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"Wear sunscreen" is some of the most basic health advice you can get — right up there with eating fruits and vegetables. But standard sunscreen — the kind that comes out of the bottle white or cream colored and disappears into the skin — leaves out an important benefit, says Dr. Jenna Lester, associate professor of dermatology at the University of California, San Francisco.

Over the last decade or so, there's been more research into hyperpigmentation — which can show up as dark spots or patches — and melasma, a condition where brown or bluish-gray patches develop on the skin. These issues happen much more frequently for people with darker skin.

These conditions are not solely caused by ultraviolet radiation, says Dr. Adam Friedman, Professor and Chair of Dermatology at George Washington University. Evidence shows that radiation from visible light, which penetrates the skin more deeply than UV rays, can contribute to hyperpigmentation and melasma. Visible light has been shown to trigger erythema, or skin reddening, in lighter skin.

Most sunscreen products don't offer protection from visible light radiation.

"In dermatology, understandably, we have this focus on skin cancer," Lester says "And I think that focus sometimes tends to take people of color out of the discussion because it's something less likely to occur in people of color," she says.

Hyperpigmentation and melasma don't pose a danger to health, but "we can't underestimate the psychosocial emotional impact," says Friedman.

But tinted sunscreens, which have pigment to match a range of skin tones, do block visible light radiation.

 on tinted sunscreen published earlier this summer in the journal 

Photodermatology, Photoimmunology & Photomedicine 

found that tinted sunscreens outperform non-tinted products in protecting against damage from visible light.

 found that while over 90% of providers said that they counseled their patients about visible light protection, only about 10% made evidence-based recommendations.

The researchers, who included Dr. Friedman, want to see more research and standardized recommendations for visible light protection. And more choices of products: Some providers said the lack of a suitable range of tints got in the way of their patients using tinted sunscreen.

Understanding hyperpigmentation and melasma

Dark spots don't just appear on the skin out of nowhere. The process often starts with an inflammatory skin condition, most commonly acne, or with a bug bite or scratch. Friedman says the body's inflammatory response — meant to heal the wound — can also damage pigment cells in the skin, known as melanocytes.

These pigment cells come in packets called melanosomes. In darker skin, says Friedman, the packets are larger and more distributed and darker skin tones can be more prone to hyperpigmentation.

Aside from this inflammatory process linked to visible light radiation, there are other ways spots can appear on the skin. For instance age spots also called solar lentigo develop from sun exposure over time and are thought to be the result of ultraviolet radiation. Another benign skin growth called 

 is not connected to light radiation at all. Some definitions of hyperpigmentation include these and other conditions that 

, and the science on visible light radiation is still evolving.

People with lighter skin aren't immune to post-inflammatory hyperpigmentation but

"if you are someone with darker skin and you have acne and you're out in the sun, that's a recipe for longer lasting and more noticeable dark spots," Friedman says.

Dermatologists know less about melasma, which is an active inflammatory condition rather than a mark left behind. Hormones play a role, and sun exposure aggravates the condition, says Friedman.

Want visible light protection? Here's what to look for on a label

Components listed as active ingredients on a bottle of sunscreen or sun protective moisturizer are those that protect the skin from UVA and UVB radiation. So to tell if a product blocks visible light radiation too, you have to look further down the label.

The number one ingredient to look for when it comes to visible light protection is the chemical compound iron oxide, both Lester and Friedman agree. Iron oxide gives tinted sunscreen its color, and it's also commonly used to lend a skin-toney hue to concealer and foundation.

"Any tinted mineral sunscreen likely will filter out visible light," says Friedman.

How much iron oxide is enough? That's a tough one. "The trouble is that we don't really know what concentration is in there because it's still not listed as an active ingredient. For most sunscreen brands, it's proprietary how much is in there, so they won't even tell you if you ask them," Lester says.

She says that around 3% iron oxide likely offers the best protection. And she says it's safe to assume that sunscreens that are white or off-white in color don't include high enough levels of the compound to make the grade. To an extent, you can eyeball it – we're talking about visible light after all.

Friedman says tinted titanium dioxide also does a good job of scattering visible light. (Titanium dioxide also comes in a "transparent" version). Watch out, Friedman says, for sunscreens marketed as "ultra-shear or ultrafine." Those products contain nanoparticles of zinc oxide and titanium dioxide, which block UV radiation but are too tiny to scatter visible light.

There is some evidence that antioxidants like vitamin C are helpful too in protecting against visible light, Lester says.

Tinted sunscreens were originally designed not to confer visible light protection but to blend with your skin tone or serve as a makeup that doubles as sun protection. They can better match darker skin tones, says Friedman.

"I tend to hear people talk about ghostly or ashy looks for mineral-based sunscreen, like zinc, titanium," says Lester. "Tinted sunscreens containing iron oxide tend to mitigate that problem a little bit, but they certainly don't cover the diversity of dark skin tones that exist in the world," she says.

Lester points out that similar to Band-Aids, tinted sunscreen products that match darker skin have become available just in the last few years. "I would love for companies to develop even more deeply tinted sunscreen," she says.

Lester notes that if you can't find a tinted sunscreen in a shade you like, you can look for a foundation containing iron oxide and first apply non-tinted sunscreen and then layer over the foundation, which should provide some protection against visible light.

Dr. Friedman says that all things considered, he encourages patients to wear tinted sunscreen to prevent hyperpigmentation, even if they can't find a perfect color match.

"Given how disabling dark spots are to, I would say, every single patient that has them, it's a different mindset with respect to why you would use it versus not," he says.

Andrea Muraskin is a health and science journalist based in Boston. She writes the NPR Health newsletter.

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Most sunscreens protect skin from UV light but the tinted variety also block visible light. And that can be important for people with hyperpigmentation or melasma, especially those with darker skin.

Tinted sunscreen does something regular sun protection can't

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