16 replies to this topic

[bio_nerd]

Hi i found this study on proposed synthetic human sebum (skins natural moisture)
very interesting.

The proposed ingredients were:

17% fatty acid
44.7% triglyceride
25% wax monoester (jojoba oil)
12.4% squalene

Sebum is basically the ultimate moisturizer for human skin, nothing could be better than it considering we produce it ourselves naturally.

LINK:

http://www.ncbi.nlm.nih.gov/pubmed/19134124

[joris]

Dont some people think sebum contributes to acne?

Edited by joris, 03 October 2010 - 02:43 PM.

[bryan]

Hi i found this study on proposed synthetic human sebum (skins natural moisture)
very interesting.

You consider a fatty substance produced to some extent in the skin to be its natural "moisture"? Seriously?

Sebum is basically the ultimate moisturizer for human skin, nothing could be better than it considering we produce it ourselves naturally.

Sebum has no significant effect at all as a moisturizer for our skin. I've cited the medical evidence numerous times in the past.

[bio_nerd]

You may be right, perhaps it is for moisturizing the hair when we DID have hair on our
faces but evolved to lose it.

Accutane is said to slow or stop sebum and look what happens to their skin and hair, it dries out
severely.

I'm not willing to get in an argument over opinions, fact is nobody knows what sebum is really for.

[bryan]

Accutane is said to slow or stop sebum and look what happens to their skin and hair, it dries out
severely.

You're making the same logical error that so many other people have made: you're assuming that there's a connection between the lack of sebum and the dry skin. But there isn't! As I've pointed out in the past, pre-pubertal children produce even less sebum than older teenagers and adults taking Accutane, but they obviously don't have problems with dry skin.

I'm not willing to get in an argument over opinions, fact is nobody knows what sebum is really for.

You're willing to make outrageous claims about how sebum is supposedly the "ultimate moisturizer for human skin", but you're not willing to argue about it?

[03GT]

Sebum is not a moisturizer in that it does not directly contribute to the water content within cells. However, sebum is a nonpolar substance and when it saturates the face it does act as an anatomical barrier to keep moisture locked into the cells. So it has a more indirect effect on moisture. I think maybe that's what the op was getting at.

And sebum is directly related to acne. It is the energy source for p. Acnes. What eludes scientists is that everyone secretes sebum but not everyone gets acne so perhaps acne sufferers have 'tackier' sebum. A therapeutic that did increase the fluidity could possibly deter the formation of acne it is unlikely, IMHO, that this could be done using an exogenous source such as a topical since sebum is secreted near the base of a follicle therefore pushing any topical out of the way.

Edited by 03GT, 09 October 2010 - 03:31 PM.

[bryan]

Sebum is not a moisturizer in that it does not directly contribute to the water content within cells. However, sebum is a nonpolar substance and when it saturates the face it does act as an anatomical barrier to keep moisture locked into the cells. So it has a more indirect effect on moisture. I think maybe that's what the op was getting at.

I've previously posted the full details of the experiment done years ago by Kligman which showed that to get even a modest measurable increase in the moisture content of skin, it was necessary to apply literally 10 times the amount of sebum that normally occurs on the oiliest part of human anatomy (like on the face). That clearly shows that normal and typical amounts of sebum, even on really oily areas of the skin, have no significant effect as a moisturizer.

[bio_nerd]

So, why DOES accutane dry out the skin and hair then?

forgive me for using logic but,

accutane stops sebum > skin dries out > therefore i must come to the conclusion
that sebum must have SOME connection SOMEWHERE in the process of keeping skin
moist.

Could it have anything to do with an increase in facial hair? children do not have facial hair so
perhaps they don't need sebum as much.

Edited by bio_nerd, 09 October 2010 - 05:14 PM.

[bryan]

So, why DOES accutane dry out the skin and hair then?

forgive me for using logic but,

accutane stops sebum > skin dries out > therefore i must come to the conclusion
that sebum must have SOME connection SOMEWHERE in the process of keeping skin
moist.

Oh, I don't really know all the specific reasons for why Accutane dries out the skin, and I don't know if even doctors and scientists know that yet, either. But a very well-informed poster on this forum was discussing several months ago the issue of all the things that Accutane does to the body, and he stressed that the drug has an incredible shotgun-like effect on a huge array of genes in the body. It wouldn't surprse me at all if even the medical profession doesn't (yet) know why it can have such a drying effect on the skin.

In the meantime, until the experts can actually answer that question scientifically, don't make the silly and unwarranted assumption that so many other people have made on this site by jumping to the conclusion that sebum plays a role in maintaining moisture in skin! As Kligman pointed out very persuasively many years ago, prepubertal children produce almost no sebum at all, yet have no difficulty maintaining normal and attractive skin, and normal levels of moisture in the skin. Furthermore, an actual experiment by Kligman (see my reply to "O3GT" just above) showed that really _huge_ amounts of sebum had to be applied to skin, before even the BEGINNINGS of a beneficial effect on moisture maintenance could be observed.

Edited by bryan, 09 October 2010 - 06:39 PM.

[03GT]

So, why DOES accutane dry out the skin and hair then?

forgive me for using logic but,

accutane stops sebum > skin dries out > therefore i must come to the conclusion
that sebum must have SOME connection SOMEWHERE in the process of keeping skin
moist.

Could it have anything to do with an increase in facial hair? children do not have facial hair so
perhaps they don't need sebum as much.

Science has well-established definitions for certain terms. Depending on who you ask, some might say a moisturizer is the same as a hydrator in that it donates water molecules leading to the hydration of a substance (which sebum does not since it is a lipid). Others may say it's simply a substance that reduces the loss water from a substance by either donating water molecules or reducing evaporation (in this case sebum does, since it reduces evaporation). Don't get caught up in the terminology. Your statements are correct in that the reduction of sebum caused by accutane leads to dry skin. Sebum is analogous to the waxy covering that surrounds leaves in plants, called the cuticle. Without it, the leaf would dry out.

[bryan]

Your statements are correct in that the reduction of sebum caused by accutane leads to dry skin.

Do all children suffer from dry skin?

[bryan]

Journal of Investigative Dermatology. 1987 Mar;88(3 Suppl):2s-6s.
"Skin lipids: an update"
Downing DT, Stewart ME, Wertz PW, Colton SW, Abraham W, Strauss JS.

(excerpt from this study follows below, including the references...)

Sebum and Dry Skin "...skin can be healthy and have charming cosmetic properties in the virtual absence of sebum." (14)

Kligman drew attention to prepubertal children, who produce almost no sebum, to support his thesis that skin does not depend upon sebum for maintaining its barrier to water loss: "...there can be no doubt of the insignificance of sebum as a waterproofing material." (14) Our recent studies at the other end of the human age spectrum have supported this conviction. In a survey of sebum secretion rates and the incidence of dry skin among subjects aged 65 to 97, no correlation was found between sebaceous gland activity and the presence or severity of dry skin (34). Kligman recognized that sebum could mask the scaliness of dry skin without producing any actual change in the condition: "Sebum, like any oil, has some emollient or smoothing effect when a sufficient quantity is rubbed into dry, scaling skin." (14) In spite of the clear inference to be drawn from the cutaneous characteristics of children and the experimental data obtained from the elderly, it remains difficult to dispel the myth that low sebum secretion rates cause dry skin. It is a rare individual who realizes that "dry" is not the obverse of "oily".

(14) Kligman AM: The uses of sebum. Br J Dermatol 75: 307-319, 1963

(34) Frantz RA, Kinney CK, Downing DT: A study of skin dryness in the elderly. Nursing Res 35: 98-100, 1986.

[bio_nerd]

(21) Kligman regards the human sebaceous glands as 'living fossils' that lost their usefulness to our species as we lost our fur.(21)

Bryan, the quote above was taken from one of your posts here:

http://www.acne.org/messageboard/Sebum-moi...in-t225392.html

So there is a connection then, kids don't produce sebum because they don't need it,
they rely on their sweat glands to maintain moisture.

In puberty, we develop facial hair, which results in the production of sebum.
but we have lost our need for sebum through evolution.

I understand that a lack of oil does not necessarily mean dry skin, that is how kids
can get away with not having sebum.

My original statement then, was not entirely false - sebum does play a role in moisturizing
and protecting facial hairs. Just because kids don't have it, doesn't nullify it's role in adults.

Am i on the right track here?

I also found this:

Neal Schultz, M.D. on October 29, 2009 at 4:35pm

@Adam Goldstein: Thank you for providing this conversation with another view point. I however, respectfully disagree with your stance, even though as you point out, Dr. Kligman would agree with you. While certainly a pioneer in the field of acne and very prolific in his research, like many other notable researchers he had views, did research, and came to conclusions that were not all embraced by everyone in the professional community. Many of my peers (whether professors of dermatology at university medical schools or practicing clinical dermatologists who are "on the front lines" taking care of most of the patients) would disagree with Dr. Kligman in his conclusion that sebum (i.e., oil) is not important in reducing TEWL and maintaining the skin's hydration; we believe that it is, and I'll explain why. Since DermTV is about helping people with clinical real life skin issues, I'd like to cite the common condition of "senile pruritus" (i.e., itching skin in older people) as clinical evidence of the all important role of skin sebum in maintaining skin hydration directly by reducing TEWL. As everyone ages (and especially past the age of approximately sixty), their oil glands produce less oil and ultimately (in most cases) become dysfunctional and make none. This loss of sebum production is the direct and proximate cause of the increased drying and relative dehydration of the epidermis that causes their intolerable itching (i.e., senile pruritus). This is the most direct example of why to me and my peers, sebum does in fact help the skin maintain surface moisture and hydration, as I mentioned in my comment above.

The above taken from here:

http://www.dermtv.com/understanding-your-o...water-skin-type

You just can't ignore the fact that accutane slows sebum down and as a result, dry skin. I mean
come on there has to be a connection there?

Edited by bio_nerd, 13 October 2010 - 01:06 AM.

[bryan]

So there is a connection then, kids don't produce sebum because they don't need it,
they rely on their sweat glands to maintain moisture.

LOL! Is THAT the only way you can think of to try to explain why children do just fine without any sebum? Why have you ignored the other part about the study they did with elderly people, which got the same results (differences in sebum production had no correlation to dry skin)?

In puberty, we develop facial hair, which results in the production of sebum.
but we have lost our need for sebum through evolution.

Facial hair causes sebum? Really? How do you explain the very heavy occurrences of sebum on parts of the body that have no hair at all, like the nose and forehead?

I understand that a lack of oil does not necessarily mean dry skin, that is how kids
can get away with not having sebum.

My original statement then, was not entirely false - sebum does play a role in moisturizing
and protecting facial hairs. Just because kids don't have it, doesn't nullify it's role in adults.

Am i on the right track here?

I don't think so. I would completely ignore this thing about sebum and moisturization. There's nothing to it at all. It's a dead issue.

I also found this:

Neal Schultz, M.D. on October 29, 2009 at 4:35pm

@Adam Goldstein: Thank you for providing this conversation with another view point. I however, respectfully disagree with your stance, even though as you point out, Dr. Kligman would agree with you. While certainly a pioneer in the field of acne and very prolific in his research, like many other notable researchers he had views, did research, and came to conclusions that were not all embraced by everyone in the professional community. Many of my peers (whether professors of dermatology at university medical schools or practicing clinical dermatologists who are "on the front lines" taking care of most of the patients) would disagree with Dr. Kligman in his conclusion that sebum (i.e., oil) is not important in reducing TEWL and maintaining the skin's hydration; we believe that it is, and I'll explain why. Since DermTV is about helping people with clinical real life skin issues, I'd like to cite the common condition of "senile pruritus" (i.e., itching skin in older people) as clinical evidence of the all important role of skin sebum in maintaining skin hydration directly by reducing TEWL. As everyone ages (and especially past the age of approximately sixty), their oil glands produce less oil and ultimately (in most cases) become dysfunctional and make none. This loss of sebum production is the direct and proximate cause of the increased drying and relative dehydration of the epidermis that causes their intolerable itching (i.e., senile pruritus). This is the most direct example of why to me and my peers, sebum does in fact help the skin maintain surface moisture and hydration, as I mentioned in my comment above.

Oh yes, I've already read that passage a long time ago, when another reader first posted it. Unfortunately, Dr. Schultz doesn't explain the results of the other dermatologists I cited, who detailed their experimantal results among the elderly patients, and found no correlation between sebum and skin dryness in those patients. Frankly, I trust those other dermatologists (and especially Dr. Kligman, who is a LEGEND in the field of dermatology!) a lot more than Dr. Schultz, who just seems be making the same simple-minded assumptions about sebum that are made so often by lay people.

You just can't ignore the fact that accutane slows sebum down and as a result, dry skin. I mean
come on there has to be a connection there?

Nope, I don't think there's any connection at all. There have been articles posted here in the past by knowledgeable readers which have described the PROFOUND changes made by Accutane on the chemistry of the skin. It's those changes it makes on the skin which affects its ability to hold moisture, not just the effect on sebum production, which is completely superficial by comparison.

You've made only a laughable effort to explain why children do just fine without sebum at all, saying that for some strange, unexplained reason they simply don't "need" sebum for that purpose; you've ignored the study by the dermatologists that found no correlation between sebum production and skin dryness in the elderly; you've ignored the other experiment done by Kligman which found that HUGE amounts of sebum (more than 10x the large amount found in oily areas like the face) had to be applied to human skin, before it had any measurable effect at all on water retention; you've ignored the fact that fully-grown adults with CAIS (Complete Androgen Insensitivity Syndrome) aren't known for having problems with dry skin, despite the fact that they have the same almost non-existent sebum production as young children. There's a lot here that you haven't explained or even commented on, isn't there?

[bluedoganchorite]

You ignored the one thing that comes from Kligman himself, taken from one of your OWN posts.

(21) Kligman regards the human sebaceous glands as 'living fossils' that lost their usefulness to our species as we lost our fur.(21)

Bryan, the quote above was taken from one of your posts here:

CODE

http://www.acne.org/messageboard/p1/messageboard/Sebum-moisturizes-skin-t225392.html

For god's sake, you even bolded it!.

Yet you say it's laughable that i would make a connection to facial hair and sebum when Kligman
the man you adore so much thinks the same!

Kligman himself says he believes they may have had a purpose when we had fur on our face. Why did you attack everything else i said, but fail to acknowledge this?

No, instead you choose to attack me personally, calling me "laughable". Thanks alot man, that's
the last time i try to have i normal conversation with ignorant stuck-up people like you i swear to god.

Obviously you have already made up your damn mind so why even bother.

I'm sure you will probably reply to this and ignore kligman's quote yet again because you have
nothing better to do then just put down what other people say.

Edited by bluedoganchorite, 13 October 2010 - 11:10 PM.

[bionerd]

You didn't acknowledge this statement from Kligman. Taken, as i said - from one of your
own posts, it was even bolded

(21) Kligman regards the human sebaceous glands as 'living fossils' that lost their usefulness to our species as we lost our fur.(21)

You said i was wrong about a connection between facial hair/facial fur and sebum/sebaceous glands.
sebaceous glands must have been of some use to the fur judging by Kligman's wording.

Yet, Kligman himself believes there is a connection , so am i to assume you disagree with Kligman?
The man who's research you are basing your entire argument on?

[bryan]

You didn't acknowledge this statement from Kligman. Taken, as i said - from one of your
own posts, it was even bolded

(21) Kligman regards the human sebaceous glands as 'living fossils' that lost their usefulness to our species as we lost our fur.(21)

I've posted a great many excerpts and quotes from Kligman over the years, including that one above about sebaceous glands being "living fossils". If I took the time to acknowledge EVERYTHING he's ever said about them, I'd be here all night!

You said i was wrong about a connection between facial hair/facial fur and sebum/sebaceous glands. sebaceous glands must have been of some use to the fur judging by Kligman's wording.

I think you're completely wrong when you claimed that facial hair currently causes the production of sebum. As I pointed out to you before, that's patently false.

Yet, Kligman himself believes there is a connection , so am i to assume you disagree with Kligman? The man who's research you are basing your entire argument on?

In the excerpt that you quoted before that included the statements from Kligman, the other dermatologists were careful to point out that sebum _may_ have served some kind of useful purpose a long long time ago, when we had a lot more body fur than we do now. But as we lost that body fur, we lost the need for sebum, which is now a "living fossil". I personally have no idea if those dermatologists are absolutely correct about what they said, but their basic idea seems very reasonable to me.