Before considering supplementation with vitamin D, it would be wise to have your vitamin D level tested. This is best done from a nutritionally oriented physician. It is very important that they order the correct test. The advantage of having your medical doctor perform the test is that it will usually be covered by your medical insurance.

Don't Be Fooled -- Order the Correct Test

There are two vitamin D tests -- 1,25(OH)D and 25(OH)D.

25(OH)D is the better marker of overall D status. It is this marker that is most strongly associated with overall health.

The correct test is 25(OH)D, also called 25-hydroxyvitamin D

Please note the difference between normal and optimal. You don't want to be average here; you want to be optimally healthy.

Primitive man likely developed in tropical and sub-tropical conditions with large exposure to UV-B and its secondary consequence to skin exposure, vitamin D.

Primitive environmental availability of a nutrient does not necessarily establish the higher requirements, but these exposures would have influenced the evolution of the relevant physiology, and such concentrations should at least be considered presumptively acceptable.

Some experts may disagree with the following healthy ranges, but they are taken from healthy people in tropical or subtropical parts of the world, where they are receiving healthy sun exposures. It seems more than reasonable to assume that these values are in fact reflective of an optimal human requirement.

 (Holick MF. Calcium and Vitamin D. Diagnostics and Therapeutics. Clin Lab Med. 2000 Sep;20(3):569-90)

If you have the above test performed, please recognize that many commercial labs are using the older, dated reference ranges. The above values are the most recent ones based on large-scale clinical research findings.

Make Sure Your Lab Uses the Correct Assay

There are a number of different companies that have FDA approval to perform vitamin D testing, but the gold standard is DiaSorin. Their radioimmunoassay (RIA) method for measuring total vitamin D levels has become the gold standard, not because it’s more accurate than the others, but because it’s the one used in almost every major vitamin D study, on which the recommended blood levels for clinical efficacy are based.

Therefore, in order for any other testing method to offer clinically relevant results, the test values must agree with DiaSorin RIA results, since those were used to establish the recommended levels.

Vitamin D status is measured by looking at blood levels of 25-hydroxyvitamin D3. There are three common methods used for measuring vitamin D3:

1. LC-MS/MS – This test measures 25-hydroxyvitamin D2 and D3 separately
2. RIA (DiaSorin) -- Developed in 1985, it accurately measures total 25-hydroxyvitamin D (It does not separate D2 and D3)
3. Liaison (DiaSorin) --  a more recently developed automated immunoassay by DiaSorin that has largely replaced the RIA

The LC-MS/MS (liquid chromotatography-mass spectrometry) method is the preferred method for many labs, including the Mayo Clinic, Quest Labs, Esoterix, ZRT, and others, while Liaison is favored by other testing labs like LabCorp.

Recent developments in 2008 have made it clear that there are irregularities in the values obtained from the different testing methods. Although results from any of the three assays may be analytically accurate, they might not be clinically accurate, which is, ultimately, what matters.

Since the DiaSorin assay (RIA) was used in the major clinical studies that led to the recommended vitamin D levels, any lab using the LC-MS/MS  method need to make sure their test correlate with the RIA test values in order to accurately determine your vitamin D status.

WARNING: Your Lab Can Give You the WRONG Results!

It recently came to our attention that while the test Quest uses was analytically accurate, it gives vitamin D values that are consistently about 25-40 percent higher than the DiaSorin assay.

What does this mean?

If you are using Quest labs you are getting FALSE reassurances that your levels are accurate and you may even stop or discontinue treatment thinking that you are in the toxic range when, in reality, you still need more vitamin D.

Some labs, such as ZRT and the Mayo Clinic, have recognized the severity of this problem and have already calibrated their LC-MS/MS results against the DiaSorin RIA values -- in order to be clinically applicable --  whereas Quest has failed to do so. 

This is a serious problem since Quest probably runs the most vitamin D assays of any lab in the country.

Therefore, it’s imperative that you find out if your lab has performed the appropriate recalibrations against DiaSorin’s assays. Otherwise your vitamin D levels may be vastly overstated, in some cases by as much as 40 percent, meaning you may get the green light that your levels are fine, when in fact you are deficient, or perhaps even dangerously low.

The single biggest concern in this area is Quest Labs as their lab is reporting results as much as 40 percent higher than those found with the DiaSorin assay. That means, if you are seeking to obtain levels similar to those that have been confirmed optimal in the scientific literature, you will be falsely reassured by their test results.

At this point in time Quest has NOT recalibrated their test values to be aligned with DiaSorin, and it appears unlikely that they will do so anytime in the near future. Making matters worse, Quest is currently doing over 500,000 tests a month -- much of this increase has occurred over the past year -- and the consistent reports we are getting from the field is that many split samples being sent to them are coming back widely different, indicating a lack of consistency and quality.

The LC-MS/MS is clearly a highly accurate test, but only in the hands of experienced technicians who have the time to do the test properly, and only if it’s calibrated against the RIA.

Liaison, which is a more recently developed DiaSorin test that renders clinically accurate results, is also a much more accurate testing method for high volume throughput of tests, and does not depend as much on lab technician’s expertise. LabCorp uses this method, which makes them better able to handle large volumes of tests without sacrificing clinical accuracy or worrying about the qualifications of the staff.

I strongly recommend using LabCorp for these reasons until Quest can guarantee accurate, usable results.

How to Dose Your Vitamin D Once You Know Your Levels

Vitamin D is a fat soluble vitamin and can be quite toxic. Once you have vitamin D toxicity you can't easily turn it around, which is why I always recommend getting your levels checked prior to taking oral vitamin D supplements.

Overdosing on vitamin D from sun exposure however, is highly unlikely as your body has a built-in “failsafe” feedback loop, which will tend to shut down production when your levels are healthy. This is why I discuss getting optimal sun exposure, as opposed to lots of sun exposure. You know you’ve had enough once your skin turns the lightest shade of pink. Beyond that you’re only increasing your risk of getting burned, which can cause skin damage.

So, be very careful when using oral vitamin D therapy and make certain you have your blood levels checked. Many of you may choose to ignore this warning, but I am telling you in no uncertain terms, that while vitamin D has enormous potential for improving your health, it has significant potential to worsen it, if you use it improperly.

For safety purposes it is advisable to optimize your vitamin D levels only with the help of a trained health care professional. The exact protocol to optimize your vitamin D levels is described in Krispin Sullivan’s book Naked at Noon. The book has far more information than this brief review, and  further highlights the importance of testing.

The provocative headline is actually quite accurate though, as many people, especially with dark skin, would best benefit from exposing as much skin as possible to the sun (naked) as long as they don’t get burnt. This is in stark contrast to the approach most people take.

Some of Sullivan’s vitamin D research is also available on her Web site. Krispin Sullivan and I share the same passion--seeking to help large numbers of people regain their health with inexpensive nutritional therapies. She has researched this subject for a number of years and, to the best of my knowledge, is one of the most experienced clinicians in this area. She has provided me with much of the foundational background for this review, and I am very grateful for her willingness to bring me up to speed in, not only this area, but also omega-3 nutrition, and vitamin K.

Sunlight Is Your Ideal Source of Vitamin D

Ideally, the best place to get vitamin D is from your skin being exposed to the UV-B that is in normal sunlight. Vitamin D from sunlight acts as a pro-hormone, rapidly converting into 25-hydroxyvitamin D, or vitamin D3.

Unfortunately, the amount of sun reaching most of the U.S. is only sufficient to generate a healthy vitamin D response for far less than half the year.

Most people don't live far enough south or high enough in the mountains to allow enough Ultraviolet (UV) -B to reach their skin. So, for those times of the year when access to the proper amount of sun is not possible, you will want to consider an oral form of vitamin D. A high quality cod liver oil is probably your best choice, as it also supplies vitamin A, which helps limit vitamin D toxicity. It also contains beneficial omega-3 fats.

Ultraviolet-B Is What Generates Vitamin D in Your Skin

UV light is divided into three bands, or wavelength ranges, which are referred to as UV-A, UV-B and UV-C.

UV-B is sometimes called the "burning ray." It's the primary cause of sunburn caused by overexposure to sunlight. However, UV-B sunlight also produces vitamin D in your skin. The amount produced depends on exposure time, latitude and altitude of location, season, amount of skin surface exposed, and skin pigmentation.

UV-B also stimulates the production of MSH, an important hormone in weight loss, energy production, and in giving you that wonderful tanned appearance.

However, UV-B does not penetrate very deeply into your skin. The darker the pigmentation or more tanned your skin, the less UV-B penetrates. Other things that influence UV-B penetration include window glass and use of sunblock. Window glass allows only 5 percent of the UV-B light range that produces vitamin D to get through your home or car. Sunblock can block UV-B penetration drastically or entirely.

The timing of your sun exposure is also a major factor. Sun exposure must take place when UV-B is present. The actual dosing of your sun exposure is quite complex, since it involves knowing the amount of UV-B present, and is dependent on your skin color.

The amount of UV-B is not a constant. It is a major variable and is influenced by a number of factors:

• Latitude -- the further north you are the less UV-B there is
• Time of Year -- virtually none available in winter in continental U.S.
• Clouds -- can block UV-B
• Pollution -- smog and ozone can block UV-B
• Altitude -- the higher up you are, the more UV-B reaches you
• Person’s age – elderly have substantially less efficiency at producing vitamin D
• Skin pigmentation – darker skin takes longer to acquire UVB to produce vitamin D

It is important to know your level of UV-B exposure. Unlike the typical American strategy “more is better,” that is not the case for UV-B exposure. Longer exposure will not increase vitamin D production, but will increase the danger of skin damage and possible skin cancer.

Major Caution: Avoid Sunburn

It is important to stress that you should never get burned and should only implement sun exposure very gradually. While we all benefit from regular exposure to the sun, it is important to recognize that you should always limit your exposure so that you avoid getting burnt. Sunburn has been clearly related to an increased risk of skin cancer.

Interestingly, if you avoid getting sunburned yet have regular sun exposure, you will have a decreased risk of the dangerous form of skin cancer, melanoma. Optimizing your sun exposure in this way also reduces your risk of 16 other common cancers!

However, dermatologists will seek to frighten you about sun exposure. Please remember that we were all designed to have regular sun exposure. It is very similar to water. Just because you can drown while swimming, doesn't mean you should never drink water or swim in it. Similarly, as long as you avoid sun exposure that will cause burning, it will help improve your health.

It is a complex issue though. Skin cancer is largely related to the over-abundance of omega-6 oils consumed in the U.S. When sunlight hits these fats it can convert them to cancer-causing molecules, and if you are not healthy, cancer can develop. I recommend reviewing  the following article for more information:

• Does Too Much Sun Really Cause Melanoma?

This cancerous transformation doesn't happen with omega-3 fats. So, changing the ratio of omega-3 to omega-6 oils in your diet is one the keys to prevent this. The best source of omega-3 fat is krill oil.

Remember: Sunburn Has NO Health Benefits

It is also important to point out the obvious. Fair skinned individuals need far less exposure to receive their dose of sun to produce vitamin D. Lighter skin allows for greater penetration of UV-B, leading to higher levels of vitamin D.

African Americans however,  need considerably more sun to generate vitamin D. This is one of the reasons why breast- and prostate cancer rates are so much higher in Africans who live in temperate climates. They just aren't able to get enough sun to generate vitamin D. In fact, in the Northern U.S. cities, they will find it impossible to get adequate vitamin D from sunlight in any season.

Elderly individuals will also have a great difficulty getting enough vitamin D from sun exposure, because an enzyme in their skin decreases with degenerative aging and, as a result, their skin has a limited capacity for producing vitamin D.

As I said earlier, it is impossible to get vitamin D toxicity from too much sun exposure. Your body just won't let it happen. That is why receiving your vitamin D from the sun is the best option whenever possible.

Remember, ultraviolet exposure beyond the minimal dose required to produce skin redness, does not increase your vitamin D production any further.

An equilibrium occurs in white skin within 20 min of ultraviolet exposure, at which point further increases in vitamin D is not possible, because the ultraviolet light will actually start to degrade the vitamin D.

It can take 3-6 times longer for darker pigmented skin to reach the equilibrium concentration of skin pre vitamin D. However, skin pigmentation does not affect the amount of vitamin D that can be obtained through sunshine exposure.

A common misconception is that occasional exposure of your face and hands to sunlight is "sufficient" for vitamin D nutrition. Indeed, this exposure can provide 200-400 IU vitamin D during those months when appropriate sunlight is available, but for most of us this is an absolutely inadequate exposure to move vitamin levels to the healthy range of 45-50 ng/ml.

What to Do in the Winter

Ideally it would be best to relocate during the winter to a subtropical location where you will have access to plentiful solar radiation.  In the U.S. this would mean Florida, California, and Hawaii.  Interestingly, Hawaii has the top longevity rate in the U.S. Residents of the state live, on average, more than five years longer than those on the mainland.

Realistically not many will be able to relocate during the winter months.  An alternative would be to frequent tanning salons that use safe equipment. We have identified a database of them for your review. 

For the ultimate convenience though, you can use a safe home tanning bed like the Sun Splash.

If relocating in the winter or using tanning beds does not appeal to you, then you will want to consider an oral form of vitamin D.

Cod Liver Oil

It is important to know that if you have sub-tropical or summer sun exposure on your skin it will be wise to avoid any oral vitamin D supplementation unless you regularly monitor your vitamin D blood level. However the vast majority of people in the U.S. cannot possibly receive enough UV-B to generate optimal levels of vitamin D from September to mid-April.

Please also remember that just because it is sunny and hot outside, it is absolutely not an indication of the amount of UV-B l  present. If your latitude is above 30 degrees north or below 30 degrees south, you will likely benefit from vitamin D supplementation from September to mid-April.

If you don't know the latitude of your city you can use a latitude finder. If your latitude is lower than 30 degrees, then you have access to good sunshine and may not need oral vitamin D supplementation.

Your best choice for obtaining supplemental vitamin D3 would be to use a high quality cod liver oil. My research suggests Carlson's is one of the best tasting brands on the market and it can be obtained in most health food stores. If you have trouble finding it you can find it in our online store.

The optimal dose is about one teaspoon for every 50 pounds of body weight. However you should not take more than one tablespoon per day unless you are monitored by a natural medical physician.

This will not only provide you, the average 150 pound adult, with 2,000-3,000 units of vitamin D but  will also provide you with vitamin K, which is an essential co-factor in building strong bones. Cod liver oil also contains natural vitamin A  to support your immune system, and the oil is full of the beneficial omega-3 fats that nearly all of us are deficient in.

Additionally, there may be a protective benefit of vitamin A in limiting high calcium levels from vitamin D. (Johansson S, Melhus H. Vitamin A antagonizes calcium response to vitamin D in man. J Bone Miner Res. 2001 Oct;16(10):1899-905)

What to Do If You Have a Tough Time with Cod Liver Oil

Some people will have a difficult time digesting cod liver oil. If this is the case, try taking it on an empty stomach. You can start with small quantities and build up. If you do not use Carlson cod liver oil, there is a chance that the cod liver oil may be rancid. If it’s rancid it will not taste good and will have a "fishy" odor or taste. If this is the case, do not use the cod liver oil--the fats are spoiled. If you can't take or tolerate cod liver oil you will need some source of omega-3 fats.

Why  Eating Fish Just Won't Cut It Anymore

We have irreversibly polluted the environment by burning coal for electricity, and there is more than enough mercury in the waters of the world to contaminate virtually all  fish.

Even the conservative U.S. government warns pregnant women to avoid eating fish, since 60,000 kids are born with brain injuries from that mercury exposure every year. Farm raised fish do not avoid the problem--they still contain mercury and are in fact even worse since they are high in omega-6, not omega-3, from being fed corn.

Mercury is not oil soluble and therefore is not present in cod liver oil, so the problem of mercury toxicity is avoided.

Milk does provide vitamin D, but only about 250 units per 8 ounces. So, you’d have to drink a half-gallon per day to receive enough vitamin D from this source. There are a  number of reasons you should avoid drinking milk to stay healthy.

Please remember that it is best to have your levels regularly checked as supplemental vitamin D in certain clinical settings can be toxic.

Vitamin D Toxicity

First, let me state that there are two types of vitamin D supplements: vitamin D3 (cholecalciferol), which comes from fish oil, and plant source D2 (ergocalciferol), which is found in fortified foods and some supplements. D2, found in plants and made active by irradiation, is less biologically active.

Vitamin D3 is found in eggs, organ meats, animal fat, cod liver oil, and fish. It is the equivalent to the vitamin D3 formed on your skin from UV-B. You should stay away from the synthetic D2 as it has been shown to be toxic at the higher dose ranges.

You will only want to use vitamin D3 (cholecalciferol).

There are additional reasons why vitamin D2 has a greater potential for harm. First, vitamin D binding protein has a weaker affinity for the vitamin D2 metabolites than vitamin D3. Second, unique, biologically active metabolites are produced in your body from vitamin D2, but there are no analogous metabolites derived from vitamin D3.

There is no doubt that vitamin D2 is a synthetic analogue of vitamin D, with different characteristics. But it is inappropriate to regard vitamin D2 as a vitamin. Future research into the toxicity of vitamin D needs to focus on vitamin D3 as being something distinct from vitamin D2, for which almost all our current toxicity data relate to.

People Who Should Avoid Vitamin D

If you have sarcoidosis, tuberculosis, or lymphoma, it would be best for you to avoid oral vitamin D supplementation based on this test. It is recommended that you perform the 1,25(OH)D test before you supplement with any sun exposure or oral vitamin D as it is a better indicator in people with this health challenge.