If I use SPF50+ sunscreen every day do I need to take vitamin D?

What does wearing SPF50+ sunscreen every day do to your vitamin D levels? Our study, recently published in the British Journal of Dermatology, provides some answers.

We found using SPF50+ every day, on all days when the ultraviolet index is forecast to reach three or more, can increase the risk of being vitamin D deficient.

The benefits of sunscreen are well known, so our findings do not mean we should abandon SPF50+.

Rather, it means people who use SPF50+ every day might need to start taking vitamin D supplements.

Why did we run our trial?

Sunscreen is designed to reduce the amount of ultraviolet (UV) radiation reaching the skin’s cells. However, exposing the skin to UV rays from the sun produces vitamin D, so it is reasonable to think that sunscreen would block vitamin D production.

Previous studies found using low SPF sunscreen daily did not cause vitamin D deficiency.

However, nobody had assessed the effect of routinely using high SPF sunscreens in everyday life, so in the Sun-D Trial we tested the effect of using SPF50+ every day.

What did we do?

We recruited 639 adults living in one of the four eastern states of Australia (and the Australian Capital Territory) who were not using sunscreen as part of their daily routine.

We put them randomly into one of two groups. We gave the “sunscreen” group SPF50+ sunscreen and asked them to apply it every day (to all areas of the skin not covered by clothes) when the UV index was forecast to reach three or more for a year.

We asked the “control” group to continue with their usual sun protection.

We measured vitamin D levels at the beginning (late winter/early spring), middle (late summer), and end (late winter) of the study in both groups.

What did we find?

The average vitamin D level increased in both groups from late winter to late summer. However, the increase was significantly lower in the sunscreen group than in the control group.

At the end of the study, vitamin D deficiency was more common in the sunscreen group than in the control group (46% versus 37%).

This is the first study worldwide to test the effect of daily SPF50+ sunscreen use in people as they go about their everyday lives.

What does this mean?

1. Keep using sunscreen

Using sunscreen daily reduces the risk of skin cancer and sunspots. Therefore it is very important Australians continue to use sunscreen every day when the UV index is forecast to reach three or more as part of their daily routine.

For people with deeply pigmented skin, daily sunscreen is not needed because the risk of skin cancers caused by the sun is very low. It is still important, though, to protect the skin if outdoors when the UV index is high.

Using sunscreen should be as routine as brushing your teeth. Continue to use sunscreen with a high SPF (ideally 50+, but 30+ is also OK if you can’t find a 50+ that you like). Don’t rely on sunscreen in makeup, which doesn’t offer enough protection.

If you spend time outdoors for recreation or work when the UV index is three or more, you should cover as much skin as you can with clothing, wear a hat and sunglasses, stay in the shade if you can, and reapply sunscreen every two hours.

2. Consider taking vitamin D

People who use sunscreen daily should consider taking a vitamin D supplement. These are relatively cheap (as little as 5c per day), safe (if used as directed), and effective for preventing vitamin D deficiency.

It is more important to take supplements over winter, as that is when vitamin D deficiency becomes more common.

Vitamin D deficiency is also more common in southern states. In Australia’s National Health Measures Survey, 26% of people in Tasmania were vitamin D deficient (46% in winter) compared to 12% in Queensland (16% in winter).

Is regular sunscreen use the only cause of vitamin D deficiency?

A total of 30% of participants were vitamin D deficient at the start of the study, even though they were not regular sunscreen users. And 37% of the control group (who did not use sunscreen every day) were vitamin D deficient at the end of the study.

This shows regular sunscreen use is not the only reason for being vitamin D deficient. People who rarely go outdoors between 8am and 4pm, or who always cover most of their skin with clothing when they are outside, are at increased risk of being vitamin D deficient.

Should I have my vitamin D levels tested first?

The Australian government only funds vitamin D tests in people where there is a specific clinical reason for testing. Also, it is not always easy for everybody to see a doctor, and not everybody can see a doctor for free.

If you think you might be at risk of being vitamin D deficient because you are careful to protect your skin from the sun – or have other reasons you don’t expose your skin to the sun – you can start taking vitamin D supplements without having your vitamin D tested first. Perhaps discuss this with your doctor when you get a chance.

This is safe, so long as you follow the instructions on the label.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Rachel Neale, QIMR Berghofer Medical Research Institute; Briony Duarte Romero, QIMR Berghofer Medical Research Institute, and Vu Tran, QIMR Berghofer Medical Research Institute

Rachel Neale received funding from the National Health and Medical Research Council for the Sun-D Trial and other studies related to skin cancer and vitamin D.

Vu Tran has received PhD sholarships from the University of Queensland and the QIMR Berghofer.

Briony Duarte Romero does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.