Transcript
What do human foreskins, vitamin D, and sunscreen have in common? Great question! I'm glad you thought to ask. We'll explain with a scientific study in a quick demo. Welcome back to what the science, sunscreen edition. There are three types of UV light, A, B, and C. A is closest to the visible light spectrum and has the longest wavelengths. This is what black lights produce and makes up around 95% of all solar UV hitting the Earth. UVC is like a solar fart, short but deadly, and thankfully doesn't make it through the atmosphere. If only Steve were in orbit. UVB, the misunderstood middle child of Daddy Helios. It's what causes most of sunburns, but also triggers vitamin D production. And the amount that makes it through the atmosphere varies based on time of day, time of year, latitude, and altitude, based on the same principle that makes wildfire smoke turn the air orange. Which brings us to foreskins. I don't even know what they did with my foreskin. It's tough to actually measure vitamin D production in human skin, because apparently most humans like to keep their skin attached to their bodies. I tell them it's for science, but still they're like, no. So, researchers got a hold of baby fourskins, donated at time of circumcision, and they exposed them to varying amounts of Boston sunlight all throughout the year. From December to February, sunlight exposure produced no vitamin D production in the skin, because there wasn't enough UVB getting through the atmosphere. So what about sunscreen? It's all about dose. It's been shown that people who are photosensitive and so use large amounts of high SPF sunscreen, protective clothing, and stay in the shade a lot, they're more likely to be vitamin D deficient. No surprise. If this is sunlight, vitamin D production starts to start with, around here, but it caps out around here. You want to get around this amount. Any more than that, and suddenly, your body starts to burn. So absolutely use sunscreen when going out in some heavy sun. But if your only outdoor time is that 10 minute lunch break at work, then don't overdo...
Additional notes
Replying to @iam4unotagainstu have you ever been burned while wearing sunscreen? You probably got plenty of vitamin d while doing so. If there’s ever even a remotr chance of burning, the evidence supports wearing sunscreen trumping any worries of limiting vitamin D production. You’ll get enough! #sunscreen #science #sunburn #vitamind #edutok #skincare