By Dr. Mercola
Research into vitamin D over the past two decades has revealed a spectacular amount of solid evidence backing its importance for countless aspects of human health.
In the past, vitamin D was primarily regarded as an important nutrient for bone health, and it was conventionally thought that a person had enough vitamin D as long as they didn't have bone diseases like rickets or osteomalacia.
But new research shows how wrong this assumption was, as higher levels of vitamin D are necessary to provide protection from more serious chronic diseases such as cancer, heart disease, infections, multiple sclerosis and more.
The factor that sets vitamin D apart from many other nutrients is that vitamin D receptors are present in virtually every tissue and cell in your body, and as a review in the Journal of Evidence-Based Complementary & Alternative Medicine reported:
" … adequate vitamin D status is essential for optimal functioning of these tissues and cells.
An impressive body of research has accumulated over the past two decades providing new information about the role of vitamin D in prevention of a broad range of diseases."
Have You Had a 25(OH)D Test?
If you have never had your vitamin D levels tested, I urge you to consider doing so very soon, as simply assuming your levels are in the healthy range is quite risky.
Vitamin D deficiency is at epidemic proportions in the United States and many other regions around the world today, largely because people do not spend enough time in the sun to facilitate this important process of vitamin D production..
So the first step to ensuring you are receiving all the benefits of vitamin D is to find out what your levels are using a 25(OH)D test, also called 25-hydroxyvitamin D.
There are two vitamin D tests -- 1,25(OH)D and 25(OH)D -- but 25(OH)D is the better marker of overall D status. It is this marker that is most strongly associated with overall health, and it is the one you should ask your physician for.
Alternatively, you can have your vitamin D levels tested right in your own home by joining the GrassrootsHealth D* Action Study. D*Action is a worldwide public health campaign which aims to solve the vitamin D deficiency epidemic through focusing on testing, education, and grassroots word of mouth.
When you join D*action, you agree to test your vitamin D levels twice a year during a five-year program, and share your health status to demonstrate the public health impact of this nutrient. There is a $60 fee each 6 months ($120/year) for your sponsorship of the project, which includes a complete new test kit to be used at home, and electronic reports on your ongoing progress.
You will get a follow up email every six months reminding you "it's time for your next test and health survey." To join now, please follow this link to the sign up form.
What Do Your Vitamin D Test Results Mean?
The point of vitamin D testing is, of course, to be sure you are maintaining a therapeutic level of vitamin D in your blood. A few years back, the recommended level was between 40 to 60 nanograms per milliliter (ng/ml), but more recently the optimal vitamin D level has been raised to 50-70 ng/ml, and when treating cancer or heart disease, as high as 70-100 ng/ml.
According to the chart below, optimizing your vitamin D levels can help you to prevent at least 16 different types of cancer, along with heart disease, diabetes, Alzheimer's, the flu and much, much more.
Why You Should Strive to Get Your Vitamin D Fromthe Sun
It's been suggested that only about 30 percent of Americans' circulating vitamin D is the product of sunlight exposure. This is an unfortunate byproduct of public health agencies' misguided advice to stay out of the sun to avoid cancer (when in fact vitamin D from sun exposure will prevent cancer).
The truth is, vitamin D from sun exposure is the BEST way to optimize your vitamin D levels, and a recent interview with Dr. Stephanie Seneff brought the importance of getting your vitamin D from sun exposure to a whole new level.
I've consistently recommended getting your vitamin D from regular sun exposure whenever possible, but Dr. Seneff's review of how vitamin D—specifically from sun exposure—is intricately tied to healthy cholesterol and sulfur levels, makes this recommendation all the more important.
As a quick summary, when you expose your skin to sunshine, your skin synthesizes vitamin D3 sulfate. Unlike oral vitamin D3 supplements (which are unsulfated), sunlight-formed vitamin D sulfate is water soluble. The water-soluble form can travel freely in your bloodstream, whereas the unsulfated form needs LDL (the so-called "bad" cholesterol) as a vehicle of transport. Dr. Seneff's suspicion is that the oral non-sulfated form of vitamin D may not provide all of the same benefits as the vitamin D created in your skin from sun exposure, because it is not readily converted into vitamin D sulfate.
I believe this is a very compelling reason to make a deliberate effort to get most of your vitamin D requirements from exposure to sunshine, or by using a safe tanning bed (one with electronic ballasts rather than magnetic ballasts, to avoid unnecessary exposure to EMF fields). Safe tanning beds also have far less of the dangerous UVA than sunlight; while unsafe ones have more UVA than sunlight. If neither of these are feasible options, then you should take an oral vitamin D3 supplement.
It is very difficult to get enough vitamin D from food sources alone, as very few foods naturally contain vitamin D -- and those that do will not contain enough to optimize your levels.
Interestingly, the only vitamin not found in breast milk is vitamin D. This can be considered a giant clue that we were NOT designed to get our vitamin D through the oral route through our food. Rather, we were designed to produce it by exposing our skin to natural sunlight. Lack of sun exposure is really the very root of the problem, as historically speaking, vitamin D deficiency is a fairly recent health concern.
How Much Sun Exposure Do You Need?
Occasional sunlight exposure to your face and hands is not sufficient for vitamin D nutrition for most people. To optimize your levels, you need to expose large portions of your skin to the sun, and you may need to do it for more than a few minutes.
Contrary to popular belief, the best time to be in the sun for vitamin D production is actually as near to solar noon as possible. Ultraviolet light from the sun comes in two main wavelengths -- UVA and UVB. It's important for you to understand the difference between them, and your risk factors from each.
First there is UVB, the healthy wavelengths that help your skin produce vitamin D. Then there is UVA, which is generally considered the unhealthy wavelengths because they penetrate your skin more deeply and cause more free radical damage. Not only that, but UVA rays are quite constant during ALL hours of daylight, throughout the entire year -- unlike UVB, which are low in morning and evening, and high at midday.
So to use the sun to maximize your vitamin D production and minimize your risk of skin damage, the middle of the day (roughly between 10:00 a.m. and 2:00 p.m.) is the best and safest time. During this UVB-intense period you will need the shortest sun exposure time to produce the most vitamin D.
As far as the optimal length of exposure, you only need enough to have your skin turn the lightest shade of pink. This may only be a few minutes for those who have very pale skin.
Once you have reached this point your body will not make any additional vitamin D and any further exposure will only result in damage to your skin. Most people with fair skin will max out their vitamin D production in just 10-20 minutes, or, again, when their skin starts turning the lightest shade of pink. Some will need less, others more. The darker your skin, the longer exposure you will need to optimize your vitamin D production.
If You Take A Vitamin D Supplement …
If sun exposure or a safe tanning bed are not realistic options, you can use an oral form of vitamin D. Make sure, if you supplement, that you are using vitamin D3 (cholecalciferol) and not the inferior form known as vitamin D2 (ergocalciferol). The latest research actually shows D3 is approximately 87% more potent in raising and maintaining vitamin D concentrations and produces 2- to 3-fold greater storage than does D2.
Furthermore, if you are following the U.S. Recommended Dietary Allowance for vitamin D -- a measly 600 IU (international units) a day -- there is a good chance you will be missing out on the important benefits vitamin D has to offer.
Based on recent research published by Grassroots Health from the D*Action study, the average adult needs to take 8,000 IU's of vitamin D per day in order to elevate his or her levels above 40 ng/ml -- the bare minimum requirement necessary for disease prevention. Ideally, you'll want your levels to be between 50-70 ng/ml.
As Carole Baggerly, director and founder of GrassrootsHealth, noted:
"We just published our very first paper. We have about 10 people in this study now that are taking 50,000 IU a day and they're not reaching a potential toxicity level of 200 ng/ml. It should be noted, however, that this is not a recommended intake level. The study reported data on about over 3,500 people.
… One very significant thing shown by this research was that even with taking the supplement, the curve for the increase in the vitamin D level is not linear. It is curvilinear and it flattens, which is why it's even hard to get toxic with a supplement."
This means that even if you do not regularly monitor your vitamin D levels, your risk of overdosing is going to be fairly slim -- even if you take as much as 8,000 IU's a day. As an aside, there is evidence that the safety of vitamin D is dependent on vitamin K, and that vitamin D toxicity (although very rare with the D3 form) is actually aggravated by vitamin K2 deficiency. So if you take oral vitamin D, ideally you should take vitamin K2 as well or use organic fermented foods that are high in vitamin K2, as you need about 150 mcg per day.
Remember, unless you get a deep dark tan, which is a pretty good gauge that your vitamin D levels are where they need to be, it is wise to get your blood levels checked; that is the only way to know for certain you have reached therapeutic levels.
My hope is that you will use this information to your advantage, as I believe optimizing your vitamin D levels is one of the simplest and most profound steps you can take to improve and maintain your health. For more information, and to follow the latest updates surrounding this "sunshine" nutrient, visit VitaminD.Mercola.com.