What's pH & Why Does It Matter For Your Skin?
You may have come across a skin care product that claims to be 'pH balanced' and maybe you didn't know what it meant.
Well, it's important, so pay special attention, especially if you're the type of person who prefers to do at-home, 'all natural' treatments. And pay extra special attention if your skin feels damaged (dry, easily irritated, sensitive, red, itchy, etc.).
I talk about pH a little bit in my video response to Sarah Therese's video on how she cleared her acne, but let me elaborate on it here. Because it's just that damn important.
The concept of pH was first introduced by a Danish chemist named Søren Peder Lauritz Sørensen in 1909, and then it was revised to the modern pH in 1924.
The exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation pH stands for "power of hydrogen", although it may also stand for “potential hydrogen”. That doesn't matter so much, though - as long as we know what the pH is a measure of.
pH is a measure of the acidity or alkalinity of a solution, the negative of the logarithm to base 10 of the activity of the hydrogen ion, on a scale from 0 to 14. 7 is considered neutral, while anything below 7 is considered an acid, and anything above is considered alkaline or basic.
pH measurements are important in medicine, biology, chemistry, agriculture, forestry, food science, environmental science,oceanography, civil engineering, chemical engineering, nutrition, water treatment & water purification, as well as many other applications.
But here we are concerned with the human body.
The pH of different cellular compartments, body fluids, and organs is usually tightly regulated in a process called acid-base homeostasis, and, contrary to popular belief, you cannot change to pH of your body (as each organ functions at different a pH) by eating a more "alkaline diet".
The pH value varies greatly within the body. Some parts are acidic, others are alkaline. For example, the stomach is loaded with hydrochloric acid, giving it a pH value between 2 and 3.5 (highly acidic). This is necessary to break down food. Human blood is always slightly alkaline, with a pH between 7.35 and 7.45. The blood pH value falling out of the normal range is very serious and can be fatal if untreated. However, this only happens during certain disease states, and has absolutely nothing to do with the foods you eat from day to day.
The variable skin pH values are being claimed, all in the acidic range but with a broad range from 4.0-7.0.
Many people say that the pH of healthy skin ranges from 4.5-6.5, others say from 4.5-5.5. Some say that 5.5 is the right pH, no lower and no higher.
To determine more accurately what skin pH is and should be, a multicentre study assessed the skin pH before and after refraining from showering and cosmetic product application for 24 hours. This saw the skin pH drop from 5.12 to 4.93, leading to the estimate that the "natural" pH of skin is, on average, below 5 (which is lower than many people believe, but which is actually in line with a large number of other reports).
(You might be thinking then, that the solution is to simply stop washing your face and using all products - and certainly this does sometimes help people clear up their skin, but the bad outweighs the good in this case, as we then begin to accumulate debris, dead skin and other microorganisms on our face. A better solution would be to simply use appropriately-formulated products to maintain our skin's pH!)
So, after removal of the stratum corneum layers, surface pH starts at about 4.5–5.3, increasing by about 2–3 units until it reaches 6.8 in the lower stratum corneum.
So when people tell you that a healthy skin pH can be around 6.0 - tell them they're wrong, and refer them to this blog post with all of these lovely links proving that healthy skin is slightly acidic skin, around 4.5-5.3 - :)
Now that we know what pH is and what a healthy skin pH level should be, what does this have to do with what we apply to our skin?
The skin pH is affected by a great number of endogenous factors (skin moisture, sweat, sebum, anatomic site, genetic predisposition and age). Use of cosmetic products, especially soaps, cleansers and other topical products like antibiotics, have a profound influence on skin surface pH.
The increase (becoming more alkaline or less acidic) of the skin pH irritates the physiological protective 'acid mantle', changes the composition of the cutaneous bacterial flora (in the case of alkaline products, it can actually increase the amount of acne-causing bacteria!) and the activity of enzymes in the upper epidermis, which have an acid pH optimum. The dissolution of fat from the skin surface may influence the hydration status leading to a dry and squamous skin.
The acid skin surface pH has antimicrobial activities, which may help make it inhospitable to acne-causing bacteria, as we discussed earlier, so its maintenance and healthy function is important to consider when using products. So skin with pH values below 5.0 is in a better condition than skin with pH values above 5.0, to fight off acne-causing bacteria; an acid skin pH (4-4.5) keeps the resident bacterial flora attached to the skin, whereas an alkaline pH (8-9) promotes the dispersal from the skin. We need those bacterial flora to maintain healthy skin - plain and simple!
A central role for the acidic milieu also has relevance to the integrity of the barrier function, from normal maturation of the stratum corneum lipids through to desquamation. Changes in the pH and the organic factors influencing it appear to play a role, not only in the pathogenesis, prevention and treatment of irritant contact dermatitis, but also of atopic dermatitis and ichthyosis and in wound healing. So, not only can improperly formulated (too low or too high pH) products or home remedies (like lemon (which is only slightly less acidic than gastric acid, which is a digestive fluid, formed in the stomach - ick!) or baking soda (too alkaline)) cause your skin to be more susceptible to things like acne and irritation, but it can also make your acne stick around longer by making it harder to heal.
Clearly it is in our skin's best interest to maintain its "slightly acidic" pH of around 4.5-5.3.
Did you know that even the tap water you use may actually be affecting your skin's pH level? In Europe, the pH value of plain tap water is generally around 8.0. If our skin's "healthy" pH value is around 4.5-5.3, clearly plain old tap water is far too alkaline (you can of course purchase testing strips to determine if your tap water is too alkaline), which may be disrupting our skin's acid mantle. One study found that using tap water with a pH of 8.0, for example, will increase the skin's pH (make it more alkaline) for up to 6 hours after application before it will return to it's normal value. And if we are washing our skin 2x a day with this alkaline water which disrupts our skin's ability to function, we aren't giving it any time to ever recuperate.
This is why some people opt for the use of toners after cleansing, to restore pH, or the use of distilled water, instead.
Another study found that applying a slightly acidifying product to acneic skin decreased the skin surface pH (bringing the acidity to normal ranges), and decreased the number of acne lesions. So while we don’t want our skin care products to be too acidic (like lemon), or too alkaline (like baking soda or lye), we do want our skin care products to be slightly acidic, to maintain the integrity of the acid mantle, which will help our skin to keep acne at bay.
If you're unsure if a product is acidic or alkaline - just look it up!
Here are a few examples of pH balanced cleansers that you may want to try! pH balanced toners, moisturizers and spot treatments are also important. Believe it or not, there are products out there that are too alkaline for the skin (even Cetaphil!).
Get the derma|e Soothing Cleanser here.
Get the Alba Botanica Pineapple Enzyme Cleanser here.
Get the Coconut Milk Cleanser here.
Recognizing factors that alter skin pH and selecting products that preserve the acid mantle is of prime importance for anyone suffering from acne, dry skin, irritated skin, sensitive skin, etc. And therefore, the use of skin cleansers, moisturizers and other products with a proper pH of about 4.5-5.5 would be most suited and relevant in treating and preventing skin conditions like acne and dermatitis.