“Sunscreen causes vitamin D deficiency.”
One year-long Australian randomized trial found lower vitamin D with routine SPF50+ use than discretionary use. The result is credible for that regimen, but does not establish that every sunscreen user becomes deficient.
Routine high-SPF sunscreen can modestly lower measured vitamin D in some people, but it does not automatically cause clinically meaningful deficiency. In an Australian trial, routine SPF50+ use produced levels about 5 nmol/L lower than discretionary use, using a threshold that is not a universal definition of deficiency.
Vitamin D thresholds differ: the trial used below 50 nmol/L; NIH describes below 30 nmol/L as deficiency risk and 30–49 nmol/L as potential inadequacy.
Safety note: Do not deliberately increase unprotected UV exposure to correct vitamin D. UV radiation causes skin cancer.
Talk to a healthcare professional if: Discuss vitamin D intake and whether testing is indicated if you have risk factors or a diagnosed low level. Routine testing is not recommended for everyone.
Keep protecting your skin. Review vitamin D intake separately if you use high-SPF sunscreen routinely or have other risk factors.
Consider food sources and, when appropriate, clinician-guided supplementation rather than extra UV exposure.
Similar claims on Sunscreen & sun exposure
Don't fall for the sunscreen scare. Protecting your skin is one of the clearest, best-evidenced health habits there is. If you use high-SPF sunscreen very consistently, vitamin D is easy to address through food, supplementation, or testing, not by cutting back on sun protection.