Once again, a negative vitamin D paper has received much attention from the media, and once again, public health takes a few steps backwards.
In the paper, “Vitamin D Deficiency — Is There Really a Pandemic?” the authors argued that research repeatedly misinterprets the prevalence of vitamin D deficiency by quantifying those who are vitamin D deficient with the Recommended Dietary Allowance (RDA) corresponding sufficient level, opposed to the Estimated Average Intake (EAR) level.
The RDA suggests a daily intake of 600 IU per day for those who are of the ages 1-70 years and 800 IU per day for persons older than 70. These intakes correspond to achieving a serum vitamin D status of 20 ng/ml. (Although, in the past few years, the calculation of the RDA has been under scrutiny and criticized for falling for using faulty statistics, which have been shown by multiple papers.)
The EAR is the intake level for a nutrient that meets the needs of half of the population. For vitamin D, this level is set at a meager 400 IU daily for persons 1-70 years of age and 600 IU daily for persons older than 70. These intakes were created to reach a 25(OH)D level of 16 ng/ml.
The paper is summarized with the following excerpt,
“Many studies establish “inadequacy” using the RDA, though it is actually at the upper end of the spectrum of human need. Clearly, this approach misclassifies as “deficient” most people whose nutrient requirements are being met— thereby creating the appearance of a pandemic of deficiency.”
Remember, both the RDA and the EAR levels reflect the vitamin D concentrations needed to maintain adequate bone health. Therefore, both levels neglect much of the research that has been published in the past decade or so, illustrating the benefits of vitamin D above and beyond bone health. For this reason, one could argue that many of the studies assessing the prevalence of vitamin D deficiency, in fact, underestimates the prevalence of vitamin D deficiency opposed to overestimates, since we now know that vitamin D plays an important role in strengthening the immune system and reducing inflammation.
Here are just a few of the studies that support the need for vitamin D levels above 20 ng/ml for optimal health:
- Serum 25-Hydroxyvitamin D Concentrations >40 ng/ml Are Associated with >65% Lower Cancer Risk: Pooled Analysis of Randomized Trial and Prospective Cohort Study
- Maternal Versus Infant Vitamin D Supplementation During Lactation: A Randomized Controlled Trial
- Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies
- Serum 25-hydroxyvitamin d and risk of lung cancer in male smokers: a nested case-control study
- Association of 25-hydroxy-vitamin D levels with semen and hormonal parameters
- Depressed adolescents in a case-series were low in vitamin D and depression was ameliorated by vitamin D supplementation
- Vitamin D metabolism, functions and needs: from science to health claims
- Relationship between vitamin D status and left ventricular geometry in a healthy population: results from the Baltimore Longitudinal Study of Aging
The idea of requiring a vitamin D status near 40 ng/ml can be explained quite simply. Humans evolved outdoors in the sun and near the equator, synthesizing robust quantities of vitamin D in the skin. Research has shown that lifeguards, farmers near the equator and sun dwelling hunter gatherers maintain blood levels between 40-80 ng/ml on sun exposure alone. As Dr. Cannell once said, “Humans make thousands of units of vitamin D within minutes of whole body exposure to sunlight. From what we know of nature, it is unlikely such a system evolved by chance.”
Today, we rarely go outside during the week due to our 9 am to 5 pm jobs, and many smother themselves in sunscreen when they do. Therefore, the vitamin D deficiency pandemic is somewhat intuitive when you begin thinking about it.
However, for argument’s sake, let’s pretend that vitamin D does not possess any extra-skeletal benefits, and its sole purpose is to improve bone health.
Henry Lahore, Vitamin D Wiki’s writer and founder, created a wonderful summary, essentially stating that research looking at vitamin D for bone health also aligns with a vitamin D status requirement greater than 20 ng/ml. He shared the following studies:
- Bone fractures reduced by a minimum of 800 IU vitamin D and Calcium – meta-analysis March 2014
- Professor who concluded that vitamin D (800 IU) does not help bones got 324,000 dollar prize- November 2015
In his summary, Mr. Lahore also pointed out,
“[The paper reports], “Less than 6% are deficient in vitamin D levels <12.5 ng per milliliter” Their reference is the IoM report – that data for which is now 8 years out of date.”
Lastly, for argument’s sake again, let’s pretend that half of the population only requires 16 ng/ml, which is quite a stretch from the truth.
Dr. Steve Blake, a faculty member of Nutritional Biochemistry at Hawaii Pacific Neuroscience, provided the graph shown below, which illustrates the most recent data of Americans who do not receive the EARs of vitamin D, along with other vitamins and minerals. The graph was obtained from the analysis, “Foods, Fortificants, and Supplements: Where Do Americans Get Their Nutrients?” The paper assessed the intakes of micronutrients derived from all sources (dietary supplements, naturally occurring, fortified and enriched) to compare the usual intakes of Americans to the Dietary Reference Intake for Americans. The data was gathered from NHANES 2003-2006, which consisted of 16,110 individuals.
The graph clearly illustrates that 70% of the U.S. population does not meet the EAR, the intake estimated to achieve 16 ng/ml in only half of the population. One cannot look at this graph and still question the existence of the vitamin D deficiency pandemic.
The Vitamin D Council team, again, urges its readers to critically assess papers and media headlines before accepting them as facts. We believe change begins with you, the individuals who care and are passionate about public health. Together, let’s move forward and continue disseminating information on vitamin D and safe sun exposure for human health.
Tovey, A. & Cannell, JJ. Are we currently amid a vitamin D deficiency pandemic? The Vitamin D Council Blog & Newsletter, 2016.