The mineral calcium is well-known for its key role in bone health, teeth and bodily organs, including the skin, where it regulates skin's many functions. Most calcium in the skin is found in the outermost layer of skin (the epidermis) where it has been demonstrated to play an important role in barrier function repair and skin homeostasis 1 (self-replenishing process where the number of cell divisions within the skin compensates for the number of cells lost 2.) Within the epidermis, keratinocytes have a different need for calcium concentrations.
Despite the continuous renewal of the epidermis (almost every 60 days the epidermis renews itself completely, replacing more than 80 billion keratinocytes in the body of an average adult) our skin eventually succumbs to aging, as the turnover rate of the keratinocytes slows down dramatically. Aging is associated with thinning of the epidermis, elastosis, loss of melanocytes associated with an increased paleness of the skin and a decreased barrier function. As the differentiation of keratinocytes is strictly calcium dependent, calcium also plays an important role in the aging epidermis. Recently it has been shown that the epidermal calcium gradient in the skin that facilitates the proliferation of keratinocytes and enables their differentiation is lost in the process of skin aging 3.