Why Is My Vitamin D Low?

Vitamin D gets a lot of good press – and for good reason. In addition to its importance in bone health, it’s a major contributor to healthy immune function, it helps keep pain and inflammation in check, and is believed to protect against neurodegenerative disorders.

Because of its numerous contributions to good health, doctors will commonly recommend testing Vitamin D levels periodically for their patients and supplements and/or healthy sun exposure to keep levels in a healthy range.

But many people struggle to maintain normal Vitamin D levels despite substantial sun exposure and/or supplementation. There are a few common reasons for this.

First, Vitamin D supplement quality can vary greatly and the actual amount in a given supplement can be much less (or sometimes much greater) than is stated on the product label. It’s recommended that you use independently lab-certified products to avoid this issue.

Next, genetics and skin pigmentation can play a role, particularly when it comes to obtaining Vitamin D from sun exposure. Some people simply don’t produce as much Vitamin D from sunlight and/or may not convert it as efficiently as others to the active form that circulates in the bloodstream – the form that shows up on lab tests. People with more melanin in their skin don’t produce as much Vitamin D from sunlight as lighter-skinned individuals.

But there’s another extremely common issue that leads to Vitamin D deficiency that tends to be overlooked. Vitamin D, whether from supplements or sun exposure starts out as the D3 form, which as just mentioned, needs to be converted to the active form of Vitamin D. This conversion requires magnesium – a mineral that approximately 50% of Americans are deficient in.

Without adequate magnesium, Vitamin D is not efficiently converted to its active form, and may result in a situation where one tests low on Vitamin D despite heavy supplementation and/or extensive sun exposure.

I’ve discussed the importance of magnesium for brain function and recommendations for supplementation in another article (you can read it here).

Again, it’s also important to use independently-certified supplements to at least be reasonably sure you’re taking the amount you think you’re taking, whether it be Vitamin D, magnesium, or anything else. And if you have relatively dark skin, sun exposure alone may not always be enough to meet your Vitamin D needs.

But if you’ve tended to have low Vitamin D levels on testing that doesn’t seem to improve much with higher intake, I highly recommend you try adding some magnesium to the mix.

Until next time…

George F. Best, D.C.