Vernix Caseosa: The Ultimate Natural Cosmetic?

By: Johann W. Wiechers, PhD, JW Solutions; and Bernard Gabard, PhD, Iderma

Posted: August 31, 2009, from the September 2009 issue of Cosmetics & Toiletries.

Many research articles have been published since the turn of this century investigating the origin, composition, function and potential benefits of vernix caseosa. Not only does this research provide an understanding of the formation of perfect young skin, some of it can be translated into benefits for the cosmetic industry. The present review summarizes the current knowledge of vernix caseosa and discusses the underlying principles by which vernix caseosa operates; this can be applied in moisturizing and barrier-enhancing products, although the proteolipid biofilm itself cannot be used directly on the human body. The most important characteristic of vernix caseosa is its controlled degree of occlusivity—neither too much nor too little.

Vernix caseosa
Vernix caseosa is the creamy white, viscous biofilm that surrounds a newborn’s body during birth (see Figure 1). The Latin words vernix caseosa mean varnish and cheese-like, respectively, and indeed, sometimes the whole body is covered in this whitish cream during delivery. The vernix caseosa is produced during the last trimester of gestation as a remnant of the original periderm. It provides a temporary skin barrier that is suitable for the aqueous environment in utero, with active transport mechanisms between the amniotic fluid and embryo by virtue of its microvilli situated at the top of its surface.

Periderm cells are replaced continuously until 21 weeks of gestation when they are completely shed and replaced by the stratum corneum (SC). The shed periderm cells are mixed with secretions from the sebaceous glands within the epithelial walls to form vernix caseosa.¹ At the same time, the fetal lungs mature, which requires amniotic surfactant levels to increase. This in turn causes the vernix caseosa to detach from the fetal skin surface, contributing to the turbidity of the amniotic fluid at the end of pregnancy.²

While the exact function of vernix caseosa is still under debate, a multitude of different functions have been suggested, and in some cases identified. These can be divided into prenatal, during birth and postnatal functions. Prenatal functions include: waterproofing, since due to the low surface energy, vernix caseosa is highly unwettable;³ the facilitation of the skin formation in utero;¹ and protection of the fetus from acute or sub-acute chorioamnionitis (an inflammation of the outer (chorion) and inner (amnion) fetal membranes due to a bacterial infection).^{4, 5} During delivery, vernix caseosa acts as a lubricant while postnatally, it exhibits antioxidant, skin cleansing,⁶ temperature-regulating⁷ and antibacterial properties.⁸

Other possible prenatal roles have been suggested, such as facilitating the colonization of skin with microorganisms after birth,3,9 but for the cosmetic formulator, the most interesting properties of vernix caseosa are its skin moisturizing and skin barrier-enhancing properties. While a previous column linked the presence of orthorhombic skin lipid packing with good skin hydration,10 this column steps further back to examine how young, healthy skin is created.