We know there are a wide variety of substances which can be absorbed through the skin and metabolized,(some which spring immediately to mind are nicotine, sunlight to make vitamin D, fentanyl) but research about whether or not calorically dense substances such as fatty acids can be successfully absorbed and used is still very preliminary.
There is some preliminary research indicating it may be possible to use transcutaneous absorbtion of lipids from certain oils as a nutrtional supplement in preterm babies.
Transcutaneous absorption of a mixture
of coconut oil and meadowfoam oil in
preterm babies has been successfully
demonstrated for the first time. The
variations observed in the amount and
the number of marker fatty acids is
probably due to the dynamic state of
triglycerides which are continuously
metabolized. Coconut oil has
predominantly short chain and
saturated fatty acids. These are
normally present in the serum of an
individual, diet being one of the
however, with regard to this particular data it is important to note:
The skin of the preterm neonate has
increased permeability as compared to
full term babies
Also, there is not yet a clear understanding of which fatty acids are best absorbed, indicating that some may absorbed at better rates than others possibly due to their structure
The fatty acids with two double bonds
(C20 ∆5,13) appears to be better
absorbed as compared to fatty acid
with single double bond
Of course, the relatively modest effects shown in this study only indicate that there appears to be some evidence for a plausible mechanism by which this occurs. It's still a long way away from determining if it a reasonable and effective way to supplement nutrition.
Given that this study was performed on premature neonates, extrapolation of this data with regard to older children and adults seems unwise to me at this point. Also, it would seem unlikely that transient amounts found in the localized application of various lotions and creams would have any tangible effect, and would probably only be able to shown by taking repeated blood draws before and after the application of one of these creams or lotions. It certainly would not be likely to have any effects noticeable outside perhaps, of a laboratory specifically looking for a serological rise in a certain compound.