It’s Q & A day today! I received this question from a patient just last week…
She was all about the use of sunscreen to protect her kids from getting sunburned, but was wondering if it might actually block vitamin D production? And if so, how long does she need to leave the kids without sunscreen? Is that even safe/worth the risk?
With the link between sun exposure and skin cancer, many of us (sadly) avoid the glorious sunshine. Or we can be found wearing clothes to cover our skin and lathered up with sunscreen everywhere else. Skin cancer risks aside, I myself being a fair skinned red-head have been very pro-sunscreen, it only takes one bad burn to know you don’t want to feel that again.
On the other hand, our bodies need vitamin D for healthy bones, cells, nerve, muscle and immune cell formation. We get vitamin D when our skin is exposed to sunlight. The sunshine converts inactive vitamin D into active vitamin D. No sun? No vitamin D.
In fact, vitamin D deficiency is so rampant in Canada, even Health Canada recommends every Canadian take a supplement! We are just assumed to be deficient due to our northern latitude on the planet. It's considered so "par for the course" in Canada that Canadian physicians have to justify running vitamin D screens on blood work by building a case for it… serum vitamin D costs anywhere from $30-$100 CAD depending on what province you are in, so unless you need it tracked as part of a specific health condition/treatment program, it’s considered a waste of healthcare (ahem, taxpayer) dollars.
So what is a Mom to do? Does sunscreen block vitamin D? Maybe we should be getting a little sun? And if so, how much? Let’s find out...
The short answer is Yes, it does… theoretically, anyway. Sunscreen works to prevent burns by blocking the UVB rays that are required for the production of vitamin D in the skin. No UVB means no vitamin D, or so the logic goes...
Australian researchers did a study tracking vitamin D levels in two groups - sunscreen wearers and non-sunscreen wearers. It seems after a full summer of exposure, they found no significant difference in serum vitamin D levels between groups. The reasons given for this seemingly strange result: differences in how much and how often the sunscreen was applied! (http://www.ncbi.nlm.nih.gov/pubmed/7726582)
Just to be sure, I scanned through some more recent research… it turns out, you can get some vitamin D even if you are wearing sunscreen in sunny places, but mostly because you’re not applying it “correctly”. Level of SPF, your frequency and your method of application are all factors to consider.
In Canada, if we used the sunscreen “correctly” as per this research, I suspect we may not get enough sun to “shine through” the sunscreen’s UVB protection to the level that would ensure we maintain vitamin D levels. (Especially so in St. John’s, the world's home of RDF.) I admit… this is my gut instinct on this. I’m open to reading more independent Canadian research if someone has it?
Well… that depends on your skin color. Melanin, the substance that makes skin “tan” or darker competes for the UVB rays along with the vitamin D.
In naturopathic medical school, I learned that if you are fair-skinned, your body can produce the amount of vitamin D it needs within 10- 20 minutes during peak hours (11 am – 3 pm). Darker individuals may need up to 25 mins of direct sunlight a day.
So what’s it gonna be? The skin cancer or a mild vitamin D deficiency? Um… obviously take the vitamin D deficiency. (I don’t want to hear anyone raise their hand for the skin cancer, even for argument's sake TYVM.) You can get a supplement to correct the low vitamin D, correcting skin cancer on the other hand...
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If you are not getting outside for longer than 20 minutes of fresh air per day, forget the sunscreen and vitamin D. Let’s talk instead about why you aren’t getting outside! This would be a far more relevant question to ask yourself if this is you.
As an aside about being indoors... UVB’s don’t shine through glass. But the UVA’s do. So… you can get a burn, but not the vitamin D. Lame. No tanning through the windows. Speaking of which, UVB permeable/UVA blocking glass for windows would be an amazing business idea! Anyone know anything about this?
Brainstorming quickly I came up with these ideas:
Now, I’d like to hear from you!
Discussion questions: Were you also wondering about sunscreen and vitamin D? Did you know this information before? What new learning did you add to your understanding? Do you take a vitamin D supplement?
Leave a comment below, you never know when sharing your thoughts might help someone else! Or just be a gem and let me know if you liked this post? lol. The topics I'm writing about are all kind of shots in the dark until I hear what you'd like to read about.
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