防晒霜的另一种隐藏功能:抗皱

Dermatologists have been telling patients for years that using sunscreen regularly can protect skin against aging. Now there's research to back that up.

皮肤科医生多年来一直告诫患者，经常使用防晒霜能够防止皮肤老化。如今，这种说法有了研究证据的支持。

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《内科学年鉴》(Annals of Internal Medicine)上刊登的一篇论文中，研究人员指出，按指示每天涂抹防晒霜的人皮肤老化程度比被告知只是按照平时习惯使用防晒霜的人低24%。皮肤老化程度是以皮肤的皱纹和粗糙度来衡量的。

'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.'

马萨诸塞州切斯纳特希尔(Chestnut Hill)的皮肤科医生杰弗瑞•多弗(Jeffrey Dover)说：“这是我们鼓励大家使用防晒霜的绝佳依据。我每天都会引用这篇论文。”

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.

防晒霜长久以来一直被说成是抑制光老化（由日晒导致的皮肤变化）的方式。但论文作者称，以往的人体试验中并没有支持这种说法的有力证据。1995年发表的一项试验覆盖了35名曾罹患皮肤癌的人，该试验未发现防晒霜具有保护效果的证据（通过显微镜下皮肤活检来衡量）。但受具体操作和费用等因素影响，针对较大群体的大规模随机试验并未进行。

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.

该研究是一项长期性皮肤癌预防试验的组成部分，覆盖了903名55岁以下、居住在澳大利亚楠伯(Nambour)（靠近该国的阳光海岸(Sunshine Coast)）的成年人。研究人员给所有试验参加者发放了防晒系数(SPF)为15+的防晒霜。研究者随机选择其中半数的试验对象，要求他们每天在皮肤裸部位涂抹防晒霜，并在被水浸泡、大汗淋漓或在户外待几个小时后补涂防晒霜。另有半数的人被要求按他们自己平时的习惯使用防晒霜。

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.)

这项研究由澳大利亚政府资助。到试验结束时，被要求每天擦防晒霜的受试者中有77%的人一周至少使用三到四天，而控制组则只有33%的人使用（试验中使用的防晒霜是由一家防晒霜生产商提供的）。

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.

研究人员在研究刚开始时以及四年半后对受试者的手背取了硅胶印模。接下来，经过专门训练的评估人员按照从一到六的等级对手部印模的纹路和皮肤粗糙程度进行评分。澳大利亚昆士兰医学研究院(Queensland Institute of Medical Research)高级科学家、癌症和人口学研究负责人、该研究论文第一作者阿黛尔•格林(Ad口le Green)称，皮肤表面的受损情况能够反映出皮下组织的损伤。

Participants were under 55 to assure that aging effects were the result of sun exposure, not the natural aging process, Dr. Green said.

格林说，为了确保老化效应是由日晒，而不是由自然衰老过程引起的，试验参加者年龄都在55岁以下。

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.

她说，这些结果有“双重意义”，因为减少紫外线引起的皮肤损伤也会降低皮肤癌风险。

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.)

皮肤科医生表示，虚荣心是人们使用防晒霜的强大动力。佛罗里达州圣彼得斯堡(St. Petersburg)的皮肤科医生詹姆斯•斯潘塞(James Spencer)表示，对年轻人来说尤其如此，年轻人被晒伤可能会使他们在几十年后面临患皮肤癌风险。他说，与癌症风险相比，产生皱纹的风险通常更能促使人们改变行为（斯宾塞医生和多弗医生均未参与此项研究）。

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.

根据美国食品和药物管理局(U.S. Food and Drug Administration)去年实施的规定，只有广谱防晒霜──能同时防范长波紫外线和中波紫外线─和防晒系数在15或以上的防晒霜才可以声称能够降低皮肤提前老化和皮肤癌风险。格林说，这两种紫外线都与光老化和癌症有关联。不能同时防护这两种紫外线或者防晒系数在2到14之间的防晒霜只能声称有助于防止晒伤。

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，根据新规定，声称具有防水效果的产品必须说明使用者游泳或出汗时防晒效果能保持多久，是40分钟还是80分钟。此外，防晒霜(sunscreen)不能再被称为“日光隔离霜”(sunblock)，标签上也不能再单纯使用“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.'

斯潘塞建议人们使用防晒指数至少为30的防水广谱产品。他说：“别怕抹防晒霜，如果你抹得太薄，就达不到瓶子上说的防晒指数。”

'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.'

多弗补充称：“要找你喜欢的防晒霜，否则你是不会用的。不要等到夏天结束时还有一整管。”

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.

由于有试验证据显示每日口服抗氧化剂（如β胡萝卜素）能够减少日晒引起的皮肤损伤痕迹，该研究也考察了每天服用30毫克β胡萝卜素补充剂能否减缓皮肤老化。

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.

研究人员发现，服用补充剂者和未服用补充剂者并没有区别，不过研究人员表示，考虑到受试者的人数有限，他们不排除β胡萝卜素会对特定人群产生一定的微弱影响。