Science & Technology: Vitamin D (Vitamin D: How Much Is Enough)

The good news is that there is a virtual tsunami-flood of articles in scientific and mainstream media pointing out the health benefits of maintaining a sufficient vitamin D level. The not-so-good news is that almost all of those articles recommend taking supplementary vitamin D to resolve the pandemic of vitamin D insufficiency. The bad news is that only a few articles have told the public the truth—that UVR exposure is the best way to obtain vitamin D, and in only a handful of articles did the authors acknowledge that the best way to maintain a sufficient vitamin D level is utilizing the controlled ultraviolet radiation exposure (C.U.R.E.) that is available at a professional indoor tanning salon.

The fact of the matter is that we must continue, on behalf of the American public, to expose the vested-interest lies told by the sunscreen industry and the dermatology community—until all media routinely recommends the year-round use of C.U.R.E. to help resolve the pandemic of vitamin D insufficiency.

Even understanding this, we are left with a few questions:

• How much UVR exposure do you need to attain/maintain a sufficient level of vitamin D?
• How many days are required to attain/maintain a sufficient level of vitamin D when taking vitamin D supplements?
• How does stimulating vitamin D via C.U.R.E. compare to the use of vitamin D supplements?

Sufficiency. Not too many years ago, a level of vitamin D high enough to prevent rickets (>32 nmol/L) was considered to be sufficient. Then, anything above 50 nmol/L (and more recently 75-80 nmol/L) was considered sufficient for bone health. Now it is widely recognized that a number of diseases are “mediated” by vitamin D and, very importantly, that this secosteroid hormone (that’s right, vitamin D actually is a hormone, not a vitamin) is key to optimal cellular signaling. Given the ubiquitous nature of vitamin D, what is the level required to maintain sufficiency and, therefore, optimal health and well-being? Regular readers of this column know that we recommend maintaining a blood level of 150 nmol/L, and several vitamin D experts recently have recommended maintaining a level of at least 120 nmol/L. Since primates in the wild and outdoor workers maintain a level of 150-220 nmol/L, we continue to believe that Mother Nature intended us to maintain a year-round level of at least 150 nmol/L in order to fulfill all of the body’s requirements for vitamin D.

Supplements. The current Recommended Daily Allowance (RDA) for supplemental vitamin D is 200-600 international units (IU), notwithstanding the fact that most experts recommend between 1,000 and 2,000 IU each day, and one leading expert recently has recommended a minimum daily dose of 2,600 IU. The table on page 30 shows how many days it takes to go from a blood level of 50 nmol/L (i.e., the blood level found in most American citizens) to either 120 nmol/L or 150 nmol/L when taking a daily supplement.

As you can see, it takes 365 days to reach 120 nmol/L and 456 days to reach 150 nmol/L when taking a daily 1,000 IU vitamin D supplement; 183 days to reach 120 mol/L and 228 days to reach 150 nmol/L when taking a daily 2,000 IU supplement; and 140 days to reach 120 nmol/L and 175 days to reach 150 nmol/L when taking a daily 2,600 IU vitamin D supplement. It is important to keep in mind that several scientific studies have shown that vitamin D in supplement form has less potent biological activity than UVR-induced vitamin D.