Any links to the result that suncreen usage doesn't affect Vitamin D production? (Intake seems the wrong word)?
It's the first time I heard that.
It's the first time I heard that.
If you apply and then spend a lot of time in the sun, your vitamin production will be decreased, but not entirely. People who routinely apply sunblock spend more time in the sun, so they will end-up producing more than those who spend no time in the sun at all.
It's the cost of weighing burns against vitamin D production. The skin cancer worry (legitimate) due to sun damage vs. decreased vitamin D production is probably a good bet to make.
Sunscreen is for one thing - so you can spend more time in the sun. If you'd burn after 15 minutes, then SPF 20 means you can spend about 5 hours with sunscreen. No SPF will entirely eliminate the sun - that'd be SPF infinity, right? SPF is a ratio.
Leaving sun screen aside (as that seems to only prolong the time you need to stay in the sun for an effect, good or negative). I suspect the number of minutes you should stay in the sun per day is > 0. But how high is it?