Does daily sunscreen use cause vitamin D deficiency?
Yes, if you apply high-SPF sunscreen every single day on days when the UV index is 3 or higher, your vitamin D levels will likely drop. The strongest evidence comes from a year-long randomized controlled trial (the Sun-D Trial) in Australia, where participants who used SPF 50+ sunscreen daily saw their vitamin D levels fall by an average of 5.2 nmol/L more than those who used sunscreen only when they felt like it [1]. By the end of the study, 45.7% of daily sunscreen users were vitamin D deficient (below 50 nmol/L), compared to 36.9% in the discretionary-use group [1]. That's a meaningful difference—about 1 in 3 people who use sunscreen daily may become deficient.
But this effect is not universal. A separate analysis of UK Biobank data found that people who reported using sunscreen actually had higher vitamin D levels than those who never used it, and the lowest levels were seen in people who avoided the sun entirely [2]. This seems contradictory, but it makes sense: people who use sunscreen are often the same people who spend more time outdoors, so they still get enough UV exposure to make vitamin D. The key is that daily, thorough application can block enough UVB to reduce vitamin D synthesis, while typical 'beach day' use still lets plenty of UV through.
Does typical sunscreen use (not daily) still cause deficiency?
For most people, no—typical sunscreen use does not cause vitamin D deficiency. Studies in children and adults in sunny countries like Greece show that those who used sunscreen on the beach or during summer actually had higher vitamin D levels than those who didn't [3]. In a study of 376 Greek children, kids who used sunscreen at the beach had significantly higher vitamin D levels (p=0.001) [3]. This is because sunscreen is rarely applied perfectly—people miss spots, use too little, or reapply too late—so enough UVB still reaches the skin to trigger vitamin D production.
However, there is a seasonal catch. A study in Greek adults found that using sunscreen during summer was linked to lower vitamin D levels measured the following winter [7]. And a study in Iranian adolescent girls found that those who used sunscreen had significantly lower vitamin D levels than those who didn't (p=0.004) [4]. So the effect depends on how much sun you get overall: if you live in a high-latitude area with long winters, or if you combine sunscreen with other sun-avoidance behaviors (like staying indoors), your vitamin D may suffer. The US National Health and Nutrition Examination Survey (NHANES) data found that wearing long-sleeved shirts frequently was linked to a 3.3 times higher odds of vitamin D deficiency, but sunscreen use alone was not [6].
Who should worry about vitamin D when using sunscreen?
The people most at risk are those who combine daily sunscreen use with other factors that limit vitamin D production. A study in Greek adults found that higher body mass index (BMI) and sunscreen use together were strongly linked to low vitamin D in winter [7]. Adolescents and girls are also more vulnerable: a study of children in Turkey found that girls and older children had lower vitamin D levels, and sunscreen use was more common in those with deficiency [5]. In the Sun-D Trial, the effect of daily sunscreen was consistent across age, sex, and skin type, meaning no subgroup was completely protected [1].
If you are a daily sunscreen user—especially if you have darker skin, live far from the equator, are overweight, or spend most of your time indoors—you should consider having your vitamin D levels checked. The Sun-D Trial authors explicitly recommend that regular sunscreen users may need vitamin D supplementation [1]. The good news: taking a vitamin D supplement (even just 20 μg per day over a month) was shown to eliminate the increased risk of deficiency from sun protection behaviors in the NHANES study [6].
About These Sources
This answer is built on 7 peer-reviewed studies — published from 2021 to 2025, 2 from 2024 or later, 3 in Q1 journals — selected as the most relevant from 8 studies that passed quality screening, drawn from 51 papers retrieved from a database of over 500 million.
Sources used in this answer
Effect of daily sunscreen application on vitamin D: findings from the open-label randomized controlled Sun-D Trial.
In a year-long randomized controlled trial (Sun-D Trial), daily use of SPF 50+ sunscreen led to 5.2 nmol/L lower vitamin D levels and a 33% higher prevalence of deficiency compared to discretionary use [1].
Comment on ‘Effect of daily sunscreen application on vitamin D: findings from the open-label randomized controlled Sun-D Trial’
Analysis of UK Biobank data found that sunscreen users had higher vitamin D levels than non-users, while complete sun avoiders had the lowest levels, suggesting real-world use still allows vitamin D synthesis [2].
Vitamin D Status in Children in Greece and Its Relationship with Sunscreen Application
In 376 Greek children, those who used sunscreen at the beach had significantly higher vitamin D levels (p=0.001), indicating that typical summer use does not cause deficiency [3].
Evaluation of the knowledge regarding vitamin D, and sunscreen use of female adolescents in Iran
Among 940 Iranian adolescent girls, those who used sunscreen had significantly lower serum vitamin D levels (p=0.004), but knowledge about vitamin D was poor [4].
Vitamin D Levels in Children During Winter and the Relationship Between Sunscreen and Sun Protection Behaviors
In 376 Turkish children, sunscreen use was associated with lower vitamin D levels in winter; girls and adolescents were more likely to be deficient [5].
Effects of sun protection on serum vitamin D deficiency
Using US NHANES data, wearing long-sleeved shirts frequently was linked to 3.3 times higher odds of vitamin D deficiency, but sunscreen use alone was not; vitamin D supplementation eliminated the risk [6].
Increased Body Mass Index (BMI) and Sunscreen Use Are Associated with Inadequate Vitamin D Status in Greek Adults in Winter : BMI, Sunscreen Use and Vitamin D Status in Greek Adults.
In 36 Greek adults, sunscreen use during summer was negatively associated with winter vitamin D levels; higher BMI also predicted lower levels [8].