The Effect of Sunscreens On Your Vitamin D Level
Sunscreens are an important tool in the prevention of sunburns. Sunburns should be avoided, at all costs, and especially for children. Sunburns seem to be the highest predictor of future non-melanoma skin cancers, along with total sun exposure.
Sunscreens with an SPF factor of 30 will block 99% of vitamin D production. The NIH states in their Vitamin D Document For Professionals that SPF 8 will block most vitamin D production, and some experts agree that this will block 90% of your vitamin D production. It is the UVB rays that stimulate Vitamin D production and even a glass window blocks the UVB rays. Sitting indoors and getting sunlight through a glass window, will not help you build your vitamin D levels.
If you take adequate vitamin D3 and have an adequate vitamin D level, you may avoid the sun and use sunscreen whenever you are in the sun. There is likely a benefit to sun exposure that goes beyond Vitamin D however, so I still think it a good idea to get up to 15 minutes a day (if that exposure won’t burn you or make your skin red) a few times a week. Somehow, growing up in Africa, it just seems wrong to avoid the sun. I suspect my Native American friends would agree. Most cultures from before the industrial revolution included significant time outdoors and in the sun. In the locations away from the equator, there is an 80-100% reduction in vitamin D synthesis during the winter months, even in places like Florida.
Get outdoors, and if you’ll be out in full sun for long enough to burn or get red, then use sunscreen after 5-15 minutes, with an SPF of at least 8 to 30.