Sunscreen's vitamin D effect is not worth worrying about.

Probably not enough to matter.

Yes, sunscreen blocks UVB rays, which your skin uses to make vitamin D. An SPF 15 blocks about 93% of UVB. But here’s the thing—most people don’t apply sunscreen perfectly, miss spots, and get small amounts of incidental sun exposure through the day anyway. That leftover 7% of UVB is often enough to maintain decent levels.

The real concern is the other way around: not wearing sunscreen because of vitamin D fears is how you get sunburn, premature aging, and skin cancer. Those are much more concrete problems than a theoretical vitamin D deficiency. Most vitamin D deficiency is driven by latitude, time indoors, and diet—not sunscreen habits.

If you’re genuinely worried, get your levels checked. If they’re low, take a supplement. It’s cheaper than a melanoma.

Worry about sunburn, not vitamin D.