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Does sebum help "moisturize" the skin??

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#41 bryan

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Posted 24 November 2009 - 10:27 AM

QUOTE (toomuchaccutane @ Nov 23 2009, 11:17 AM) <{POST_SNAPBACK}>
Thanks for posting this Bryan. So, what they are saying is that you would need atleast 10 times the amount of oil on a subject with already very oily skin to make a difference in transpiration of water?


To make something approaching a significant difference. Yes. Exactly!

QUOTE (toomuchaccutane @ Nov 23 2009, 11:17 AM) <{POST_SNAPBACK}>
Also, I didn't exactly understand what Kligman's findings were in relation to sebum and its effect on hair. What did he find in that study. The sebum was not needed or it was?


You didn't understand it, for the simple reason that I didn't bother to TELL you what it is that Kligman and his colleagues found! smile.gif The only reason I mentioned it at all was just to provide another example of how dermatogists (even Kligman!) can make assumptions about what they only think they know, without bothering to put it to a careful physical test, just like what those doctors in New York told you about how sebum is (supposedly) a "moisturizer".

Just to satisfy your curiosity, I'll tell you about what it is they found: it had nothing at all to do whether or not hair "needs" sebum, it just had to do with the exact way that sebum gets onto hair, in the first place. The assumption had always been that sebum just naturally flows along the length of hair, coating it uniformly, by a kind of "wicking" or capillary action. But Kligman and his colleagues did some careful testing that completely disproved those notions. They simply couldn't get sebum to flow along the length of a hair, no matter WHAT they tried. It was almost as if sebum has a natural aversion to hair! smile.gif The only conclusion they could draw from all that is that sebum gets onto hair only from actual physical contact, like when we touch or scratch our heads, comb our hair, sleep on a pillow, etc. They were so surprised to see that result, they admitted they were "incredulous". But any good doctor or scientist should alway question what he knows, or simply thinks he knows.

#42 bryan

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Posted 24 November 2009 - 11:00 AM

Hey, I found an old post of mine on another site where I had actually copied that same passage from the study! That would be from: "Studies on the Effect of Shampoos on Scalp Lipids and Bacteria", A. M. Kligman, K. J. McGinley, and J. J. Leydon, from the book Hair Research Ed. by Orfanos, Montagna, Stuttgen. Copyright Springer-Verlag Berlin Heidelberg 1981.

Refatting of Hair

Apart from the amount of sebum on the hair is the fascinating question of how it gets there. Hardly anyone has thought to look into the matter for the answer seems too obvious from the anatomy of the pilosebaceous unit. What could be more natural than to suppose that the sebum, excreted into the follicular canal, simply spreads up the hair shaft and uniformly coats it. Credit to Eberhardt for the imagination to question the obvious and for the elegantly simple methods employed in its refutation (Eberhardt 1976). When a droplet of sebum is placed on hair none of the lipid moves away; further, sebum will not creep along the surface when a terminal hair is placed in a capillary filled with sebum. We were incredulous and thought that the hair might first have to be moistened. However, we too found that sebum would not spontaneously spread out when droplets were placed on previously immersed hairs held in an atmosphere saturated with water. Further, we strung hairs in close parallel array on a wire frame, thinking that sebum placed at one end would migrate between the hairs by capillarity. Wetted or dry, the sebum showed not the slightest inclination to spread over the hairs as visualized by exposure to osmium tetroxide vapors. It seems an inescapable conclusion that the hairs become greased by mechanical transfer, from the scalp surface to the hairs, and from hair to hair. The hair acquires sebum by direct contact. The dispersal of sebum from the surface would be facilitated by combing and brushing, by wearing a hat, by rubbing the fingers through the hair, etc. Resilient, easily bendable thin hair would have a greater chance of contacting sebum than straight, stiff, widely-spaced hairs. Refatting of the hair is thus complex and will vary greatly from individual to individual.

It is logical to expect that that the segment closest to the scalp would have a greater chance of mechanical pick-up of sebum oozing out of the follicles. We did, in fact, find that in a 9-cm fiber, divided into thirds, the greatest amount of lipid was on the proximal third and the least on the distal. We considered the possibility that there might be a preferential separation of sebum components as the hair became refatted. However, it was found that the composition of lipid on the hairs was exactly the same as on the surface and was the same at various distances from the surface.


#43 toomuchaccutane

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Posted 24 November 2009 - 01:57 PM

QUOTE (bryan @ Nov 24 2009, 12:00 PM) <{POST_SNAPBACK}>
Hey, I found an old post of mine on another site where I had actually copied that same passage from the study! That would be from: "Studies on the Effect of Shampoos on Scalp Lipids and Bacteria", A. M. Kligman, K. J. McGinley, and J. J. Leydon, from the book Hair Research Ed. by Orfanos, Montagna, Stuttgen. Copyright Springer-Verlag Berlin Heidelberg 1981.

Refatting of Hair

Apart from the amount of sebum on the hair is the fascinating question of how it gets there. Hardly anyone has thought to look into the matter for the answer seems too obvious from the anatomy of the pilosebaceous unit. What could be more natural than to suppose that the sebum, excreted into the follicular canal, simply spreads up the hair shaft and uniformly coats it. Credit to Eberhardt for the imagination to question the obvious and for the elegantly simple methods employed in its refutation (Eberhardt 1976). When a droplet of sebum is placed on hair none of the lipid moves away; further, sebum will not creep along the surface when a terminal hair is placed in a capillary filled with sebum. We were incredulous and thought that the hair might first have to be moistened. However, we too found that sebum would not spontaneously spread out when droplets were placed on previously immersed hairs held in an atmosphere saturated with water. Further, we strung hairs in close parallel array on a wire frame, thinking that sebum placed at one end would migrate between the hairs by capillarity. Wetted or dry, the sebum showed not the slightest inclination to spread over the hairs as visualized by exposure to osmium tetroxide vapors. It seems an inescapable conclusion that the hairs become greased by mechanical transfer, from the scalp surface to the hairs, and from hair to hair. The hair acquires sebum by direct contact. The dispersal of sebum from the surface would be facilitated by combing and brushing, by wearing a hat, by rubbing the fingers through the hair, etc. Resilient, easily bendable thin hair would have a greater chance of contacting sebum than straight, stiff, widely-spaced hairs. Refatting of the hair is thus complex and will vary greatly from individual to individual.

It is logical to expect that that the segment closest to the scalp would have a greater chance of mechanical pick-up of sebum oozing out of the follicles. We did, in fact, find that in a 9-cm fiber, divided into thirds, the greatest amount of lipid was on the proximal third and the least on the distal. We considered the possibility that there might be a preferential separation of sebum components as the hair became refatted. However, it was found that the composition of lipid on the hairs was exactly the same as on the surface and was the same at various distances from the surface.


Bryan,

Thanks again for all the great research you gather to help me further understand that my lack of sebum doesn't matter. But I just wanted to make sure that you agreed with this. Do you feel that sebum is as useless for the skin as it is for the hair on a humans head? Basically, can a person have healthy hair without sebum?

#44 toomuchaccutane

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Posted 24 November 2009 - 05:39 PM

Also,

In that excerpt you included with the transpiration of water loss. What would the numerical number of someone who has really oily skin in the units they used "(mg/cm^2)." Like, i think the last one was about .6. Would that even be way more than a person with extremely oily skin. Is 3.7mg/cm^2 more than 10 times the amount of a person with oily skin, or ten times the amount of a person with average sebum production?

The reason i ask is because i used to have extremelyyy oily skin. So i am curious to know if maybe my skin was oily enought that it was effective in preventing epidermal water loss. I sure hope it wasn't because i would be said if i got rid of something that was really useful for this dry skin i have now. Sorry again for all the questions. But you're the only educated person i find on this site that gives me actual facts, not opinions!

Adam

#45 bryan

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Posted 18 October 2012 - 01:48 AM

I'm bumping this thread, just to provide it to new members here at acne.org who haven't seen it yet! Posted Image

#46 What1f

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Posted 11 May 2013 - 04:47 PM

Hate to flame, but you don't have any idea what you're talking about. Sebum keeps you young and delivers antioxidants to your skin, mainly vitamin e which is significant to skin. Sebum also keeps your eyes moist and protects them from debris. Keeps your hair shining, and if you must know sebaceous glands also moisturize your genitalia. Accutane is the absolute dumbest drug ever invented. If you're thinking about accutane, don't

#47 Toro

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Posted 18 May 2013 - 09:49 AM


 

What1f, on 12 May 2013 - 08:37, said:

Hate to flame, but you don't have any idea what you're talking about. Sebum keeps you young and delivers antioxidants to your skin, mainly vitamin e which is significant to skin. Sebum also keeps your eyes moist and protects them from debris. Keeps your hair shining, and if you must know sebaceous glands also moisturize your genitalia. Accutane is the absolute dumbest drug ever invented. If you're thinking about accutane, don't

Oh... Better discard every piece of scientific evidence sited thus far in this thread, then.

 

Step back a moment and think about the assumptions you are making. Why are you so adamant that sebum 'keeps you young,' that it delivers antioxidants and Vitamin E, that it keeps your hair shining?

 

I know at first glance it might seem counter-intuitive to claim that this oil, which most people immediately associate with moisture, does not in fact have much of a use even for moisturising the skin - but have you taken a closer look at the scientific literature, some of which is on this thread and more of which users like Bryan have posted elsewhere on these forums? If you do, you'll realise the reality is far more complex, and that there are many misconceptions about the whole role the sebaceous gland supposedly plays. You’ll also realise that the gland is the sole means of transmission for all acne, regardless of its underlying cause – it’s a gland that causes many, many problems but serves little useful function, giving us virtually none of the benefits it’s often been falsely credited with.

 

Also, the 'sebum' you refer to on the eyes is produced by the meibomian glands, which although related to sebaceous glands are quite distinct - they produce a different mixture of oils and waxes and serve a different purpose altogether. The substance they produce stops evaporation of some of the lower layers of fluids on the surface of the eye. The eye is a very different organ from the skin and these glands are outside the scope of this discussion altogether. A dysfunction of these glands is not necessarily related to dysfunctions of the sebaceous glands on skin. An acne treatment aimed at reducing or stopping sebum production would not be intended to target these glands, in the same way that an electrolysis treatment to remove facial hair on women would not be targeted at removing the eyelashes at the same time - they serve different purposes for very different organs. Facial hair is of little to no use for modern females, but eyelashes are certainly useful (and look nice). Similarly, sebaceous glands on the skin have little use, but meibomian glands are useful. If a treatment harmed these meibomian glands as well as the sebaceous glands on the skin, it would be an unwanted side effect in need of attention, because it could result in dry or sensitive eyes.

 

Accutane is, in fact, a good illustration of a common misconception most people have about sebaceous glands. Now, we know full well that accutane will frequently give very dry skin as a side effect, amongst many other unpleasant ones. And, of course, it's true that it clears up acne by reducing the production of sebum (although that is not its only method of action). But the immediate link most people draw between the two - dry skin and less sebum - simply isn't valid. The dry skin side effects of accutane have virtually nothing to do with reduced levels of sebum, however tempting it is to believe so. All the evidence points to other, more complex reasons which are unrelated to the sebaceous gland at all. But so common is this incorrect attribution that you will even find non-specialised doctors, e.g. GPs posting short general advice articles on the internet, making this incorrect statement - something along the lines of 'because the glands produce less oil .... dry skin side effects result' or similar. This 'because' they have conjured up is based on their faulty assumptions, not scientific evidence.

 

If you want a really simple and convincing illustration of what one could expect if all (skin based) sebaceous glands were to disappear, I've seen many top dermatologists point to young children, who produce very little sebum, and perhaps even more poignantly, to those with CAIS (Complete Androgen Insensitivity Syndrome), who produce little to no sebum for their entire lives. They do not age faster, their skin is not doomed to perpetual dryness or similar problems, their hair is normal - in fact, those with CAIS are known to often have particularly beautiful and thick hair, something they are able to maintain without sebum. Amazing though it may sound, if you could magically shut down sebum production in your body without affecting anything else, it does seem very likely you would suffer no setbacks, even in the long term.

 

The trouble is, most established methods out there targeting sebaceous glands (e.g. accutane) do have many unwanted effects. It would take a method that targeted the sebaceous glands in the skin and nothing else to become widely used for this to become more common knowledge.



#48 kissses

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Posted 18 May 2013 - 12:25 PM

Well, I'd rather look good my entire life.

I want to go to my 30 year high school reunion and laugh at all the bitches that look like leather handbags while my face is still practically wrinkle free thanks to my oily skin genes.

Oily skin is not a social death sentence. It just means you have to blot a few times a day. Big effing deal.


agreed, I have oily skin and since I found the right stuff to control it, I'd actually rather have it than chronically dry skin. Also my mom has the same skin type and looks gorgeous for pushing 50; everyone knows it. Maybe we can do with or without sebum, but i really don't mind it

#49 Binga

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Posted 18 May 2013 - 11:01 PM

Its not all about sebum. Immune function, genes play a greater role. Lot of people have oily skin but don't have acne. 



#50 Toro

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Posted 19 May 2013 - 07:26 AM

Its not all about sebum. Immune function, genes play a greater role. Lot of people have oily skin but don't have acne.

 
You're absolutely right. Acne has a multitude of causes and no two sufferers are exactly the same - that's why it's so hard to completely get on top of and eliminate. There are plenty of people with oily skin who don't have acne, as presumably they are relatively fortunate in other areas - genetics, hormones, immune system, lifestyle etc. Excessive sebum production on its own is one of many potential causes.
 
But in terms of how the acne is able to develop, whatever the underlying causes, in many ways it really is all about sebum. If you look at the biology of how acne develops, you'll realise that it couldn't really happen at all without an output of sebum. Whatever's causing the malfunction - and there are a great many factors, as you say - the sebaceous gland plays a central and essential role in the transmission of this disorder to the skin in the form of acne.
 
This point would be somewhat irrelevant if the glands served an important purpose, as even if you had a method of safely destroying them, it would carry obvious negative consequences - but given the abundant evidence that these glands have no important function in modern humans, and that the glands would not be missed even in the long term, this leaves the future open to some very promising acne treatments.

Edited by Toro, 19 May 2013 - 07:30 AM.