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Vitamin D: A Sufficient Blood Level is Necessary for Optimal Health


vitamin DVitamin D: A Sufficient Blood Level is Necessary for Optimal Health

by Patricia E. Reykdal and Donald L. Smith. 11/26/2008

Vitamin D knowledge has undergone a fascinating evolution over the years. First, there was the general understanding that deficiency of this secosteroid hormone was the cause of the childhood disease known as rickets and later, it became known as the key to good bone health; now, there is an acknowledgment that vitamin D is necessary for humans to maintain optimal health and wellness-to the point at which some consider vitamin D to be a "miracle substance" that prevents a number of diseases, including various cancers, coronary heart disease, diabetes and multiple sclerosis, as well as several autoimmune and neurological diseases. Let's take a look at the history of vitamin D:

From Rickets To Optimal Health
sun to boneIt took 250 years from the time rickets was identified until it was understood that the cause of this bone-thinning disease was the direct result of pollution that prevented people from being exposed to ultraviolet radiation. It took another 30 years before scientists made the connection between UVR exposure and the production of vitamin D in the human body-and still several more years before a supplemental form of this important substance was developed. Until then, the only vitamin D supplement was cod liver oil, a substance that we now know can cause vitamin A toxicity. Sunlight, sunlamps and vitamin D supplements were used for the following 70 years to treat rickets and to prevent other bone diseases such as osteomalacia and osteoporosis.

A little more than a decade ago, vitamin D researchers began to discover more about the nature of vitamin D-mainly, that it went beyond simply aiding healthy bone development to preventing a number of diseases (all of which have a high incidence and mortality rate). These diseases include cancer (especially, breast, colon and prostate cancer), coronary heart disease, diabetes and multiple sclerosis, as well as several autoimmune and neurological diseases. In addition, researchers learned that more than 200 different cell types in the body have the ability to convert 25-OH-D into the biologically active form of vitamin D (1, 25-OH-D).

Authors' note: Keep in mind that a sufficient blood level of 25-OH-D is required for either individual cells or the kidney to synthesize the active form of vitamin D, 1, 25-OH-D.

So, what lies ahead? Well, although the knowledge about vitamin D gained over the past 10 years has been highly significant, the developments over the next decade will be even more important. Scientists expect to increase their knowledge about the role of vitamin D in cellular signaling (the process in which the cells in our body "talk" to each other) as they learn more about the role of the vitamin D receptor (VDR). Specifically, we believe that the next vitamin D breakthrough will be the measurement of intra-cellular vitamin D (the amount of 1,25-OH-D within the cell), which bodes well for a premise we put forth in our September article, "Melanoma: Coincidental Correlation Does Not Prove Causation."

(Quick recap: Basically, we said that melanocytes cannot not transform into a melanoma unless an insufficient level of the active form of intra-cellular vitamin D exists. That is because a sub-optimal level impedes the signal telling the "mother" melanocyte cell to stop dividing, reattach itself to the basement membrane and reestablish a new epidermal melanin unit (EMU); thus, the cell becomes cancerous. A sufficient intra-cellular level of the active form of vitamin D, on the other hand, prevents the "scrambling" of that signal.)

All of these developments regarding our understanding of vitamin D beg two questions, though. First, what is the optimal blood level of vitamin D to maintain good health? Second, what is the best way to achieve that level?

Optimal Vitamin D Blood Levels
A recent article titled, "Diagnosis and Treatment of Vitamin D Deficiency," by John Cannell, Bruce Hollis, Michael Zasloff and Robert Heaney, states that "treatment of vitamin D deficiency should be sufficient to maintain levels found in humans living naturally in a sun-rich environment, that is, greater than 40 ng/ml (i.e., greater than100 nmol/L) year-round." Other authors have recently called for a target level of 48 ng/ml (i.e., greater than 120 nmol/L), and readers of this column know that we have long advocated maintaining a level of greater than 60 ng/ml (i.e., greater than 150 nmol/L). But even those suggested levels might be too low-we may need to revise our suggestion to say that a target level of 80 ng/ml (i.e., 200 nmol/L) or perhaps 100 ng/ml (250 nmol/L) should be adopted.

Maintaining Optimal Vitamin D Blood Levels
In their article, Cannell, Hollis, Zasloff and Heaney state that "three treatment modalities exist: sunlight, artificial UVB radiation or supplementation" and that while all three treatment options have potential risks and benefits, the "benefits of all treatment modalities outweigh potential risks and greatly outweigh the risk of no treatment."

sun for Vitamin DThe question that is being ignored by vitamin D researchers is whether supplemental vitamin D has the same "biological activity" as UVR-induced vitamin D or does UVR-induced vitamin D have beneficial effects not found when the supplemental form is used? In other words: Does Mother Nature know best?

Cannell, Hollis, Zasloff and Heaney say that "despite robust skin production [of vitamin D], vitamin D toxicity cannot occur from skin production." On the other hand, there is a significant risk of vitamin D toxicity when supplementation doses of 5,000 to 10,000 IUs per day are administered-a level many vitamin D experts consider necessary in order to maintain optimal blood levels of vitamin D. Moreover, it must be kept in mind that, while many in the scientific community believe that high doses of supplemental vitamin D are safe, there are no long-term studies regarding the safety of doses higher than 400 IUs per day to support that belief.

Frankly, it is time for a fair and balanced long-term prospective study to be commissioned by the National Institutes of Health to ascertain whether supplemental vitamin D, UVR-induced vitamin D or perhaps a combination of the two is best able to reduce the impact of vitamin D deficiency and to help the public achieve optimal health and wellness.

Patricia E. Reykdal and Donald L. Smith operate the Non-Ionizing Radiation Research Institute in Tucson, Ariz. They have written many articles promoting the benefits of controlled ultraviolet-radiation exposure (CURE). You can e-mail comments or questions to


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