Understanding Vitamin D…Part 1

There are two kinds of Vitamin D that we can take or get from foods, those are known as D2 and D3.  A number of years ago a study was done on how well we absorb D2 and D3 and it was found that we absorb D3 slightly better than we do D2[1].  This led to a wide-spread false belief that D3 is better for us than D2.  Now most people would not have any problem with that assumption, however, if you happened to be a vegetarian then the commonly held belief might cause you to do a double take because D2 comes from plant sources whereas D3 comes from animal sources and we are only talking about a slight absorption difference.  Unfortunately, that false belief from a decade ago has led to an even more false belief that D2 is somehow not-active and D3 is active which is completely (sorry folks) false on its face.  However, in order to understand just how untrue and uninformed this belief is, you’d have to know a thing or two about Vitamin D which we will cover in this article. 

 

Vitamin D is synthesized, or “created,” by animals and some plants in response to the sun’s light and, upon its creation, then goes through a multi-stepped process in order to be used.  Vitamin D2’s true chemical name is Ergocalciferol, and Vitamin D3 is, Cholecalciferol, and I invite you to check the labels on your own Vitamin D bottles (or those at the store) in order to personally verify that your Vitamin D2 is truly “Ergocalciferol,” and your Vitamin D3 is truly “Cholecalciferol.”  You see, this is an important distinction that many well-meaning exerts (including researchers and well-loved doctors) make that perpetuates the false belief that either of these are in “active” form. 
 

 



So now that you know that Vitamin D3 is, in fact, Cholecalciferol, the next step is understanding how the body utilizes Cholecalciferol.  However, it is also important to understand that we also make Cholecalciferol.  We do that from Cholesterol (that we also make), or rather a part of it called, “7-dehydrocholesterol.”  The process takes place within the fat under our skin; in response to the UV rays from the sun or lights, we turn 7-dehydrocholesterol into Cholecalciferol.  From there, whether we make the Cholecalciferol in our skin or whether we take it as a pill or get it from foods, the Cholecalciferol enters our blood stream where it is then converted into “Calcidiol” which then finds its way into our kidneys and is converted into “Calcitriol,” the ONLY true physiologically “active” form of Vitamin D.  In other words, whether we make it ourselves from the sun or take it as D3, it still has to go through an additional 2-step process in order for our body to use it.  Or, in still other words, in order for it to become “active.” 

 

It always shocks and disappoints me when the doctors and experts that I love and respect make this critical error in calling D3 active, and it never fails to sadden me when vegetarians are discouraged from taking D2 which, despite not being absorbed as well, is still absorbed well enough to be a viable alternative to D3 which is derived from animal sources or from irradiation.

 

I hope that helps you understand a little more about Vitamin D.  In the next part, we will take a deeper look into Vitamin D testing and the implications it has to all we think we know about Vitamin D.

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[1] Evidence that vitamin D3 increases serum 25-hydroxyvitamin D more efficiently than does vitamin D2. H M Trang, D E Cole, L A Rubin, A Pierratos, S Siu, and R Vieth, American Journal of Clinical Nutrition October 1998 vol. 68  no. 4  854-858

Understanding Vitamin D…Part 1a

Understanding Vitamin D…Part 2 Testing

In the first part, we looked at the how the body makes vitamin D and deals with the vitamin D3 that we take.  In this part, we will take a deeper look at Vitamin D testing and the implications that it has on our current understanding of Vitamin D and its role in our health and wellbeing. 

 

When your doctor or practitioner runs a Vitamin D test for you, it is likely that they ran what is known as the 25,D test.  The 25,D tests for D2 (non-active plant based ergocalciferol) and D3 (non-active animal based cholecalciferol) which it then totals to give you your Vitamin D level.  This is the basis (and often the sole basis) for the assumption that one is low in Vitamin D.  It is also the sole basis in the majority of studies on Vitamin D and its effect on one’s health and illness.  However, as we looked at in part 1, all this shows is the amount of non-active, or storage form, of Vitamin D.  This is sort of like looking in one’s freezer and making an assumption of whether or not they are getting enough to eat.  What it does not do, is look at one’s table and see if there is food on it. 

 

It is often believed, in the medical community, that if there is enough of the storage form of something that 1) the body is properly converting it into the active form; and 2) that it is doing so in sufficient quantities.  For example, in measuring thyroid function, they often only test the pituitary’s request for thyroid hormone (TSH) or, if they are progressive, test only the storage form of the thyroid hormone (T4) assuming that the body is properly converting it and that it is doing so in sufficient quantities.  Only rarely, if ever (and often only by patients pushing for it), do they test the active form of the thyroid hormone (T3). 

 

On one hand, this practice allows for the fact that no one really knows the deeper ways of the body, or its logic for doing what it does, enough to draw any solid conclusions.  However, on the other hand, if one is having a problem then a closer look is warranted and, indeed, would be the only thing that could tell you whether or not you have a problem in this particular area.  For example, with the thyroid, a number of people have perfectly fine levels of TSH and T4, but are not making enough of the active hormone T3.  If you only looked at the TSH and T4 you would never know this and the implication is that the person would continue to suffer low thyroid levels and be, ultimately, denied access to treatment for those low levels and that could profoundly improve the quality of their life. 

 

The same issue as for the thyroid is also true of Vitamin D (yet another endocrine hormone).  When they test one’s Vitamin D levels they use the 25,D test which only looks for the non-active storage form of Vitamin D (like looking in one’s freezer).  The 25,D test does NOT look at the active form of Vitamin D (look at one’s plate).  This has huge implications, not only to our own understanding of the role of Vitamin D, but also in that it potentially invalidates the majority of studies on the subject.  My hope is, of course, that the medical community and researchers begin to realize the inherent issue in the way we are currently doing things.  For example, a large amount of the studies done on Vitamin D are done on people with chronic illness.  However, and even though the medical community suspects that autoimmune conditions likely arose from some underlying infection that potentiated the immune system, and that bacterial infections (even low grade ones) increase the activity of the enzyme CYP27B1 that converts 25,D (D3 - cholecalciferol) to 1,25 D (calcitriol), therefore producing too much 1,25 D (calcitriol) and also creating misleadingly low 25,D (D3 - cholecalciferol) levels.  As well, those with certain genetic mutations (ones that you would probably never know about) likewise, up-regulate the enzyme CYP27B1 which then over-converts D3 (25,D) into calcitriol (1,25 D).  Either one of these factors creates misleadingly low 25,D levels and the assumption that they are low Vitamin D.  However, these factors also create either ideal, or too high, levels of 1,25 D (the active hormone).  In other words, a majority of the Vitamin D studies on those with chronic illness, are likely not-low, but instead too high levels of the active hormone, but they would never know because they do not realize that there is an inherent issue with the 25,D test (nor do most other people know).  And the belief that those with low non-active 25,D levels should (and do) supplement only exacerbates this issue causing an even greater situation if the person has too high levels of active (1,25 D) Vitamin D. 

 

Therefore, for those who are sick or who are told that they have low 25,D levels, should get  dual Vitamin D testing done wherein both 25,D and 1,25 D are tested to ensure that they are, in fact, low in active 1,25 D before taking Pre-Vitamin D3.  If one has low 25,D and ideal (middle of the range) or high (higher than the middle of the range), this is known as the Vitamin D Reversal Pattern and warrants further investigation as to why.  For example, do you have some chronic underlying condition that you didn’t know about? 

 

I hope that helps you understand Vitamin D a bit better.  In the next part, we will take a deeper look at how high levels of the active (1,25 D) hormone can adversely affect your health.