Vitamin D, ingredients, and allergies: what you need to know about sunscreens

Summer in Eastbourne, Wellington.
photograph: RNZ / Rebecca Parsons King

“If I could offer one tip for the future, it would be sunscreen.

“While the long-term benefits of sunscreen have been proven by scientists, the rest of my advice has no more reliable basis than my own tortuous experience.”

So says Baz Luhrmann's 1997 spoken word song “Everybody's Free (To Wear Sunscreen),” based on an essay by Mary Schmich.

What was commonplace health advice at the time has become controversial in some circles thanks to social media influencers. activist groupand marketing person.

The questions raised are not new, although many relate to vitamin D deficiency, sunscreen ingredients, and allergies. But every summer, misinformation about sunscreen seems to increase and spread. It's a bit like cancer.

This is of particular concern in Aotearoa, New Zealand and Australia, where the incidence of melanoma, the deadliest of the common skin cancers, is particularly high. the highest in the world. Approximately 350 New Zealanders die from melanoma each year.

But mistrust is not the only problem. Dermatologists say most people who use sunscreen simply don't apply it enough.

skin cancer

The three main types of skin cancer are squamous cell carcinoma, basal cell carcinoma, and melanoma.

Most skin cancers are caused by overexposure to ultraviolet (UV) light. One of the most preventable cancers.

According to NIWA, UV levels in New Zealand in the summer are higher than in corresponding latitudes in the Northern Hemisphere.

The Australasian Society of Dermatologists recommends minimizing exposure to excessive UV radiation from the sun, wearing protective clothing such as a wide-brimmed hat and sunglasses, and wearing a broad-spectrum, water-containing sunscreen with an SPF of 50 or higher. We recommend that you reduce the risk by using resistant.

Babies under 6 months should avoid direct sunlight.

Other risk factors In the case of skin cancer, these include a family history of skin cancer and a skin type that burns easily.

Sunscreen

Let's get back to basics. Sunscreens are topical agents that can be applied to the skin to protect the skin from ultraviolet radiation, which contributes to skin aging and is a leading cause of skin cancer.

But you shouldn't rely solely on sunscreen to protect yourself from the sun.

“First and foremost, people should wear appropriate clothing and headwear wherever possible, and use sunscreen if they can't cover their skin,” says consultant dermatologist and New Zealand Dermatology Society president-elect Dr Scott Barker. told RNZ.

Sunscreens are often classified as “physical” or “chemical” depending on their ingredients and how they work.both provide protection Mainly by absorbing ultraviolet light.

SPF

The sun protection factor (SPF) rating tells you how well a sunscreen protects your skin from sunburn. (No sunscreen can block 100% of the sun's rays.)

On a less technical note, SPF is the ratio of the amount of UV radiation required to cause a sunburn on skin treated with sunscreen to the amount of UV radiation required on untreated skin.

It is important to clarify that it is related to the amount of sun exposure, not the duration of sun exposure. It has been found that at noon, we are exposed to the same amount of solar energy for less time than in the early morning or late at night. The strength of sunlight also depends on your geographic location.

The higher the SPF number, the more protection you can expect.

“It's true that a higher broad-spectrum SPF provides longer protection from UV damage, which is why SPF 50 is better than SPF 30,” says Barker.

While sunburn is most often the result of exposure to ultraviolet B (UVB) rays, ultraviolet A (UVA) rays are known to cause skin damage. “Broad-spectrum” sunscreens protect against both.

vitamin D

For most people, sunlight exposure is the main source of vitamin D. Often referred to as the sunshine vitamin, it plays an important role in bone health.It also affects Inflammation, autoimmune disease risk, heart health, and cognitive function.

A common concern is whether sunscreens inhibit vitamin D absorption.

“Experimental laboratory studies show that sunscreens do reduce the production of vitamin D caused by artificial UV radiation,” Professor Barker said.

“However, real-world trials using moderate SPFs have not shown this, and there are also no real-world observational studies using sunscreens with higher SPFs.”

The authors concluded: “While there may be a theoretical risk, concerns about vitamin D should not negate advice to prevent skin cancer, as the risk is very low with daily use.”

material

US Food and Drug Administration The data has been published This suggests that chemical sunscreen ingredients can penetrate the bloodstream.

Animal studies and in vitro studies have also shown that some sunscreens, such as homosalate, oxybenzone, and octinoxate, affect endocrine activity.

Research into these findings is ongoing. The FDA said the results do not mean the ingredient is unsafe and people should continue using sunscreen.

For example, questions have been raised about the safety of carcinogenic zinc oxide and titanium dioxide nanoparticles.

“Evidence suggests that some chemical sunscreen ingredients and some nanoparticles of zinc and titanium can be absorbed systemically, but there is not enough evidence that they are harmful. '' Barker said.

Skin cancer, on the other hand, is a known risk.

“Regulators are monitoring this data and generally believe the benefits outweigh the risks.”

allergy

Reactions to sunscreen are rare.

Side effects of sunscreen include a stinging sensation after application, skin irritation, and a rash (usually contact dermatitis). dermnet new zealand.

Zinc oxide and titanium dioxide may be less likely to cause irritation than chemical sunscreens.these are generally recommended For young children.

“Some people may have an allergic reaction to some chemical filters in sunscreens,” Baker said. “If you suspect this, a dermatologist can perform a test. In that case, you can use a sunscreen that avoids chemicals that cause allergies.”

choose one

Ideally, choose a water-resistant, broad-spectrum sunscreen with at least SPF 30. But perhaps more importantly, find a sunscreen that you use consistently and keep reapplying.

For example, your face may need different products than other areas. One for the beach and one for sports.

The most important thing is to apply it enough, Barker says.

“Most people don't apply enough. Dermatologists do, most people who have had skin cancer many times do, but most people don't apply enough. I don't apply it until I start getting it.The most important thing is to find a sunscreen that you like, so you can apply it enough. ”

What about aerosol sunscreens?Avoid them, Cancer Council Australia It is recommended. Research has shown that it is difficult to obtain sufficient levels of UV protection even with spray sunscreens. Use creams or lotions instead.