Reviewed November 11, 2026

Does Sunscreen Block Vitamin D? What the Trials Actually Found

Sunscreen blocks UVB, and UVB is what the body uses to make vitamin D, so the theory says daily sunscreen should cause deficiency. In real life it does not, and the evidence is unusually clear. A 2019 review in the British Journal of Dermatology looked at 4 lab experiments, 3 field trials, and 69 observational studies, and concluded there is little evidence that sunscreen decreases vitamin D concentration when used in real-life settings. In a Melbourne trial, 113 adults used broad-spectrum SPF 17 or a dummy cream every day over a summer, and vitamin D rose by almost the same amount in both groups. On a week-long sun holiday in Tenerife, people who used SPF 15 thickly enough to prevent sunburn still saw their vitamin D rise significantly. The reason is mundane: nobody applies sunscreen perfectly, and the skin that is missed, the scalp, the gaps between fingers, the edges of the face, receives enough UVB. The fix for low vitamin D is a supplement, not less sunscreen.

The theory, and why it sounds convincing

The theory is simple and it is correct as far as it goes. The body produces vitamin D when skin is exposed to UVB radiation in the 270 to 300 nanometer range, with peak synthesis around 295 to 297 nanometers. Sunscreen blocks UVB. The action spectra of erythema, sunburn, and vitamin D formation overlap significantly in the UVB region, so a sunscreen that inhibits sunburn should theoretically also inhibit vitamin D production. In lab experiments with artificial UV lamps, that is exactly what happens: sunscreen use considerably abrogated vitamin D production. The lab result is real, and it is the reason the claim that sunscreen causes deficiency keeps circulating. The problem is that the lab is not real life, and real life has a way of undoing the theory.

What the trials actually found

A 2019 review led by researchers at QIMR Berghofer in Brisbane, published in the British Journal of Dermatology, looked at 4 lab experiments, 3 field trials, 2 of them randomized, and 69 observational studies. The lab experiments showed sunscreen substantially reducing vitamin D production. The randomized field trials showed no effect from daily sunscreen use, though the sunscreens in those trials had moderate protection, around SPF 16, and no trials have yet tested the very high SPF products most people now buy. Of the 69 observational studies, 25 percent concluded sunscreen use was associated with higher vitamin D concentrations, and 10 percent with lower. The authors concluded there is little evidence that sunscreen decreases 25(OH)D concentration when used in real-life settings, and that vitamin D concerns should not override skin cancer prevention advice. The best single trial has a Melbourne accent: 113 Australians aged 40 and over were randomly given either a broad-spectrum SPF 17 sunscreen or a dummy cream to use every day over summer. By the end of summer, vitamin D levels had risen by almost the same amount in both groups, and no one, including participants aged 70 and over, ended up with vitamin D outside the normal range.

Why real life undoes the theory

The explanation is mundane. Most people do not apply sunscreen uniformly enough to block UVB synthesis entirely. Areas that are typically missed or under-applied, the scalp, gaps between fingers, the backs of the hands, the edges of the face, receive enough UVB for adequate vitamin D production even with SPF applied everywhere else. Even well-applied sunscreen at the correct amount, 2 milligrams per square centimeter, does not block 100 percent of UVB: SPF 50 blocks approximately 98 percent, so 2 percent still reaches the skin, and for short midday exposures that residual UVB can be sufficient. And a 2019 study of people on a week-long sun holiday in Tenerife, who used SPF 15 thickly enough to prevent sunburn, found their vitamin D levels still rose significantly. The authors concluded that sunscreen can prevent sunburn yet allow vitamin D synthesis. The lab studies also use artificial UV with a different spectrum from real sunlight, which is part of why the lab result does not transfer.

What to do instead of skipping sunscreen

When the UV index is 3 or above, most people maintain adequate vitamin D levels just by spending a few minutes outdoors on most days of the week. The exposure required is considerably less than most people assume: about 25 percent of the body exposed to half the minimal erythemal dose, two to three times per week, is sufficient for most people, and midday is the most efficient time. In Germany, Switzerland, Austria, and the UK, UVB intensity from October to March is often insufficient for meaningful synthesis at any time of day, regardless of how long you spend outdoors or how little sunscreen you apply. UVB does not pass through window glass, so indoor sun exposure does not contribute to vitamin D at all. The honest answer is that vitamin D supplementation is a safer and more reliable approach than reducing sun protection. If your levels are low, get a blood test and take a supplement. Do not trade skin cancer risk for a vitamin you can swallow.

Frequently asked questions

Does sunscreen cause vitamin D deficiency?

In real life, no, not in a way that should worry most people. A 2019 review in the British Journal of Dermatology examined lab experiments, field trials, and 69 observational studies, and concluded there is little evidence that sunscreen decreases vitamin D concentration when used in real-life settings. Cancer Council Australia puts it plainly: sensible sun protection does not put people at risk of vitamin D deficiency. If your levels are low, a supplement is the fix, not less sunscreen.

Why do lab studies show sunscreen blocking vitamin D?

Because lab studies use artificial UV lamps and perfect application, and under those conditions sunscreen does cut vitamin D production right back. Real sunlight has a different spectrum from the lamps, and real people apply sunscreen thinly and unevenly, miss areas, and reapply less often than the instructions say. Even well-applied sunscreen at the tested amount does not block 100 percent of UVB: SPF 50 blocks about 98 percent, so 2 percent still reaches the skin, and for short midday exposures that residual UVB can be enough.

How much sun do I need for vitamin D?

When the UV index is 3 or above, most people maintain adequate vitamin D levels just by spending a few minutes outdoors on most days of the week. Research suggests that exposing about 25 percent of the body to half the minimal erythemal dose, the minimum UV needed to cause visible redness, two to three times per week is sufficient. Midday is the most efficient time, because UVB intensity is highest then. In northern Europe, UVB intensity from October to March is often too low for meaningful synthesis regardless of SPF use.

Should I skip sunscreen to get more vitamin D?

No. Overexposure to UV is never recommended, even if you have a vitamin D deficiency. The vitamin D you gain from unprotected sun exposure comes with the UV damage that drives skin cancer risk, and a supplement gives you the vitamin D without the damage. If you are worried about your levels, get a blood test and take a supplement. Do not trade skin cancer risk for a vitamin you can swallow.