Did you know that the surface of our skin is acidic? That we have a sour skin surface, like vinegar or lemon juice? Scientists have long known that we are covered by an acid mantle. But how the epidermis – the outer layers of skin – achieves this feat, conferring a pH of 5.0 or less to our skin surface, when the cells of our body and the blood and fluids bathing those cells have a more neutral pH of ~7.4, has until recently been something of a mystery.
To our surprise, as we were studying the characteristics of epidermis in relation to skin pigmentation, we noted that the pH of darkly pigmented stratum corneum is lower – that is, it is more acidic – than the surface of lightly pigmented skin. We saw that the pH of darkly pigmented skin was lower by about a half a unit – from ~5.0-5.5 in lighter skin to ~5.0-4.5 in darker skin . While that may seem like a small difference, it is actually rather huge. Differences in skin pH are a bit like those in earthquakes measured on the Richter scale, because both are logarithmic scales. Thus, a change of half a pH unit denotes a 50-fold more acidic environment! [Read more…] about Our Sour Skin Surface