防曬霜的另一種隱藏功能:抗皺
Dermatologists have been telling patients for years that using sunscreen regularly can protect skin against aging. Now there's research to back that up.
皮膚科醫生多年來一直告誡患者，經常使用防曬霜能夠防止皮膚老化。如今，這種說法有了研究證據的支持。
In a study published in the Annals of Internal Medicine, researchers showed that people instructed to apply sunscreen every day showed 24% less skin aging, as measured by lines and coarseness of the skin, than those told to use the cream as they usually do.
在《內科學年鑑》(Annals of Internal Medicine)上刊登的一篇論文中，研究人員指出，按指示每天塗抹防曬霜的人皮膚老化程度比被告知只是按照平時習慣使用防曬霜的人低24%。皮膚老化程度是以皮膚的皺紋和粗糙度來衡量的。
'This is great fodder for us to encourage people to use sunscreen, ' said Jeffrey Dover, a dermatologist in Chestnut Hill, Mass. 'I will quote this paper every day.'
馬薩諸塞州切斯納特希爾(Chestnut Hill)的皮膚科醫生傑弗瑞•多弗(Jeffrey Dover)說：“這是我們鼓勵大家使用防曬霜的絕佳依據。我每天都會引用這篇論文。”
Sunscreen has long been touted as a way to stave off photoaging, or changes to the skin caused by sun exposure. But there wasn't hard evidence in humans to support the claim, study authors said. A trial published in 1995 involved 35 people with past skin cancer and found no evidence of sunscreen's protective effect, measured by looking at skin biopsies under a microscope. But larger, randomized trials open to the larger community hadn't been done, for logistical and cost reasons.
防曬霜長久以來一直被說成是抑制光老化（由日曬導致的皮膚變化）的方式。但論文作者稱，以往的人體試驗中並沒有支持這種說法的有力證據。1995年發表的一項試驗覆蓋了35名曾罹患皮膚癌的人，該試驗未發現防曬霜具有保護效果的證據（通過顯微鏡下皮膚活檢來衡量）。但受具體操作和費用等因素影響，針對較大羣體的大規模隨機試驗並未進行。
This study, part of a long-running skin-cancer-prevention trial, covered 903 adults younger than 55 living in Nambour, Australia, near the country's Sunshine Coast. All study participants were given sunscreen with a sun protection factor (SPF) of 15+. Half were randomly to be instructed to apply the sunscreen daily to exposed areas, reapplying after water immersion, heavy sweating or several hours spent outdoors, while half were told to use it as they normally would.
該研究是一項長期性皮膚癌預防試驗的組成部分，覆蓋了903名55歲以下、居住在澳大利亞楠伯(Nambour)（靠近該國的陽光海岸(Sunshine Coast)）的成年人。研究人員給所有試驗參加者發放了防曬係數(SPF)爲15+的防曬霜。研究者隨機選擇其中半數的試驗對象，要求他們每天在皮膚裸部位塗抹防曬霜，並在被水浸泡、大汗淋漓或在戶外待幾個小時後補塗防曬霜。另有半數的人被要求按他們自己平時的習慣使用防曬霜。
By the end of the study, which was funded by the Australian government, 77% of those told to use sunscreen daily were using it at least three to four days a week, compared with 33% of the control group. (The sunscreen was provided by a sunscreen manufacturer.)
這項研究由澳大利亞政府資助。到試驗結束時，被要求每天擦防曬霜的受試者中有77%的人一週至少使用三到四天，而控制組則只有33%的人使用（試驗中使用的防曬霜是由一家防曬霜生產商提供的）。
Researchers took silicone impressions of the backs of participants' hands at the beginning of the study and after 4½ years. Trained assessors then graded the patterns of lines and skin coarseness on the hand impressions on a scale of one to six. The damage seen on the surface of the skin reflects the tissue damage underneath the skin, said Adèle Green, senior scientist and head of cancer and population studies at Queensland Institute of Medical Research in Australia and lead author of the study.
研究人員在研究剛開始時以及四年半後對受試者的手背取了硅膠印模。接下來，經過專門訓練的評估人員按照從一到六的等級對手部印模的紋路和皮膚粗糙程度進行評分。澳大利亞昆士蘭醫學研究院(Queensland Institute of Medical Research)高級科學家、癌症和人口學研究負責人、該研究論文第一作者阿黛爾•格林(Ad口le Green)稱，皮膚表面的受損情況能夠反映出皮下組織的損傷。Participants were under 55 to assure that aging effects were the result of sun exposure, not the natural aging process, Dr. Green said.
格林說，爲了確保老化效應是由日曬，而不是由自然衰老過程引起的，試驗參加者年齡都在55歲以下。
The results have a 'double significance, ' she said, since the reduced skin damage from UV rays also translates to a lower risk of skin cancer.
她說，這些結果有“雙重意義”，因爲減少紫外線引起的皮膚損傷也會降低皮膚癌風險。
Dermatologists said vanity is a strong motivating force when it comes to sunscreen use. That's particularly true for young people, whose sunburns may put them at risk for skin cancer decades later, said James Spencer, a dermatologist in St. Petersburg, Fla. The threat of wrinkles is often a more powerful behavior-changer than the threat of cancer, he said. (Neither Dr. Spencer nor Dr. Dover was affiliated with the study.)
皮膚科醫生表示，虛榮心是人們使用防曬霜的強大動力。佛羅里達州聖彼得斯堡(St. Petersburg)的皮膚科醫生詹姆斯•斯潘塞(James Spencer)表示，對年輕人來說尤其如此，年輕人被曬傷可能會使他們在幾十年後面臨患皮膚癌風險。他說，與癌症風險相比，產生皺紋的風險通常更能促使人們改變行爲（斯賓塞醫生和多弗醫生均未參與此項研究）。
Rules implemented last year by the U.S. Food and Drug Administration say that only sunscreens that are broad-spectrum─protecting against both UVA and UVB rays─and that have an SPF of 15 or higher can claim to reduce the risk of early skin aging and skin cancer. Both types of rays are implicated in photoaging and cancer, Dr. Green said. Products that don't protect against both types of rays or that have an SPF between 2 and 14 can claim only to help prevent sunburn.
根據美國食品和藥物管理局(U.S. Food and Drug Administration)去年實施的規定，只有廣譜防曬霜──能同時防範長波紫外線和中波紫外線─和防曬係數在15或以上的防曬霜纔可以聲稱能夠降低皮膚提前老化和皮膚癌風險。格林說，這兩種紫外線都與光老化和癌症有關聯。不能同時防護這兩種紫外線或者防曬係數在2到14之間的防曬霜只能聲稱有助於防止曬傷。
The new rules also say that products claiming water resistance must say how long a user can expect to get that protection while swimming or sweating, either 40 minutes or 80 minutes. And sunscreens can no longer be called 'sunblocks' or be labeled as 'waterproof' or 'sweatproof.'
此外，根據新規定，聲稱具有防水效果的產品必須說明使用者游泳或出汗時防曬效果能保持多久，是40分鐘還是80分鐘。此外，防曬霜(sunscreen)不能再被稱爲“日光隔離霜”(sunblock)，標籤上也不能再單純使用“防水”(waterproof)或“防汗”(sweatproof)等字眼。
Dr. Spencer recommends that people look for water-resistant, broad-spectrum products with an SPF of at least 30. 'Don't be shy about putting it on, ' he said. 'You're not getting the SPF on the bottle if you're putting it on too lightly.'
斯潘塞建議人們使用防曬指數至少爲30的防水廣譜產品。他說：“別怕抹防曬霜，如果你抹得太薄，就達不到瓶子上說的防曬指數。”
'Look for something you like, or you won't use it, ' Dr. Dover added. 'And don't have a full tube by the end of the summer.'
多弗補充稱：“要找你喜歡的防曬霜，否則你是不會用的。不要等到夏天結束時還有一整管。”
Since experimental evidence has suggested that antioxidants consumed orally, such as beta carotene, can reduce signs of sun-related skin damage, the study also looked at whether a daily 30-milligram beta carotene supplement could protect against skin aging.
由於有試驗證據顯示每日口服抗氧化劑（如β胡蘿蔔素）能夠減少日曬引起的皮膚損傷痕跡，該研究也考察了每天服用30毫克β胡蘿蔔素補充劑能否減緩皮膚老化。
Researchers found no difference between those who took the supplement and those who didn't, though because of the number of study participants, researchers said they couldn't rule out a small effect one way or the other in certain groups of people.
研究人員發現，服用補充劑者和未服用補充劑者並沒有區別，不過研究人員表示，考慮到受試者的人數有限，他們不排除β胡蘿蔔素會對特定人羣產生一定的微弱影響。
