Question of the Week Podcast

Question of the Week episode

Sun, 15th Apr 2012

Will my skin soak up the calories in skin cream?

skin, dermis (c) Grey's

This week we find out if a liberal slathering of oil based moisturiser makes up part of our daily calorie quota. Plus we ask, are monitor screens and e.books more than your standard page turner, leaving you tossing and turning and up all night?....

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Apparently it does occur in premature babies ...


http://medind.nic.in/ibv/t05/i3/ibvt05i3p255.pdf RD, Wed, 4th Apr 2012

In adults, the effect would be small:
- Skin surface area is smaller relative to volume, compared to children
- The layer of dead cells on the skin would reduce absorption of oils into the skin layer
- The skin does not have all the enzymes and pH conditions that the gut has to metabolise oils and fats. evan_au, Fri, 6th Apr 2012



can deliver lipids intravenously ... https://en.wikipedia.org/wiki/Total_parenteral_nutrition#Solutions

i.e. the oil just has to make it into the bloodstream. RD, Fri, 6th Apr 2012

I spoke with Prof Richard Guy at Bath University about this and he comments:

"Babies born prematurely have two important characteristics: (a) they are pretty small and, as you say, they have a high surface area to volume ratio, and (b) they have incompletely formed stratum corneum - that is, their skin barrier is not fully developed.  The reason for the latter is self-evident: in the womb, the baby is basically submerged in a water bath and is in no need of a barrier to water loss.  As the gestational period comes to its conclusion, however, and the foetus prepares for birth, the differentiation of the epidermis steps up a gear to generate a proper stratum corneum such that, on "popping out", the newborn has a skin barrier that's not much different from that of a healthy adult.

It's well-established in the literature and in clinical practice that premature babies have to be carefully monitored and maintained in well-controlled conditions, in particular, to stop excessive water loss across their skin.  Once has to be careful too with exposure to exogenous substances which may easily cross the less-than-fully-developed skin and cause potentially harmful effects.  The observation that rubbing oil on premature neonatal skin results in the appearance of some constituents in the blood is not too surprising therefore.  It's probable that the oil is also enhancing the weak skin barrier function in these babies and this will, in turn, improve their well-being.

Normal skin turnover means that we lose, on average, about one cell layer a day and that we always have a final layer of cells about to fall off the body.  However, with the exception of certain disease states where these layers of finally desquamating cells are not shed correctly, we do not build up large amounts of dead cells on the surface.  Further, when we apply lotions or creams, etc., the massaging in of the formulation almost certainly rubs off those soon-to-be-lost dead cells and they pose no really effective barrier to the uptake of material, therefore.

The skin and gut have completely different functions, of course.  The gut has evolved to be a an efficient mechanism by which we absorb nutrients from food and the pH, enzyme content, structure, and so on are highly developed to make this work.  This includes the absorption of fat which, at least in days gone by, was rather important in keeping Homo Sapiens alive.  In contrast, the skin has evolved to be a barrier, as described in my original response, and has no absorptive role in terms of keeping the organism alive.  As a result, it does not possess all those things which makes the gut so good at turning food into the building blocks that we need for life.

As an aside, though, it's fun to point out that the external skin and the gut (and by gut I would mean from the mouth to the anus) form a continuous, essentially uninterrupted surface, the functions of which are really distinct depending on where you are!

Hope that helps.  Best wishes,  R"

Thanks for your comments all!, Hannah nakedhannah, Mon, 16th Apr 2012

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