Build a solid foundation in science, formulation and product development—find out more!
Most Popular in:
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.
- Figure 1. Vernix caseosa covers newborn infants
- Figure 2. Lipid, free lipid extract and ceramide analyses
- Figure 3. Water loss profiles
- Figure 4. Water loss profiles of vernix caseosa films as a function of relative humidity
- Figure 5. Equilibrium water sorption-desorption curves
- Figure 6. Percent barrier recovery after tape stripping versus film permeability
- Figure 7. Moisture accumulation assessment
- Figure 8. Water release profiles
- Figure 9. Microgels and coating lipids
- Figure 10. Water release profiles of native VC and various biofilms
page 3 of 12
When it comes to studying the structural packing of the vernix caseosa lipids, the available literature is scarce. In 2000, Pickens et al. had already described the vernix caseosa as a mobile or fluid phase SC, suggesting hardly any barrier function at all.11 This was confirmed by the work of Rissmann et al.,15 who concluded—based on small angle X-ray diffraction work—that there was no well-defined, long-range ordering, such as the occurrence of lamellae stacks, visible in the vernix caseosa samples they studied. However, a small population of lipids formed a long-range ordering at room temperature that, in a later article from the same group, was shown to disappear at elevated temperatures; these changes were found to be reversible.17
Finally, Rissmann et al. describe, in a third article, that vernix caseosa lipids are able to form the long periodicity phase with similar spacing to the human SC.18 This phase has been shown by Bouwstra et al. to be essential for the barrier function of the SC.19 But the temperature required for the formation of the long periodicity phase is different for vernix caseosa than SC barrier lipids, which can be most likely attributed to the different fatty acid chain composition (especially the presence of branched fatty acid chains) and the resulting difference in physicochemical properties.18 From this, one can conclude that the barrier function of vernix caseosa in the womb is definitely different from and less pronounced than the SC, and possibly only functions via the waterproofing mechanism described by Youssef et al.4 However, once the baby is delivered, the barrier function of the vernix caseosa changes again, as will be discussed next.
Vernix caseosa Water-holding Capacity: The ‘Outside’ Story
Once a baby is delivered, vernix caseosa has two important external functions. First, it must regulate the newborn’s transepidermal water loss (TEWL) and second, it must maintain its body temperature. Most babies, however, are immediately cleaned after delivery—and rumor has it that midwives apply some of the vernix caseosa they remove to their own hands, rendering them soft and well-hydrated. This suggests good hydrating properties of vernix caseosa. As was demonstrated in a previous column, however, good skin hydration is not just a matter of sufficient water in the skin; hydration also relates to optimized barrier function.10
The SC of a newborn baby is still in the process of adapting to extra-uterine life20 and has therefore not yet matured. At certain body sites, this may manifest itself in excessive water loss, leading not only to a reduced enzymatic activity in the skin, but also a reduced body temperature. It must be mentioned here, however, that other investigators state that term newborns have a functionally superb epidermal barrier.21
Over the last decade, many investigators have studied the water-holding capacity of vernix caseosa.22-28 This bio-film indeed has a unique water-holding capability. Despite its high water content (about 80%), water is released slowly from vernix caseosa, which is comparable to the release of water from a water-in-oil emulsion, as shown in Figure 3. Here, the loss of water is measured as a function of time from vernix caseosa, a water-in-oil emulsiona and an oil-in-water emulsionb.