A醇保養品紅什麼？美女皮膚科醫師教你如何挑選A醇，最強A醇保養大全

A醇保養品紅什麼？美女皮膚科醫師教你如何挑選A醇，最強A醇保養大全

By Dr. Chiachi Hsu

By徐嘉琪醫師

A醇為何那麼受歡迎？早在1995年，A酸就被FDA核可有減緩光老化和細紋的功效。身為皮膚科醫師，多年來一直被教育維他命A對皮膚有抗老、美白、控油、改善毛孔粗大等多種好處，也有很多實驗可證明其功效，是可以同時解決多重肌膚問題、且能擦一輩子的好成分。不過，10年前若想要在台灣尋找以A醇為主打的保養品為很難，即使在歐美也需要特地尋找才可能買到。不過這兩年，越來越多品牌推出A醇保養品，我非常樂觀其成，也很期待。提醒大家，維他命A類保養品畢竟是比較刺激、不穩定的成分，我也整理常被問到的A醇相關問題，協助大家找到最有效、最安全、最適合自己的A醇保養品。

A: Vitamin A is a group of highly nutritious organic compounds. They are essential nutrients for the body with different parts requiring different forms of vitamin A. For example, retinal is important for your eyes, and retinol is involved in embryonic development. Retinoic acid is most relevant to dermatologists because it is the only vitamin A ingredient that can kick in while activating the epidermal cells.

Vitamin A is fat-soluble. It is stored in the form of retinyl palmitate in the body, but has to be metabolized into retinol, then retinal, and lastly, into retinoic acid to become useful to the skin. So what are the effects of retinoic acid on the skin? To begin with, it can promote the growth and differentiation of the epidermal cells from the stratum basale so that the stratum corneum is more orderly layered. It also assists in the removal of old and dead skin cells, making the skin look smoother and glowing. Next, retinoic acid can reach further down to activate fibroblasts so as to help the synthesis of collagen and protect collagen and elastin from being easily destroyed by the sun. As a result, retinoic acid can improve problems such as the thinning of the skin and loss of elasticity caused by aging. As for brightening skin tone, retinoic acid can inhibit melanin production, making the skin look clearer and illuminating while improving spots. Since it can inhibit the sebaceous gland from secreting excessive sebum, retinoic acid is also known for controlling oily skin and resisting acne.

You may wonder why it is not retinoic acid that is being added to skincare products, since it’s the only vitamin A ingredient active in the skin and with so many benefits. Why is retinol grabbing all the attention instead? This is mainly because retinoic acid is very irritating and can only be used with the advice of dermatologists or other specialists. Restrained by regulations, retinoic acid cannot be incorporated into at-home treatment. As previously mentioned, the conversion order of different forms of vitamin A into retinoic acid is: retinyl palmitate → retinol → retinal → retinoic acid; the fewer the steps, the more effective, but also more irritating and unstable. Retinyl palmitate due to a longest conversion pathway is the mildest and serves better as a supporting role; retinal causes strong irritation and was previously patent-protected, so it has not been widely applied. And thus, it comes down to retinol with potency and irritation in between retinyl palmitate and retinal. No wonder retinol has stood out in recent years.

Q2：選擇A醇保養品時該注意什麼？濃度是不是越高效果越好？

A：市面上很多A醇保養品會標濃度，其實我覺得濃度僅供參考，當然保養品要有效活性成分必須有一定的濃度，但產品的基質及包裝也很重要。例如杏仁酸等酸類成分，雖然有些產品濃度高到20%、25%、30%好像很厲害，但若產品本身pH值不夠酸的話，濃度再高效果也要大打折扣。A醇也類似，因為它是脂溶性成分，基質應該要含有油脂、比較滋潤，如果產品的質地做得很水，例如做成化妝水或很水的精華液，當中的A醇應該無法發揮太多功效。另外，A醇很不穩定，包裝一定要是不透光的真空瓶，所添加的A醇才不會因被空氣氧化、被光線分解而失效。

依目前法規，保養品添加A醇沒有濃度上限，但通常有效濃度在0.1%至1%，這次DR.WU推出的新一代超A醇雖然是A酯、A醇、A醛三種成分加在一起，但1.5%濃度已經算高。另一個觀察重點是產品的顏色，A醇的原料應該是淡黃色的，產品的顏色應該也是淡黃色比較有效，如果是白色或透明，有可能是添加濃度太低，或加了很多色料把原本的顏色蓋住。

A: Lots of retinol products on the market specify concentration levels. I actually find concentration to be less of a consideration. Of course, the active ingredients of a product need to reach a certain concentration to be effective, but the product’s base material and packaging are equally important. For example, acidic ingredients such as mandelic acid might seem impressive when it accounts for 20%, 25%, or even 30% of a product. Yet, if the product itself has a pH value that is not acidic enough, however high the concentration is, the result it can deliver is still greatly reduced. The same goes for retinol. Since retinol is a fat-soluble ingredient, the product’s base material should contain oil and should be more nourishing. If the product’s texture is watery, such as the texture of a toner or watery serum, the retinol within is probably not able to deliver much of its effects. Furthermore, retinol is very unstable. The packaging has to be opaque and airless so that retinol does not become ineffective due to oxidation and light degradation.

According to current regulations, there’s no max limit to the concentration level of retinol in skincare products, but usually the effective strength ranges from 0.1% to 1%. DR.WU’s new release of the next-generation Tri-Retinoid is featuring a pretty high strength at 1.5%, even though it is a combination of three ingredients: retinyl palmitate, retinol, and retinal. Another key point to observe is the product’s color. The color of retinol’s raw material should be a pale yellow. If the product’s color is also a pale yellow, it is probably more effective; if it is white or transparent, it might be because the concentration is too low, or too many colorants are added and covered the original color.

Q3：肌膚比較敏感的人可以用A醇保養品嗎？還是用最溫和的A酯就好？

A：A酯當然是維他命A衍生物中最溫和的，但它要轉換成可被皮膚利用的A酸需要經過太多道程序，最後效果會被遞減很多。如果是容易敏感泛紅的肌膚，還是可以選擇相對較溫和的A醇來使用，如果購買的廠牌有不同濃度的話，當然建議從最低濃度開始試用起，如無不適應再進階往上一個濃度。一罐保養品認真使用通常1-3個月可用完，而A醇是可以用一輩子的好成分，因此可以慢慢嘗試不用急。如果喜歡的品牌只有推出一個濃度，敏感肌膚可以從做1天休2天開始，也就是第1週先擦個兩、三次，如果沒有刺激紅腫再提高頻率為1個禮拜擦三、四次，最後進階到天天晚上使用。

Q4：A醇、A酸、杏仁酸、水楊酸等都可以煥膚、縮毛孔，請問分別適合什麼膚質？建議怎麼選？

A：我覺得可以由產品的基質來決定，例如前面提到A醇是脂溶性，產品的質地通常比較油，如果你是痘痘肌、油性肌，或正處於青春期這種油脂分泌比較旺盛的階段，就不適合這類較滋潤的產品，建議先從杏仁酸、水楊酸的產品開始使用。如果是輕熟齡肌膚，皮膚可能相較於青春期比較乾燥，但仍會長一些粉刺痘痘，又想要有一些抗老化效果，就很適合使用A醇。簡而言之，青春痘可選擇杏仁酸、成人痘選擇A醇。

Q5：A醇不能跟什麼一起用？網路上有爬到文說和其他酸類並用能讓保養效果更加乘。

A：因為A醇本身已經很有活性和刺激性，保險起見不要跟太刺激的產品，如酸類或美白類等有宣稱療效的保養品一起使用，因為這類產品通常比較刺激，如果要一起用的話，最好等到自己肌膚比較適應A醇後再添加。其實這一題沒有標準答案，因為皮膚狀況百百種，要看每個人的膚質，以酸類為例，如果你得天獨厚皮膚是比較厚又比較偏油的人，使用其他酸類也已一段時間都沒有任何不適，要漸進式地加入A醇一起試試也是可以的。但就我門診觀察，大部分女性的肌膚都比較偏敏弱，單用A醇已經很不錯。

Q6：使用A醇保養品後泛紅、脫皮該怎麼辦？什樣的脫皮、刺痛算不正常？A醇一定要脫皮才算有效？

A：使用A醇後如果有稍微脫皮的現象，只要加強保濕即可；若出現一點泛紅，建議先暫停使用A醇並加強保濕，等皮膚恢復正常再重拾A醇；若出現乾癢刺痛症狀，建議先去看醫師、擦點藥膏比較好。其實，擦A醇保養品不是要脫皮才表示有效，居家保養建議還是溫和一點，不需要把皮膚弄得好像果酸換膚一樣大脫皮，這種徹底破壞再重建的保養工程建議還是在診所進行、由醫師監控比較安全。

Q7：擦A醇為何有些人會有爆痘期？會持續多久？

A：痘痘的未爆彈就是粉刺，如果你有許多肉眼可見的閉鎖性粉刺或黑頭粉刺，在擦酸類、A醇這類可幫助角質代謝的成分時，很容易爆痘，因為這些成分會讓粉刺加速代謝出來。爆痘期的長短要看本身粉刺的量，如果粉刺很多的話爆痘3到6個月是有可能的，粉刺比較少的人大約忍1個月就會有所改善。使用A醇期間如爆痘嚴重，建議去看醫師、吃點消炎藥。