Originally Posted by
OBoile
Overexposure is certainly bad. The question is: what constitutes overexposure? Putting on sunscreen when you're going to be outside for 20 minutes seems pretty extreme, particularly if you aren't very fair skinned.
A comparison of sunscreen to a helmet isn't very apt. A helmet has no real downside from a health perspective, while getting insufficient sunlight seems to pose a real risk to one's physical and mental health. I'll trade a slightly increased risk of skin cancer, the vast majority of which is not particularly dangerous, for:
Lower risk of hypertension
Lower risk of diabetes
Lower risk of depression
Lower risk of prostate, breast, colorectal, and pancreatic cancers
Lower risk of blood clots
Reduced inflammation
and a reduced overall mortality rate.
I agree with you. Yes, vitamin D deficiency is a significant health issue; perhaps the most common nutritional deficiency worldwide. So, getting sunlight is important but, once adequate sunlight is obtained, getting more produces no meaningful incremental benefit. So, then the question isn't what constitutes overexposure. The issue is how much sunlight is needed. For most people that's only 10-15 minutes a day on a small portion of skin like one arm.
All that considered, applying sunscreen should be considered for any activity that's substantial in length.