Sunscreens are designed to protect your skin in the sun, filtering out harmful ultraviolet radiation. They are still the first and best line of defense against premature aging from the sun, but which ones can really be considered anti-aging?

Sunscreens can help prevent three types of damage from the sun’s rays:

• Sunburn 
• Skin cancer
• Premature aging

Whether these creams and lotions can help you avoid wrinkles, age spots and other symptoms of premature skin aging depend on which type of ultraviolet radiation they block.

While both UVA and UVB contribute to skin damage, UVA rays are now known to cause premature skin aging—resulting in wrinkles, changes in skin texture, and uneven pigmentation. UVB is primarily responsible for skin burning.

Surprisingly, little research on whether sunscreen really prevents skin aging existed prior to 2013—proving, at least, that sunscreen use slows or prevents skin aging.

To assess whether sunscreen can indeed prevent wrinkles in humans, Australian researchers conducted a randomized controlled trial using data from The Nambour Skin Cancer Prevention Trial. Published in the Annals of Internal Medicine, the study compared 903 adult subjects divided into four groups:

1. Those instructed to apply broad-spectrum sunscreen to their head, neck, arms, and hands each morning (and again after sweating or bathing)
2. Those who could apply the same sunscreen whenever they wished
3. Subjects receiving a beta-carotene supplement each day
4. Those who were given a placebo supplement

After four and a half years, the researchers analyzed latex impressions taken from the backs of the subjects’ hands. After correcting for factors like amount of sun exposure and smoking (which can also prematurely age skin), they found that those adults who used the broad-spectrum sunscreen daily showed “no detectable increase” in skin aging.

What’s more, skin aging—such as coarser skin and more wrinkling—during the study period was found to be 24 percent less among subjects in the daily sunscreen group when compared with subjects using sunscreen products only on a discretionary basis. Supplementation with beta-carotene had no overall effect on skin aging.

The American Academy of Dermatology (AAD) recommends a sunscreen with an SPF of at least 30. Also be aware of sunscreen ingredients. Ingredients which filter out UVA rays, in particular, include Avobenzone (Parsol 1789) and Benzophenones. Ingredients aimed at filtering UVB rays include PABA, ​cinnamates, and salicylates.

Sunscreens containing zinc oxide and titanium dioxide also provide UVA rays.

Whichever product you choose should be applied liberally (about one ounce or 15 ml) and often (every two hours or so). Since no sunscreen is completely waterproof, you should reapply after swimming or activities that cause you to sweat.

-Very Well