From cleansers to creams and serums to sunscreens, the skin care aisle is bursting with products that promise to make our skin look brighter, softer, younger, better. But which products are must-haves, and which are unnecessary? Should you shell out extra cash for “clean” cosmetics? And is sunscreen really that important?

从洗面奶、面霜、精华液到防晒霜，护肤品的货架上到处都是承诺让我们的皮肤看起来更亮、更柔软、更年轻、更好的产品。但是哪些产品是必须的，哪些是不必要的?你应该为“干净”的化妆品多花钱吗?防晒霜真的那么重要吗?

We asked a trio of UCSF dermatologists our burning questions about skin care to find out which products should earn a spot on our shopping lists.

我们向三位加州大学旧金山分校的皮肤科医生询问了我们关于皮肤护理的迫切问题，以找出哪些产品应该在我们的购物清单上占有一席之地。

MYTH #1 — I need to follow a complex — and expensive — skin care routine to keep my skin healthy as I age.

误解1:随着年龄的增长，我需要遵循复杂而昂贵的护肤程序来保持皮肤健康。

Actually, a simple drugstore moisturizer is the most important product, aside from sun protection, in your anti-aging skin care routine, says Katrina Abuabara, M.D., an associate professor of dermatology at UCSF with an interest in eczema. Moisturizer helps protect the skin barrier, a pivotal function of our body’s largest organ.

事实上，在你的抗衰老皮肤护理程序中，除了防晒，一个简单的药店润肤霜是最重要的产品，加州大学旧金山分校皮肤科副教授Katrina Abuabara医学博士说，她对湿疹很感兴趣。保湿霜有助于保护皮肤屏障，这是我们身体最大器官的关键功能。

As we get older and the immune cells in our skin amass more exposure to toxins, allergens, and pollutants, our skin’s ability to function as a barrier declines, Abuabara says. This can cause low-grade skin inflammation, with symptoms including redness and dryness. Inflamed immune cells from the skin may spread throughout the body, causing systemic inflammation, which can lead to a host of serious health problems.

Abuabara 说，随着年龄的增长，皮肤中的免疫细胞越来越多地接触毒素、过敏原和污染物，皮肤作为屏障的能力就会下降。这会引起轻度皮肤炎症，症状包括发红和干燥。皮肤上发炎的免疫细胞可能会扩散到全身，引起全身性炎症，从而导致一系列严重的健康问题。

For instance, patients with moderate to severe eczema, a skin condition characterized by a red and itchy rash, have higher rates of cardiovascular disease. Last year, Abuabara was the lead author of a study showing that adult patients with eczema have a 27 percent increased risk of dementia.

例如，患有中度至重度湿疹(一种以红色和发痒皮疹为特征的皮肤状况)的患者患心血管疾病的几率更高。去年，Abuabara是一项研究的主要作者，该研究表明，患有湿疹的成年患者患痴呆症的风险增加了27%。

For older adults and those with dry skin, one of the best ways to prevent skin inflammation is to apply moisturizer. Experts at UCSF and elsewhere are studying whether moisturizer use could actually ease inflammation-related problems beyond the skin. Peter Elias, M.D. ’67, UCSF dermatology professor emeritus, found that applying Vaseline petroleum jelly to mice reduced the levels of inflammation in their blood. A small study by Elias and other researchers suggested the same might be true of humans.

对于老年人和那些皮肤干燥的人来说，防止皮肤炎症的最好方法之一就是使用保湿霜。加州大学旧金山分校和其他地方的专家正在研究使用保湿霜是否真的能缓解皮肤以外的炎症相关问题。1967年医学博士、加州大学旧金山分校皮肤病学名誉教授彼得·伊莱亚斯发现，在老鼠身上涂抹凡士林凡士林油可以降低它们血液中的炎症水平。伊莱亚斯和其他研究人员进行的一项小型研究表明，人类可能也是如此。

“I don’t think we’re going to cure dementia with Vaseline,” Abuabara says. “But putting moisturizer on older adults may help as part of a general strategy — and it’s so low cost and easy and safe that it is something people could consider as part of elder care.”

“我不认为我们会用凡士林来治愈痴呆，”Abuabara说。“但在老年人身上涂抹润肤霜作为总体策略的一部分可能会有所帮助，而且它成本低、简单、安全，人们可以把它作为老年人护理的一部分。”

So, using moisturizer is a good idea, but how does one choose from the countless products available? The products with the most moisturizing power are ointments like Vaseline and oils, Abuabara says. Creams are the next most moisturizing, then lotions and gels. “It just depends on how dry you are and what type of product you prefer,” she says. “Everyone’s a little different.”

所以，使用保湿霜是一个好主意，但如何从无数可用的产品中选择呢?Abuabara说，最保湿的产品是像凡士林和油这样的软膏。面霜是第二保湿的，然后是乳液和凝胶。她说:“这取决于你的干燥程度和你喜欢的产品类型。每个人都有点不同。”

MYTH #2 — If I wear sunscreen all the time, I won’t get the vitamin D that I need.

误解2:如果我一直涂防晒霜，我就无法获得所需的维生素D。

While it’s true that 90 percent of our vitamin D comes from sun exposure, that’s hardly a get-out-of-jail-free card when it comes to sun protection, says Lindy Fox, M.D., a UCSF professor of dermatology who cares for hospitalized patients with complex skin conditions. Even with a sunscreen routine, most healthy people get enough unintended sun exposure that they don’t need a vitamin D supplement.

虽然我们体内90%的维生素D确实来自于阳光照射，但说到防晒，这很难说是一张逃脱牢狱的卡，医学博士Lindy Fox说，他是加州大学旧金山分校的皮肤学教授，负责照顾患有复杂皮肤病的住院病人。即使定期涂抹防晒霜，大多数健康人也会受到足够的意外阳光照射，因此不需要补充维生素D。

Experimental research — studies with a control group and an experimental group – has shown that using sunscreen reduces vitamin D absorption, Fox says. But observational studies — in which researchers observe what participants do naturally – indicate that sun protection doesn’t cause people’s vitamin D levels to drop.

Fox 说，实验研究——对对照组和实验组的研究——表明，使用防晒霜会减少维生素D的吸收。但观察性研究——研究人员观察参与者的自然行为——表明，防晒不会导致人们的维生素D水平下降。

That might be because most people don’t use enough sunscreen. One ounce — about the size of a shot glass — is the amount of sunscreen required to cover the entire body once, Fox says. And if you’re swimming and sweating, you should reapply sunscreen every two hours. That means a typical adult on a beach vacation should use up an entire three-ounce bottle of sunscreen in a single day.

这可能是因为大多数人没有使用足够的防晒霜。Fox说，一盎司——大约一个小玻璃杯的大小——是一次覆盖全身所需的防晒霜量。如果你在游泳和出汗，你应该每两个小时重新涂抹一次防晒霜。这意味着一个典型的海滩度假的成年人一天应该用掉整整一瓶三盎司的防晒霜。

Even if you spend most of the day inside, UVA rays penetrate your home, office, and car windows unless a UVA-specific blocker has been added to the glass.

即使你一天中大部分时间都呆在室内，UVA射线也会穿透你的家、办公室和车窗，除非在玻璃上添加了特定的UVA阻挡剂。

Unprotected sun exposure is a known risk factor for skin cancer, so Fox says sun protection is a must for everyone. “You should be using sunscreen every day, just like you brush your teeth,” she says. “Sunscreen should go on sun-exposed areas, including, for ultimate sun protection, your face, your chest, your hands, your arms.” (And don’t forget to reapply it before a lunchtime walk.)

无保护的阳光照射是皮肤癌的一个已知的风险因素，所以福克斯说防晒对每个人都是必须的。她说:“你应该每天使用防晒霜，就像你刷牙一样。”“防晒霜应该涂在暴露在阳光下的地方，包括你的脸、你的胸部、你的手和你的手臂，以达到最终的防晒效果。(别忘了在午餐散步前再涂一次。)

Supplementing a sunscreen routine with sun-protective clothing, such as rash guards and wide-brimmed hats, is also a good idea.

在日常防晒措施的基础上加上防晒服，比如防皮疹服和宽边帽，也是一个好主意。

MYTH #3 — My dark skin protects me from skin cancer, so I can skip sunscreen.

误解3:我的黑皮肤可以保护我不患皮肤癌，所以我可以不涂防晒霜。

Sorry, but people with darker skin tones still need sun protection – though perhaps not for the same reasons as those with lighter skin, says assistant professor of dermatology Jenna Lester, M.D., who directs UCSF’s Skin of Color Program.
加州大学旧金山分校肤色项目的负责人、皮肤病学助理教授詹娜·莱斯特博士说，很抱歉，肤色较深的人仍然需要防晒——尽管原因可能与肤色较浅的人不同。

It’s true that melanin, a natural pigment that gives color to skin and is more abundant in darker-skinned people, is protective against skin cancer, Lester says. That’s probably why melanoma is less common in people with darker skin, though it is more deadly in those who are diagnosed with it.

莱斯特说，黑色素是一种赋予皮肤颜色的天然色素，在皮肤较深的人身上含量更丰富，确实可以预防皮肤癌。这可能就是为什么黑色素瘤在肤色较深的人群中不太常见，尽管对被诊断患有黑色素瘤的人来说，它更致命。

Based on what dermatologists know today, sunscreen use does not prevent melanoma in Black patients. But focusing sun protection education largely on skin cancer prevention ignores the reasons why people of color should wear sunscreen, Lester says. “We center the concerns of white patients in the dermatology experience,” she says. “We don’t really talk about sunscreen as much when we’re talking about discoloration or uneven skin tone or the visible signs of sun damage in someone with dark skin.”

根据皮肤科医生今天所知道的，使用防晒霜并不能预防黑人患者的黑色素瘤。 Lester说，但是把防晒教育主要集中在预防皮肤癌上，忽视了有色人种应该涂防晒霜的原因。她说:“我们把白人患者的关注点集中在皮肤科体验上。我们谈论皮肤变色或肤色不均或皮肤黝黑的人晒伤的明显迹象时，我们并不会过多地谈论防晒霜。”

Regular sunscreen use can help prevent a host of pigmentary disorders, including melasma, a condition in which darker patches or spots appear on the face.

经常使用防晒霜可以帮助预防许多色素紊乱，包括黄褐斑，一种出现在脸上的深色斑块或斑点。

People with darker skin are less likely to develop wrinkles caused by sun exposure, Lester says, but they can develop an uneven skin tone. “A daily sunscreen practice can help prevent that from ever being a problem,” she says.

Lester说，肤色较深的人不太可能因阳光照射而产生皱纹，但他们可能会产生不均匀的肤色。她说:“每天涂抹防晒霜可以帮助防止这成为一个问题。”

MYTH #4 — “Clean,” “natural,” or organic skin care products are better.

误解4:“清洁”、“天然”或有机护肤品更好。

Nope. In fact, products touted as “clean,” “natural,” or organic are often worse for the skin. “People use products they think are better because they’re called ‘clean,’” Fox says. “They end up coming to us with sick skin full of rashes, allergies, and other problems.”

不。事实上，标榜“清洁”、“天然”或有机的产品往往对皮肤更有害。“人们使用他们认为更好的产品，因为它们被称为‘干净’，”Fox说。“最后，他们带着长满皮疹、过敏和其他问题的病态皮肤来找我们。”

What shouldn’t be on the ingredient list?

什么不应该出现在配料表上?

Watch out for substances with the potential to cause irritation or skin reactions, such as fragrances, essential oils, and certain preservatives like methylisothiazolinone and propylene glycol.

注意可能引起刺激或皮肤反应的物质，如香水、精油和某些防腐剂，如甲基异噻唑啉酮和丙二醇。

The ingredients in these products tend not to be well studied, Fox says. And cosmetics don’t have to be approved by the U.S. Food and Drug Administration before being sold. “The problem with the clean beauty movement,” she says, “is that there’s no definition of ‘clean.’”

Fox 说，这些产品中的成分往往没有得到很好的研究。化妆品在销售前不需要经过美国食品和药物管理局的批准。“清洁美容运动的问题在于，”她说，“没有‘清洁’的定义。”

Here’s how this dermatologist defines a good skin care product: It contains ingredients that are good for the skin, that have scientifically proven efficacy, and that won’t cause allergies or irritations. Some of these include retinoids for anti-aging, niacinamide for hydrating and restoring the skin barrier, ceramides for locking in moisture, and squalane, a skin softener that improves elasticity and reduces visible signs of aging.

以下是这位皮肤科医生如何定义好的护肤品:它含有对皮肤有益的成分，经过科学证明的功效，不会引起过敏或刺激。其中包括抗衰老的类维生素a，保湿和修复皮肤屏障的烟酰胺，锁住水分的神经酰胺和角鲨烷，一种皮肤柔软剂，可以提高弹性，减少明显的衰老迹象。