Violence in the Middle East. Child immigrants crossing into the US from Mexico. Ben Affleck as Batman.
If I asked you to name the day’s most controversial issue you might have guessed one of the above. However, you would have been wrong. Apparently nothing is as contentious as what controls oil production on your skin.
In a previous post on oily skin I reported on a 1974 study which indicated that the presence of oil on the skin’s surface sends a signal to the sebaceous glands to turn off. One astute reader, Kiera, was quick to point out that the study I cited is “old” and that the most comprehensive view of the literature confirms that skin does NOT have an external mechanism for regulating the level of sebum on the skin. More comments followed:
Lejla: “That study is old and has been falsified.”
Lyn: “Are the authors going to respond? Is the content of this post accurate or not?”
Ahj: “I also am very interested why Beauty Brains quote such a controversial study without further comments.”
Whew! Who knew this was such a touchy topic?
Why sebum production is so confusing
The controversy stems (at least in part) from the opinion of renowned dermatologist Albert Kligman who refuted this so called “Feedback Theory” in 1958. Kligman (and coauthor Shelly) said that “the sebaceous gland functions continuously, without regard to what is on the surface.” Yet, the theory once more gained credence in 1974 based on a paper titled “The regulation of sebum excretion in man.” (No word on how sebum is excreted in women.)
But *gulp* in 1976 the Feedback Theory was refuted again and there it stayed until new data became available in 1979. In the 1979 study, researchers found, after controlling as many variables as possible, that the excretion process does indeed slow down over time. If you read the paper you can see for yourself that the authors refuted arguments against the Feedback Theory which include:
- A wiping off effect
- A “run off” of sebum
- A resorption of sebum and changes in the physical property of sebum
They conclude by saying that “the Feedback Theory should not be too lightly dismissed.”
In 1981 the Feedback Theory deniers made a good case by reinforcing Kligman’s objections (“Sebum secretion and sebaceous lipids.” Dermatologic Clinics, Vol. 1, No. 3, July 1983.) I couldn’t find any more recent studies so I assume that the controversy rages on. (Of course I may have missed something so I welcome our readers to poke around in the literature for more recent studies which may trump this one.)
So is there an answer or not?
Could the answer to this controversy be a question of language? When Kligman raised his initial objections he used the term “secretion” which can mean either production or excretion. The authors of the 1979 study were careful to point out that they only studied the excretion of sebum (in other words the “arrival of sebum at the surface of skin.”) This is not necessarily exactly the same as sebum production which is the creation of sebum by sebaceous glands. So, could both parties be right? Maybe the sebaceous glands are unregulated (as Kligman says) but the mechanism by which the sebum reaches the skin’s surface IS regulated by some kind of feed back loop. Without further data, that’s my best guess and I hope it satisfies the hordes of passionate readers.
References:
Is the Excretion of Sebum Regulated ? H. Eberhardt and G. Trieb Arch. Dermatol. Res 266, 127-133 (1979)
http://www.acne.org/messageboard/topic/71047-still-more-evidence-against-the-feedback-theory/