2 things beauty consultants might not tell you (that you wish you knew!)
How many of us have tried being tested in those ‘skin analyzer’ machines and got scores like ‘oh you’re skin is too dry’, ‘too oily’, ‘too much old skin accumulated’? 😪
Try asking ‘what exactly is the machine measuring?’ or by what metrics is ‘too dry’, ‘too oily’? I don’t think many can confidently answer that.
Read on so next time you can make sense of all those numbers! But before we are ready to jump into the numbers, first we need to know what makes our skin happy.
Let's get this straight!!
Some important concepts here:
(1)
Aging skin =/= unhappy skin.
There are many dimensions to aging and this process is inevitable. Nobody can escape from aging skin (what is aging skin anyway??😂), but there are ways to slow it down!
(2)
Our skin will be most happy if it is allowed to perform the function it’s supposed to do.
The skin is our largest organ. It is the ‘first layer of defense’ between internal and external environment. Its first and foremost function, is NOT to make us look pretty and all glamorous with porcelain complexion, but act as a PROTECTION barrier. (More on other functions, [1])
Key to happy skin = good barrier function
So far, I’ve only been reading up on a few academic papers and trying to figure out what are the key aspects that is related to keeping skin healthy. I’m sure there are a lot more than what is listed below, but these 2 factors I feel are the most ‘relatable’ to us:
(1) pH
Skin has a natural pH of ~5 (+/- 1 depending on the research, but one thing for sure it’s acidic). Keeping the acidic surface pH is important for good skin condition.
Now I’m not sure what will happen if we make skin more acidic than it should be, what what I found is that - on the opposite spectrum: if we make it more alkaline (note: if your natural skin pH is 4.7, if you increase its pH to 6 (still acidic), it is still ‘more alkaline’ than your natural pH), things like this happen:
- Your ‘acid mantle’ impairs. ‘It might mean it’s easier to be infected, red, dry, itchy, etc.Acid mantle’ produces anti-bacterials, and beats harmful bacteria, so our skin is less likely to get unhappy (*not the most technically correct terms here but it’s easier to understand this way).
- Skin is also more susceptible to SLS (sodium lauryl sufate) irritation. BTW, SLS is commonly found in most shampoos, face wash & shower gel!!
**
What can affect your skin pH?
Your cleanser, moisturizer, or even tap water!! Normally tap water is slightly alkaline, because acidity might corrode pipes. [2] Soaps are most likely alkaline. It’s better to check if your cleanser is acidic/alkaline!
[3] found that it takes 6 HOURS for the skin to return to its natural pH after washing face with tap water, or shower gel of pH 6, and even longer for soap (which in this case is more alkaline than the shower gel). The length of time, of course, will dependent on the difference between your natural skin pH & the cleanser pH. But if your skin’s pH never had enough time to recover to its natural pH, problems might happen - you will suffer from more irritation, dryness, etc.
There are also studies that children living in an area with higher water hardness (more alkaline) is more likely to have eczema.
**
Sebum is actually acidic.
Our skin actually has a self-regulatory system to go back to its natural (acidic) pH. So perhaps why your face keeps producing sebum is because your skin is too alkaline!
(**All of the above info on pH is from [3])
(2) Hydration level
It’s actually funny how beauty consultants just generally tell you how ‘moist’ your skin is, because that is only one part of the story. You can have super hydrated skin, but your skin will still be dry.
We live in external environment with 40-60% relative humidity, whereas physiological conditions inside our body is usually ~99% RH. This means that we will continue to lose water had we not have any skin barrier. That’s why people calculate transepidermal water loss (TEWL). We lose about 100-150ml of water per day per sq.m. of skin of healthy skin [5].
So ideally, you want sufficient hydration of skin, and low TEWL so that you don’t lose water from skin. (*note that I didn’t say ‘high hydration’ because too high level of hydration might not be a good thing.) Natural hydration of SC is around 30-50% of its dry weight [5] - that’s why you really need to ask what the machines are measuring when you’re at a beauty counter. Is the number weight? %? If it is a %, % of what???
But why do we need hydrated skin to begin with?
The hydration of skin stratum corneum (SC), basically the outmost layer of skin, is crucial in regulating the barrier properties, appearance, and enzymatic activity [4]. What exactly is enzymatic activity? [5] & [6] say that it is related to desquamation, i.e. a process which your skin sheds old cells. So well hydrated skin will kind of indirectly aid desquamation, which is great because, at the end of the day, we want new skin! We don’t want the new skin cells to bury under the old skin that doesn’t go away!
Factors affecting your TEWL:
TEWL is relative. It depends on the difference of skin hydration level vs the outside humidity. This can be impacted by the temperature, time of day, windspeed, etc.
As small as an adhesive tape on skin can impact your TEWL. The TEWL rate is higher than before even after 4 days of stripping off the tape : O [7]
- The exact purpose of moisturizers are to keep TEWL low!!
So what does this all mean?? 🤷
Yea, so what does all of this mean to us?
(1) It is important to maintain a healthy level of hydration on skin.
Measuring moisture levels at beauty consultant counters without understanding your TEWL is useless. TEWL is dependent on your environment vs your skin’s own hydration level, so it’s totally rational to have different creams for different seasons.
(2) Try not to exfoliate or scrub too much - it destroys the natural skin barrier.
Skin cycle goes on a ‘bottom-up’ direction, i.e. skin cells are generated at the bottom of the skin and the new cells gradually move up to the outmost layer, then shedded off. Whatever you do at the top layer, doesn't really help with stimulating new cell growth. So think again when you buy that Dermes exfoliation package…
The skin has its own mechanism to renew - we have a 28-day skin cycle (roughly) and while it slows down as we age, there are other ways to maintain skin cycle such as diet & sleep & exercise.
(3) Get your pH strips ready
Get your pH strips that you probably haven’t touched again since primary school and check the pH of the cleansing agent, moisturizer & the tap water that you use!!!
Next up:
Stay tuned for the next post on:
- How to select a good moisturizer?
- How to increase hydration level of skin?
- Is there any racial differences in terms of our skin?
- Does diet play a role in maintaining healthy skin?
Reference:
[1] https://en.wikipedia.org/wiki/Skin#Functions
[2] http://www.freedrinkingwater.com/water-education/quality-water-ph-page2.htm
[3] - Lambers, H., Piessens, S., Bloem, A, Pronk, H. & Finkel, P. (2006). Natural skin surface pH is on average below 5, which is beneficial for its resident flora. The International Journal of Cosmetic Science, 28, 359-370.
[4] - Sparr, E., Millecamps, D., Isoir, M., Burnier, V., Larsson, A. & Cabane, B. (2012). Controlling the hydration of the skin through the application of occluding barrier creams. The Journal of Royal Society Interface, 10: 20120788.
[5] - Bouwstra, J.A., de Graaff, A., Gooris, G.S., Nijsse, J., Wiechers, J.W. & van Aelst, A.C. (2003). Water distribution and related morphology in human stratum corneum at different hydration levels. The Society of Investigative Dermatology, 120, 750-758.
[6] - Bouwstra, J.A., Wouter, H., Groenink, W., Kempenaar, J.A., Romeijn, S.G. & Ponec, M. (2008). Water distribution and natural moisturizer factor content in human skin equivalents are regulated by environmental relative humidity. Journal of Investigative Dermatology, 128, 378-388.
[7] - Dykes, P.J. (2002). What are meters measuring? International Journal of Cosmetic Science, 24, 241-245.
