Exposure to UVB radiation is responsible for over 90% of vitamin D production, but it is also the primary cause of sunburn and skin cancer. Therefore, the daily application of sunscreen is recommended to reduce the harmful effects of the sun. However, some fear that their widespread use, especially those with high sun protection factors, may block UVB rays and prevent vitamin D synthesis, thereby causing a deficiency. Can sunscreen indeed compromise this reaction?
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Does sunscreen prevent the synthesis of Vitamin D?
Summary
Published April 20, 2023,
updated on October 4, 2024,
by
Stéphanie, PhD, Doctorate in Life and Health Sciences
—
11 min read
Why do we need Vitamin D?
Vitamin D is essential for skeletal integrity and has been associated with numerous other health benefits. Indeed, it enhances the intestinal absorption capacity of calcium and phosphorus, which promotes the mineralization of bones, teeth, and joints, as well as muscle tone. Over 90% of vitamin D comes from sun exposure, which can then lead to seasonal variations in temperate climates. Therefore, it is crucial to get enough sun exposure to ensure optimal levels of vitamin D.
In brief, UVB radiation converts 7-dehydrocholesterol (also known as pro-vitamin D) in the epidermis into pre-vitamin D3. The action spectrum of this reaction indicates that it occurs in the UVB waveband (290 - 315 nm) with maximum efficiency at 295 nm. Formed from pre-vitamin D3 through progressive thermal isomerization, vitamin D3 then travels to the liver where it is hydrolyzed into 25-hydroxyvitamin D [25(OH)D], the circulating form. Subsequently, it is transported to the kidneys for a second hydroxylation to become 1,25(OH)2D (calcitriol), which is the active form of vitamin D.
In order to meet the daily vitamin D requirements (estimated at 1,000 IU per day), several studies and reports suggest that spending about 15 to 30 minutes per day is sufficient to synthesize vitamin D.
Does sunscreen prevent meeting daily vitamin D requirements?
In recent years, people have expressed concern that the widespread use of sunscreen, particularly those with a high sun protection factor, could increase the risk of vitamin D deficiency.
What do we know at this point?
The UV rays from the sun are responsible for sunburns and are also recognized as carcinogenic. Indeed, they are the main risk factor for skin cancers, particularly in populations with fair skin for whom sunburns are a risk factor. Numerous public health efforts have been made to raise awareness about the inherent dangers of sunbathing.
The use of sunscreens is one approach, and randomized trials have shown that they inhibit the development of skin cancers. The role of sunscreens in preventing melanoma has also been supported by large population-based studies.
However, the use of sunscreens appears to have an impact on vitamin D status. The action spectra of erythema and cutaneous formation of vitamin D overlap significantly in the UVB region. Thus, sunscreens that inhibit erythema should theoretically also inhibit the production of vitamin D.
What do the studies say?
Studies on the inhibitory effects of sunscreens on vitamin D synthesis have yielded contradictory results. Some authors have found a significant inhibition of its production, while others report no influence of sunscreens on vitamin D.
Sunscreen protects the skin from the harmful rays of the sun by filtering UV rays. These consist of different types of UV rays, including UVA and UVB. UVB rays are both responsible for the synthesis of vitamin D, but also for sunburn. Since UVB rays are filtered by sunscreen, it is reasonable to think that the body may not synthesize enough vitamin D.
A recent study presents conflicting data on the matter. The four experimental studies included in the review showed that the use of sunscreen mitigated any increase in the concentration of circulating vitamin D3 or 25(OH)D, which occurs following exposure to artificially generated UV radiation. Of the 69 observational studies included in the review, 25% concluded that sunscreen use was associated with higher concentrations of 25(OH)D, while 10% concluded that sunscreen use was associated with lower concentrations of 25(OH)D. The authors note that the conclusions of these observational studies are limited by their heterogeneity, study design, and sub-optimal reporting.
This review also included two randomized controlled trials conducted in Australia. In one of these studies, participants were given either a sunscreen or a placebo, and were instructed to apply it daily. In the second study, one group was asked to apply sunscreen daily to their face, neck, arms, and hands, while the other group was advised to apply sunscreen at their discretion. Both studies compared the concentration of 25(OH)D between the two groups and found no statistical difference. The authors conclude that while there is a theoretical risk that sunscreen could decrease vitamin D levels, current data does not demonstrate a correlation in real life.
This conclusion is supported by a more recent study, which showed that during a one-week vacation in Tenerife (Spain), individuals applying an SPF15 sunscreen at the recommended thickness of 2mg/cm2 showed no signs of sunburn and also exhibited a significant increase in serum levels of 25(OH)D. Thus, despite the optimal use of a low sun protection factor sunscreen, these individuals had sufficient vitamin D production.
| References | Sample Size | Exposed Surface | Frequency of Exposure | UVB Dosage | Type of Sunscreen | Results |
|---|---|---|---|---|---|---|
| HOLICK M. F. & others (1987) | In vitro study on human skin samples | 1 time | 30mJ/cm2 | 5% of para-aminobenzoic acid (PABA) | Production of pre-vitamin D3 completely blocked by sunscreen | |
| MATSUOKA L. Y. & al (1987) | 8 subjects with white skin | 100% | 1 time | 1 UNIT | SPF 8 containing PABA | Unchanged concentration of vitamin D3 in the group that applied the sunscreen compared to the placebo group |
| HOLLIS B. W. & al (1990) | 27 subjects (phototype III) | 100% | 1 time | 27mJ/cm2 | SPF 15 | Complete blockage of the synthesis of Vitamin D3 |
| THOMPSON S. C. & others (1995) | 113 subjects | Face, neck, forearms, back of the hands | Once a day for 7 months | SPF 17 | No influence on the levels of 25(OH)D | |
| RODRIGUEZ J. & et al. (1998) | 24 subjects | Once a day for 24 months (only during the spring and summer months) | SPF 15 | No influence on the levels of 25(OH)D | ||
| FAURCHOU & al (2012) | 37 volunteers (phototype I to III) | Upper part of the body | 4 times every 2 - 3 days | SPF 8 (0mg/cm2, 0.5mg/cm2, 1mg/cm2, 1.5mg/cm2, or 2mg/cm2) | Correlation between the amount of sunscreen applied and the concentration of 25(OH)D | |
| VAN DER POLS J. C. & al (2012) | 1,113 volunteers | Face, neck, forearms, back of the hands | Once a day for four and a half years | SPF 16 | No impact on circulating levels of 25(OH)D | |
| NIKKELS A. F. & et al. (2017) | 72 volunteers | 4 groups: 9%, 23%, 50%, and 96% | 1 time | 0.8 DEM | SPF 50 (2mg/cm2) | No impact on circulating levels of Vitamin D for short-term use of sunscreen. |
| PHILIPSEN P. A. & et al. (2019) | 20 volunteers | 3 times a day for a week | SPF 15 (2mg/cm2) | Significant increase in serum levels of 25(OH)D |
On the other hand, real-life situations demonstrate that vitamin D levels are not affected by the use of sunscreen. These results could be explained by several facts:
Sunscreens can encourage individuals to expose themselves more frequently and for longer periods to the sun;
the amount of sunscreen spontaneously applied to the skin is usually less than the recommended quantities;
The complete blocking of UVB rays by sunscreens is likely never achieved.
There are safe ways to obtain Vitamin D without relying on the sun. One of the most common recommendations is oral supplementation of Vitamin D through dietary supplements. Milk is another source: a 250 mL glass of milk contains approximately 100 IU of Vitamin D. Another dietary source is fatty fish such as salmon, eel, or mackerel.
In conclusion, studies show that the application of a generous amount of any sunscreen does not alone disrupt the body's synthesis of vitamin D. It is thus possible to stimulate its production by applying a high SPF sunscreen. However, we recommend considering other sources of vitamin D, such as dietary supplements or food.
Sunscreens can be used to prevent sunburns, while still allowing for the synthesis of Vitamin D.
Sources
HOLICK M. F. & al. Sunscreens suppress cutaneous vitamin D3 synthesis. Journal of Clinical Endocrinology and Metabolism (1987).
HOLLIS B. W. & al. Use of topical sunscreen for the evaluation of regional synthesis of vitamin D3. Journal of the American Academy of Dermatology (1990).
THOMPSON S. C. & al. The effect of regular sunscreen use on vitamin D levels in an Australian population. Results of a randomized controlled trial. Archives of Dermatology (1995).
RODRIGUEZ J. & al. Clinically prescribed sunscreen (sun protection factor 15) does not decrease serum vitamin D concentration sufficiently either to induce changes in parathyroid function or in metabolic markers. British Journal of Dermatology (1998).
FALLON J. C. & al. Photoprotective behaviour and sunscreen use: impact on vitamin D levels in cutaneous lupus erythematosus. Photodermatology, Photoimmunology & Photomedicine (2008).
VAN DER POLS J. C. & al. Sun protection and vitamin D status in an Australian subtropical community. Preventive Medicine (2012).
WULF H. C. & al. The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial. British Journal of Dermatology (2012).
BENS G. Sunscreens. Advances in Experimental Medicine and Biology (2014).
NIKKELS A. F. & al. Sunscreens block cutaneous vitamin D production with only a minimal effect on circulating 25-hydroxyvitamin D. Archives of Osteoporosis (2017).
SERRANO M.-A. & al. Contribution of sun exposure to the vitamin D dose received by various groups of the Spanish population. Science of The Total Environment (2018).
PHILIPSEN P. A. & al. Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. British Journal of Dermatology (2019).
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