A new study has found that applying sunscreen every day can do more than lower your risk of skin cancer — it can also drastically reduce the effects of photoaging（光老化）, or the way frequent sun exposure can make your skin look older. And there's more good news: Even if you slacked off on sunscreen in your youth, middle age isn't too late to benefit from slathering it on.

 

"It has been a source of frustration¹ for us that for some sections of the community, the sun-safe message does not seem to be getting through," Dr. Adele Green, a professor at the Queensland Institute of Medical Research at the University of Queensland in Australia, said. "We now know that protecting yourself from skin cancer by using sunscreen has the added bonus of keeping you looking young."

 

The study, published this week in the Annals of Internal Medicine, also looked at whether taking beta-carotene supplements could have an anti-aging effect. Beta-carotene is a type of antioxidant known as a carotenoid（类胡萝卜素）, and has been linked to a reduced risk of skin cancer.

 

For the randomized-controlled trial, the researchers assigned 903 participants to one of four groups: Those who used broad-spectrum sunscreens daily and take 30 milligrams of beta-carotene, those who used daily sunscreen and took a placebo², those who took the beta-carotene but only used sunscreen periodically, and those who used sunscreen periodically and took a placebo. (All participants were age 55 or younger; the researchers decided³ it would not be ethical⁴ to have a group in which participants used no sunscreen at all.)

 

The two daily sunscreen groups used UVA/UVB blocking products with a SPF (sun protection factor) of 15 or higher; they applied⁵ the product to their head, neck, arms, and hands each morning after bathing, and reapplied it every few hours. The other two groups applied sunscreen where and when they thought they needed it.

 

The researchers tracked participants for four and a half years, and used putty-like skin molds to document fine lines and wrinkles. They found that the groups using sunscreen every day showed 24 percent less skin photoaging than those who only applied it periodically. The results were the same regardless of age, so even the middle-aged⁶ participants benefited from regular sunscreen use.

 

"The cost-effectiveness of promoting daily sunscreen use based on skin cancer prevention alone is probably substantially higher after accounting⁷ for the additional prevention of skin photoaging," wrote the researchers in their report.

 

Taking beta-carotene had no overall effect on skin aging, the researchers added.

 

In 2012, the U.S. Food and Drug Administration decided that sunscreen makers⁸ could state on the labels that their products reduced the risk of skin cancer and skin aging if used as directed, as long they also advised people to take other precautions, like reapplying sunscreen at least every two hours (more often if you're sweating or swimming), avoiding going out when the sun is most intense (usually between 10 a.m. and 2 p.m.), and wearing long-sleeved shirts, pants, and broad-brimmed hats to shield the skin when possible.

 

If you only have a few minutes in the morning, it makes sense to apply sunscreen to the areas most likely to see the sun — your face, neck, and hands. All types of sunscreen, even "sport" or "waterproof⁹" formulas, need to be reapplied regularly, and you should wear sunscreen even if you spend all day driving or working indoors, advises Dr. Jaliman, the cosmetic¹⁰ dermatologist¹¹（皮肤科医生）.

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