For years we have warned readers that liberal use of sunscreen could prevent the body from making adequate amounts of vitamin D. We didn’t make that up. Dr. Michael Holick is an expert on vitamin D. During a radio interview many years ago he expressed concern that the widespread use of high SPF sunscreens could interfere with vitamin D formation.
In a paper published in PLoS One (Jan. 29, 2016) Dr. Holick and his colleagues note that:
“…strict UV-protection promotes vitamin D deficiency, that is associated with an increased risk for and an unfavourable outcome of many diseases.”
The authors go on to say:
“To avoid direct sun exposure widespread sunscreen use is implemented. However, was not fully appreciated was that sunscreens are designed to efficiently absorbed radiation in the UVB range; an SPF of 30 absorbs 97.5%. The unintended consequence is that this radiation is also responsible for the cutaneous production of vitamin D. As a result an SPF of 30, properly applied, reduces the capacity of the skin to produce vitamin D by 97.5%.”
Having spread this message, it is not surprising that our podcast listeners and readers would be concerned about high SPF sunscreens. Here is the latest question in that regard.
Do Sunscreen Block Vitamin D Formation
Q. You’ve written about sunscreen, but I haven’t seen you address the topic that worries me most. By using sunscreen every day, you may limit the amount of vitamin D formation your body can make.
Some studies suggest that lower vitamin D contributes to a greater risk of cancer. When scientists study sunscreen, they should monitor vitamin D in participants. Has anyone done that?
A. Yes! And the most recent research suggests that using SPF 15 sunscreen that also blocks UVA radiation does not prevent vitamin D formation (British Journal of Dermatology, Nov. 2019).
We know this contradicts popular wisdom about sunscreen, but a review of the medical literature concluded that daily sunscreen application does not seem to interfere with skin vitamin D formation (British Journal of Dermatology, Nov. 2019). The studies in the review, however, used moderate SPF sunscreen (15) rather than the very high sun protection factor sunscreens (30 to 50) that are now popular.
What About High SPF Sunscreens and Vitamin D Formation?
The answer to this question remains unanswered. There is a surprising amount of information that is lacking about sunscreens. It was only this year that a study in JAMA (Jan. 21, 2020) confirmed that sunscreen ingredients can be absorbed through the skin and get into the blood stream.
The FDA still does not know whether such absorption represents a hazard. This is especially concerning for young children. You can learn more about this research and the potential problems of specific ingredients at this link.
Because we can now buy sunscreens with SPF numbers of 50 and higher, it is unclear whether such products will interfere with vitamin D formation. One way to find out is to be tested for vitamin D deficiency. If you do not feel like going to a testing lab to have your blood drawn, there are now home kits that allow you to send your blood sample in for analysis.
Learn more about vitamin D in our eGuide to Vitamin D and Optimal Health at this link.