Jessica Alba’s company reduced the zinc in its sunscreen. But is it really harmful?

Jessica Alba’s The Honest Company has come under fire recently after users of its sunscreens said they got sunburned despite applying the sunscreen as directed.According to NBC5 in Chicago, this might be due to the fact that the company has switched its sunscreen formula, reducing the amount of zinc it uses from 20% to 9.3%. Most zinc sunscreens contain between 18% to 25%.

NBC5 Chicago reported that The Honest Company said that it has been transparent about the amount of zinc it uses and that when it removed zinc, it added other ingredients to ensure the sunscreen was effective.

Here is a quick look at why zinc is a key ingredient in sunscreens:

What is it? Zinc is a trace mineral. The human body should contain about 2-3 grams of zinc, according to the US National Library of Medicine. If you are not getting enough zinc in your diet – through meats such as beef and pork – you could potentially suffer from a zinc deficiency.

What does it do? In sunscreens, zinc oxide (ZnO) particles are used to protect your skin from sunburn.

How does it do that? Nanoparticles of zinc oxide and titanium dioxide (TiO2) absorb ultraviolet light, which can cause cancer. As the Guardian reported last year, compared to other UV filters, these particles “are more stable – requiring less reapplication – and are low irritant and low allergen materials”.

When readers wrote to The New York Times asking about zinc-based sunscreens, Dr Doris J Day, clinical assistant professor of dermatology at New York University Medical Center, said:

Zinc oxide provides physical protection from damaging rays, absorbing primarily UVA light rather than scattering or reflecting it. It is also a mild antimicrobial and wound healing substance and is considered to be non-comedogenic.

What does the science say? Do not avoid zinc when buying sunscreen. According to Paul Wright, toxicology expert at RMIT University, these nanoparticles do not get past the outermost dead layer of human skin cells. Other research has also shown that if these nanoparticles do make it through the skin, the immune system collects and breaks down zinc oxide nanoparticles.

Zinc oxide is also one of the FDA approved ingredients when it comes to sunscreens. The recommendation is for up to 25% zinc oxide content.

What are the alternatives? While there are sunscreens out there – or recipes for homemade sunscreens – without zinc, experts do not recommend them.

The American Cancer Society includes zinc oxide, and titanium dioxide in a list of the only proven ingredients to protect against UVA rays. The Environmental Working Group, however, recommends avoiding sunscreen sprays and powders that contain zinc and titanium, and instead sticking to the lotions.

In an interview with Allure, Joshua Zeichner, a dermatologist in New York City, said that homemade sunscreens do more harm than good. Most of them are oil based and allow UV rays to penetrate the skin.

Cosmetic chemist Ni’Kita Wilson agreed.

“There’s a reason even the most natural companies have to include chemicals in their sunscreens,” she told Allure. “It’s for your safety. There’s a lot of chemistry that goes into an SPF.”