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Aiona's Minute Medical Text of Skin Biochemistry

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I had a friend who passed away about 11 years ago. The anniversary of her death will be this August 13th. Her friendship really affected my life in so many ways. I'll always be indebted to her for the advice, wisdom, and jokes that she shared with me.

I remember we were discussing something once, computer programming, I believe. She explained why something I was doing wasn't working. I vented my frustration, and after a pause, she said, "Ignorance."

I was like, HUH?

And then she smiled and said, ". . . is curable." I wanted to hit her.

But she was right. There is always something to be learned.

I am galvanized tonight because of sherapop's little blog posts. I read all three of them, and post links to them below.

The Myth of Skin Chemistry Myth. Introduction
The Myth of Skin Chemistry Myth. Proof 1
The Myth of Skin Chemistry Myth. Proof 2.
The Myth of Skin Chemistry Myth. Proof 3.

I read all three of them, sherapop, because this subject interests me greatly. I am convinced there are explainable physiologic reasons for why people prefer certain scents, whether it be because neural networks of pleasurable associations were created due to life events (much as a motor vehicle accident can leave lasting impressions both psychologically and physically) or because of scent receptors that differ due to small DNA mutations or because of physical epithelial differences (also due to DNA mutations). The latter subject was the main topic of sherapop's posts.

Like you, I too believe that people have individual skin chemistries. I will give three instances also, but related more to pathological medical conditions.

I. Cystic Fibrosis

(This is basically a cut-and-paste of my comment on sherapop's web log, as I wasn't about to retype this all at 1:44 AM.)

Medical doctors have known for about half a century that there is a difference in skin chemistry. The biggest example is cystic fibrosis -- a defect in the chloride channel that is present in epithelium, not only of the skin, but also the gut, the pancreas, and the lungs. How does one diagnose cystic fibrosis? Well, before the creation of (relatively) cheap polymerase chain reaction machines, we diagnosed it with. . . MEASURING SWEAT CHLORIDE. There is a statistically significant difference between those who have a defective chloride channel, and those who do not. And it correlates well enough with PCR evidence, that it is still the gold standard for diagnosis. Why? Because we still do not know all the mutations of the chloride channel, and without the exact DNA sequence of a particular mutation, one cannot perform PCR to look for it. So currently, PCR is only used to verify known common mutations of the chloride channel.

ANYWAY. That is one pathologic difference in skin that is commonly measured in pediatric hospitals around the world.


And we only look for it because it causes problems for those who have it.

There are gazillions of possible mutations in not just chloride channels, but sodium channels, potassium channels, bicarbonate exchange, etc. We don't even know them all.

Just because we don't measure other channels, doesn't not mean that those differences do not exist.

If you suspect that someone you know has cystic fibrosis, you might wanna read the U.S. National Institutes of Health website about it at http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001167/

II. Selective IgA Deficiency

I strongly encourage *everyone* to take an immunology course. At your local community college or university. Even online! (Surely, the University of Phoenix has an online course, although I am loathe to do a search to find out.)

Unless you have a immunodeficiency disorder, you are making antibodies. Right now. And everyone should be making 5 general types of antibodies. Immunoglobulin M (aka IgM), Immunoglobulin G (aka IgG), IgD, IgE, and IgA.

Each type of antibody has its own function. I'm not gonna list all their freakin' functions, because it is now 1:47 AM. But suffice it to say that IgA is secreted in epithelium (i.e. skin. . . the skin of your body, the skin of your gut, the skin of your lungs)

IgA is an antibody that is specialized to protect against any bug that wants to invade your skin.

How do we know that? Well, there are certain people who lack the ability to make IgA. And. . . the common problem that they share (and the reason they usually wind up getting diagnosed is) because they get frequent skin infections. Also pneumonia, because IgA is secreted in the "skin" of the lungs, and without it, people are less able to fight off lung pathogens.

If people are able to mobilize immune forces in skin, that means enzymatic reactions take place in the skin. Enzymes modify chemical structure. Perfumes are chemicals. Enzymes can modify perfumes.

There are other types of immunodeficiencies which manifest itself in skin. 'Not gonna list them all.

For more information about Selective IgA deficiency, I recommend the U.S. National Institute of Health's website: http://www.nlm.nih.gov/medlineplus/ency/article/001476.htm

III. Skin Changes of Pregnancy

Physiologic changes due to pregnancy is another topic which is near and dear to my heart. WHY? Because I've recently had to get rid of all my previous favorite perfumes because my preferences have undergone an irritating transformation. Irritating to my pocketbook. That's why it hurts so much. I've inherited the stingy gene.

I am convinced there are physiologic changes that one undergoes in pregnancy that affect not only one's reaction to smells, but possibly also changes in one's skin. Everyone knows that immune responses are blunted during pregnancy. It would follow that IgA secretion in skin may be affected. I wish someone would do a perfume related study on it, but there are more pressing medical issues to address, I know, and grant research resources are limited these days.

There are numerous skin conditions which are only found during pregnancy.

Linea nigra is one.
Melasma of pregnancy is another.
But another pathologic condition is. . . Pruritic Urticarial Papules and Plaques of Pregnancy (i.e. PUPPP) (Try saying that 5 times really fast.)

What do all of these changes have in common? They are likely induced by changes in hormones. Linea nigra and melasma are correlated with hormones of pregnancy. The hypothalamus and pituitary are hotbeds of hormones, smack dab near the limbic system.

There are some complications of delivery that can cause irreversible damage to one's hormone production. Sheehan syndrome is one example.

Why am I going on and on about hormones? Well, hormones affect the immune system. One of the common treatments for PUPPP is steroids. If steroids can affect the immune system, they can also cause changes in the skin.

IV. Conclusion

It is my belief that people have different skin chemistries. Everyone can draw their own conclusions -- including Luca Turin.

It is now 2:29 AM. I am going to sleep. Thank you and goodnight.


  1. Nostalgie's Avatar
    Fascinating! Thanks, Aiona!
  2. ECaruthers's Avatar
    Thanks, for quite a lot of new information,Aiona. I also believe that skin temperature differences are likely to effect how fast 'fume components evaporate from the skin. Skin chemistry might add some extra fragrances to the mix. Chemicals on the skin's surface might even react with and destroy some components so they never make it to your nose. I don't know any studies that show whether these are large or tiny effects or, if they are large, whether they are important only in pathologies or are a large part of our different reactions to the same scents.

    But I do have a test to suggest. Can you go through a store, test a bunch of scents on paper, pick one you like, and buy it without applying it to your own skin? This must work well enough for enough people - after all the stores provide the test strips. But some people say, "I don't care what it smells like on paper; I don't care what it smells like on someone else; I only care how it smells on me." I think their skin chemistry must be different.

    As a variation on this test, try spraying your old favorites on paper - an unscented kitchen paper towel will do. If they smell wonderful, maybe it is just your skin that's changed. But if you don't like them any better on paper than on your skin, then maybe it's something in your nose or brain that has changed.
  3. sherapop's Avatar
    Great examples, Aiona!

  4. Chicagoista's Avatar
    Absolutely wonderful! I salute you for going so in-depth on this subject.
  5. Redneck Perfumisto's Avatar

    I totally agree - you can overwhelm skin with enough fragrance, and measure things early enough in development, that everybody's skin is the same. But when you count not only the genetic and consequent biochemical variations in the skin, but also the resident flora and fauna (in turn highly dependent on a myriad of factors, including chemical history and moisture and....and....), it's clear that no skin is the same by the time you get into the heart of a fragrance, and especially by the time you're down to the base.

    It's a complex equation, and provided that you don't skew things into sameness by tilting the game, differences are easily observed, if not always easily explained.

    I'm a believer in observational science - be those observations the patterns that Turin sees, or yourself. Nobody is in a better position to see the effects of pregnancy on scent than the scientist herself!
  6. Aiona's Avatar
    Y'know, ECaruthers, when I did the Blind Sniff in March 2011, veteran sniffers encouraged us to spritz on paper, as that tends to make top notes last longer versus on skin. It did seem to do that.
  7. Primrose's Avatar
    Thank you for sharing.

    Metabolic disorders like diabetes will cause a person to have a sweet or vinegar scent to the skin.


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