The Vitamin D Controversy Even Off The Radar Of Most Physicians

The recent inclusion of a blood test for Vitamin D, along with a lipid panel, had me wondering about the reason.  Then, a day later when the result came back from Labcorp and was designated 'Low' at 22.8 ng/ml I decided to do some research.  Even before the Covid pandemic erupted I had been taking 1,000 i.u. each day of Vitamin D - a vitamin that's been found crucial to avoid respiratory issues.  So how could this level be "low". 

 It didn't take long to discover an ongoing controversy between different elements of the medical community had been ongoing since at least 2010.   Added to this, we read from the NIH gov't websit:

Assessing vitamin D status by measuring serum 25(OH)D concentrations is complicated by the considerable variability of the available assays (the two most common ones involve antibodies or chromatography) used by laboratories that conduct the analyses [5,6]. As a result, a finding can be falsely low or falsely high, depending on the assay used and the laboratory. 

And also see the Table:

Where it is clear my level of 22.8 is in the healthy range,  I.e.  the second to last line showing:

≥ 20	ng/ ml Generally considered adequate for bone and overall health in healthy individuals

  Though the reference level (desired) starting point in the blood test indicated > 30 ng/ml. So what gives?  Some of the answers were uncovered in a Harvard Health Blog by Monique Tello, MD, MPH  who wrote:

 "In my practice, and in most, it is not uncommon to see a vitamin D level less than 20. When that happens, we tell the patient that they are deficient and recommend fairly aggressive replenishment, as well as ongoing supplementation. The majority of folks have a level between 20 and 40, in my experience, and this is corroborated by the IOM’s findings in that 2010 report.

But in 2011, the respected Endocrine Society issued a report urging a much, much higher minimum blood level of vitamin D. At that time, their experts concluded: "Based on all the evidence, at a minimum, we recommend vitamin D levels of 30 ng/mL, and because of the vagaries of some of the assays, to guarantee sufficiency, we recommend between 40 and 60 ng/mL for both children and adults."

So  there it is, the reason for the 'low' designation on my blood test for Vitamin D:  The Labcorp testers were going by the Endocrine Society level of at least 30 ng/ml needed for adequate health needs.  But as Dr. Tello goes on to point out:

A different opinion on the right target level of vitamin D is presented in an article titled "Vitamin D Deficiency: Is There Really a Pandemic?" published in the New England Journal of Medicine. In this piece, several of the leading epidemiologists and endocrinologists who were on the original IOM committee argue for a lowering of the currently accepted cutoff level of 20, stating that the level they estimated as acceptable was never intended to be used to define vitamin D deficiency. They feel that we are over-screening for vitamin D deficiency, and unnecessarily treating individuals who are perfectly fine.

Based on their analysis, a more appropriate cutoff for vitamin D deficiency would be much lower, 12.5 ng/mL. They examined a massive amount of data from the National Health and Nutrition Examination Survey (NHANES) for 2007 through 2010 and found that less than 6% of Americans had vitamin D levels less than 12.5. A cutoff of 12.5 ng/mL would most certainly eliminate the "pandemic" of vitamin D deficiency.

So  given I am significantly past the NE JM cutoff of 12.5 ng/ml it appears I can regard myself as definitely not Vitamin D deficient as the Labcorp result suggests.  Do I therefore hold steady at an intake or 1,000 i.u. a day or raise it? I believe I hold steady.  It's also interesting to note the work of Dr. Joel Finkelstein referenced in the same Harvard Blog.  He is the Associate Director of the Bone Density Center Center at Massachusetts General Hospital.  His research in the field has spanned 3 decades so he's no newbie to the field.  

He points out that from an evolutionary standpoint it makes no sense that higher vitamin D levels would be beneficial to humans.   As he related to the Harvard Medical Blogger:

"Vitamin D is actually quite hard to find in naturally occurring food sources.  Yes, we can get vitamin D from the sun, but our bodies evolved to create darker skin in the parts of the world that get the most sun. If vitamin D is so critical to humans, why would we evolve in this way, to require something that is hard to come by, and then evolve in such a way as to make it harder to absorb?"

His points are totally valid in evolutionary terms, which again makes the Endocrine Society's take seem more politically-based. After all, why would a species evolve to so critically depend on a substance that by nature is rare, hard to come by?   Further, a large segment of members evolving in a way - white skin - that makes it harder to absorb?  It makes no sense.  Given this I have to concur with Dr. Finkelstein's take that:

“Vitamin D has been hyped massively.  We do not need to be checking the vitamin D levels of most healthy individuals." 

Will someone in higher medical authority please relay the message to the Endocrine Society so they lower their vitamin D "healthy" level designations?  And while we're at it let's get the word out to the primary physicians who may order needless lab tests as well.