42, 43), since as you age, your body becomes less efficient at producing vitamin D from the sun, and because the risks of sun exposure to your skin and your immune system are so high.Americans spent more than $7 billion on anti-aging treatments for the skin in 2008, according to the American Academy of Dermatology. But your most effective anti-aging treatment might be a $5 bottle of sunscreen—and not just because it protects your skin from wrinkles and other signs of sun damage. Too much ultraviolet (UV) radiation can actually suppress your immune system. Two kinds of UV wavelengths reach the earth: ultraviolet A (UVA) and ultraviolet B (UVB). Research indicates that UVB rays increase your risk of DNA changes that can develop into skin cancer, and UVA rays create free radicals that not only damage DNA but also impair your immune system, making it less able to defend against cancerous changes and other dangerous invaders. Those free radicals speed up the aging of your immune system, hastening the natural decline of your body’s defenses.
Exposure to immune-suppressing UVA rays causes a defect in the development of T cells (a type of white blood cell) that impairs their ability to become “long-term memory” cells, according to a 2010 study in the journal Photochemical & Photobiological Sciences. Australian researchers demonstrated that UVB rays have a similar effect. Memory cells allow your immune system to remember and defend against illnesses and bugs you’ve already encountered, such as chicken pox. Since your body gradually stops producing “naïve” T cells by the time you reach your mid-sixties, your immune system increasingly depends on existing memory T cells to keep you healthy as you get older.
On the other hand, sun exposure allows skin to synthesize vitamin D, which boosts immunity by affecting white blood cells’ response to infection, notes a 2010 study in Molecular and Cellular Endocrinology. That doesn’t give you a free pass to skip sunscreen, however. Experts point out that you’re better off getting vitamin D from foods and supplements (42, 43), since as you age, your body becomes less efficient at producing vitamin D from the sun, and because the risks of sun exposure to your skin and your immune system are so high.
Since both UVA and UVB rays suppress your immune system, look for sunscreens labeled “broad spectrum” that shield you from each. Apply 1 ounce (30 ml, or the amount in a shot glass) of SPF 15 sunscreen half an hour before heading outdoors—even on hazy days, since UV rays can penetrate cloud cover. If you have fair skin or burn easily, opt for SPF 30. Reapply every two hours (2). No sunscreen can block all UV rays, however, so some radiation still reaches skin and creates free radicals. Adding antioxidants to your sunscreen can neutralize age-accelerating oxidative damage. A 2009 study in the Journal of Investigative Dermatology found that antioxidant plant compounds called polyphenols, such as epigallocatechin-3-gallate (EGCG) from green tea, protect against UV-induced DNA damage and immune suppression, thanks to their ability to quench free radicals and regulate a protein that coordinates the immune response to infection. Look for bottles combining vitamins C and E and/or EGCG with a broad-spectrum sunscreen for the most effective protection.
Even better than sunscreen? Limiting your sun exposure, especially between 10 a.m. and 4 p.m., when the sun shines the strongest. Even darker-skinned people who don’t burn easily should seek shade whenever possible, since UV rays penetrate skin deeply to create immunity-lowering free radicals and DNA damage even without a visible sunburn. You might also wear a hat and sun-protective clothing if you’ll be outside for a while. Swap your baseball cap or golf visor for a broad-brimmed topper to shield your face and neck better. Wear tightly woven, loose-fitting, and dark-colored clothing, or purchase pieces specifically designed to offer sun protection. Such products tend to use very tightly woven fabrics and/or UV-absorbing chemicals applied to the fabric, and they should include an ultraviolet protection factor (UPF) rating that indicates how much of the sun’s UV radiation is absorbed (look for a rating of at least thirty). Wear and tear may reduce the garment’s sun protection, so follow the label’s care instructions closely. You can also wash chemical sunscreens into your regular clothes by adding a product like SunGuard to a load of laundry.
