Knowing Your Vitamin D Levels

credit: Instagram @lepekah

For early humans, most of their day was spent outside in the sun with copious amounts of UV-rays for vitamin D synthesis. Today, however, more and more people work indoors under artificial lighting. Even when people do spend time under the sun, many wear enough clothing or sunblock to prevent the production of Vitamin D. Vitamin D plays an important role in all tissues of the human body, so insufficient amounts may cause issues with the heart, brain, muscles and intestines. In fact, studies have shown a correlation between vitamin D supplementation and reduced inflammation, a decrease in cancer risk, and improved cardiovascular health.

Quick facts:

  • According to the National Institutes of Health, the recommended daily allowance for vitamin D is 600 IU.
  • A blood concentration over 30 ng/mL is generally adequate for healthy bones and correlated with overall health.¹
  • A 2009 study found that three quarters of U.S. teens and adults are deficient in the hormone.²
  • Worldwide, it’s estimated that nearly one billion people are deficient.

With varying combinations of lifestyles and diets, it can be difficult for individuals to determine if they are vitamin D deficient. The best way to tell if a person is getting enough of the essential hormone is through blood tests. By knowing their levels, individuals can take proactive measures to address inadequacies in their diets or start supplementation, if necessary.

How much is too much?

Dave Asprey, of the Bulletproof Executive, and WellnessFX CEO Jim Kean sat down recently to discuss the benefits of vitamin D and how to obtain optimal amounts of the hormone. When vitamin D is produced naturally by the body in response to sun exposure, the levels are regulated and controlled. Supplementing, however, creates very specific levels of the hormone, which may or may not be favorable for certain individuals. Recent studies have shown that supplementing too much vitamin D can actually reverse the beneficial effects and be detrimental to one’s health.³ The optimal intake level is called a “set point,” which is different for everyone. Learn more about set points and vitamin D supplementation from the video below.

As discussed in the video, vitamin D is correlated with blood levels of high sensitivity C-reactive protein, or hs-CRP, an important indicator for inflammation. High hs-CRP levels have been associated with risk of diseases such as cancer, dementia, cardiovascular disease and many other chronic diseases. Vitamin D deficiency usually means a high hs-CRP level, which subsequent supplementation can mitigate. However, researchers at Johns Hopkins University found that once vitamin D levels exceeded the lower level of what is considered normal, hs-CRP levels began to rise again.³

You can find out your own vitamin D set point with periodic testing of the hs-CRP inflammation marker using varying levels of vitamin D supplementation. For example, Jim Kean’s hs-CRP marker reading was on the cusp of inflammation. After increasing his vitamin D intake, testing showed a drop in his hs-CRP to a healthier reading. However, when he increased his vitamin D even further, his hs-CRP shot up to higher than before, pushing him into the inflammatory range. From these tests, Jim was able to find his personal prescription for vitamin D – his set point.


Vitamin D is important, not only for maintaining strong bones, but also for preventing disease. As our lifestyles and cultures have evolved, so have our methods for obtaining the essential compound. The only way to be sure if a specific regimen is right for an individual’s health is through periodic testing of vitamin D levels, monitoring of the hs-CRP inflammation marker and appropriate adjustments to diet and supplementation.

Get started with WellnessFX Baseline to measure your Vitamin D, inflammation and 28 other biomarkers of your health.



The posts on this blog are for information only, and are not intended to substitute for a doctor-patient or other healthcare professional-patient relationship nor do they constitute medical or healthcare advice of any kind. Any information in these posts should not be acted upon without consideration of primary source material and professional input from one's own healthcare professionals.