages in order to achieve a healthier vitamin D level. But even their increased target serum concentration of 75 nmol/L is below the optimal level for maximum health benefits.

What is the OPTIMAL Level of Vitamin D?

The “normal” 25-hydroxyvitamin D lab values are 50-140 nmol/L (20-56 ng/ml).

However, this range is too broad to be ideal. 

In fact, your vitamin D level should never be below 82 nmol/L (32 ng/ml), and any levels below 50 nmol/L (20 ng/ml) are considered serious deficiency states, increasing your risk of as many as 16 different cancers and autoimmune diseases like multiple sclerosis and rheumatoid arthritis. 

The OPTIMAL value that you're looking for is 115-128 nmol/L (50-55 ng/ml), which is still slightly higher than what this study aimed for.

Keeping your level in this range, and even erring toward the higher numbers in this range, is going to give you the most protective benefit.

A study published in March 2007 supports this higher range. (For a PDF copy of the full study, see this link.)

After assessing data from two studies, they found that individuals with serum 25(OH)D of approximately 132 nmol/L (52 ng/ml) had a 50 percent lower risk of breast cancer than those with serums of less than 33 nmol/L (13 ng/ml). 

The researchers pointed out that the 132 nmol/L is high enough to provide the needed benefit, but has been found by other scientists to be low enough to avoid health risks.

This blood level corresponds to a supplemental vitamin D intake of 4,000 IU (International Units, a measure of vitamin activity) per day, which far exceeds even the National Academy of Sciences' upper limit of 2,000 IU/day, and blows the current recommendation of 200 IU/day out of the water.

However, even though having some general guidelines on how much vitamin D you should take, your individual needs may be higher or lower than the recommended dosages. So how do you know how much YOU need to take to get within these optimal levels?

Check Your Vitamin D Levels Using the Correct Test

I recommend you check your vitamin D levels regularly to make sure you stay within the optimal range, especially during the winter months when lack of sunshine can exacerbate vitamin D deficiency.

Please bear in mind when you go for the test that there are TWO vitamin D tests: 1,25(OH)D and 25(OH)D.

The correct test your doctor needs to order is 25(OH)D, also called 25-hydroxyvitamin D, which is the better marker of overall D status. This is the marker that is most strongly associated with overall health.

When you receive your results, please also note the difference between normal and optimal. You don't want to be average here; you want to be optimally healthy. There is a high likelihood that the reference ranges of your lab will not be correct. So please be sure and use the values I listed earlier to guide your treatment.

Are Oral Vitamin D Supplements Your Best Choice?

Many experts would disagree with me about this, but after reviewing the evidence and having personally overdosed on vitamin D, I am convinced that although you can clearly get some benefit from oral vitamin D, it is NOT your best choice -- it is simply too easy to overdose.

The major danger of overdosing on vitamin D is that there are no symptoms, just like most with high blood pressure; you frequently don't have symptoms until it is too late.  Once you overdose on vitamin D, there is no simple way to treat it other than time, and complete avoidance of vitamin D.  Another danger of overdosing on vitamin D is that it will cause nearly similar complications as underdosing. 

An overdose of oral vitamin D can cause a number of serious problems, including:

• Vomiting
• Constipation
• Weight loss
• Kidney failure
• Calcification of the arteries

Even with this approach, it may take many months to normalize your levels from elevated levels due to taking ORAL vitamin D. 

However, this simply does not happen when you use the sun as a source of vitamin D, because your body has a built-in “feedback loop” that automatically prevents overproduction of vitamin D.

Therefore, rather than supplements, I believe it's important to strive to obtain your vitamin D naturally, from safe sunshine exposure. 

There are, however, certainly times when it can be nearly impossible to get enough sun. 

The darker your skin is, the farther away from the equator you are, and the further away you are from the summer months, the less likely it is that you will produce adequate vitamin D levels from sun exposure alone.

In these cases, supplementing with vitamin D is acceptable, but you need to be VERY cautious when using oral vitamin D preparations. I would not recommend using them at all UNLESS you monitor your blood levels of vitamin D regularly. 

If You Take Oral Vitamin D, Make Sure You Take the Right Kind

There is one other thing you need to be aware of if you choose to use an oral vitamin D supplement and that is that there are basically two types. The natural one is D3 (cholecalciferol), which is the same vitamin D your body makes when exposed to sunshine. 

The synthetic one is vitamin D2, which is sometimes called ergocalciferol.

Once either form of the vitamin is in your body, it needs to be converted to a more active form. Vitamin D3 is converted 500 percent faster than vitamin D2.

Interestingly, it was previously thought that the kidney exclusively performed this function; at least that is what I was taught in medical school. 

However, in 1998 Dr. Michael Holick, the person who discovered activated vitamin D, showed that many other cells in your body can make this conversion, but they use it themselves, and it is only the kidney that makes enough to distribute to the rest of your body.

This is new information that most physicians are simply unaware of, as it was discovered after they went to medical school.

Unfortunately, nearly all the prescription-based supplements contain synthetic vitamin D2, which was first produced in the 1920s through ultraviolet exposure of foods. The process was patented and licensed to drug companies for use in prescription vitamins. So if you receive a prescription for vitamin D from your doctor, be aware that it is almost assuredly vitamin D2. 

I strongly believe getting enough vitamin D is  vital to your health, and that the best way for you to optimize your vitamin D levels is through proper sun exposure. I wrote not only a Special Report on the topic, but dedicated an entire book to the subject. The book is called Dark Deception and we hope to have it out this summer.

I've also written many articles on how to tan safely and optimize your vitamin D levels naturally through appropriate sunshine exposure. If you missed them, please take a moment to review the articles listed under Related Articles.
 
Sources:
American Journal of Clinical Nutrition June 2008; 87(6):1952-1958 (Free Full-Text Report)

RESOURCE/SOURCE: http://articles.mercola.com/sites/articles/archive/2008/06/28/if-you-choose-to-take-oral-vitamin-d-how-much-should-you-take.aspx?source=nl on Saturday June 28, 2008.