Dandruff and the Creepy Crawlies!

I have recently read several articles which I found fascinating and which explained to me the current scientific thoughts on dandruff. First remember that our scalp (and skin in general) is teeming with bacteria and fungi!! This is actually very natural and normal. An old estimate was 1 million of these little things per square centimentre! If you have dandruff the number went up a little bit to 1.2 million. (J. Soc. Cosmet. Chem., pgs 111-139, 1976). Therefore having the creepy crawlies is nothing to cause alarm.

Shampoo manufacturers in particular Procter and Gamble, have actually done a great job of find out what causes dandruff. Dandruff is now thought to be linked to three factors

1. Sebum - the natural oil produced by the skin and the fungus food!
2. A specific fungus - Malassezia globosa- which consumes certain oils found in sebum leading to production of an acid (oleic acid) that disrupts the cells of the scalp causing them to slough off
3. Individual susceptibility - meaning that not everyone will produce sebum in the quantity needed to get the fungus to multiply and not everyone's scalp will react the same way to the presence of oleic acid. Some will get dandruff others won't. 50% of people get dandruff and 50% don't.

The research was fascinating. Scientists have even gone the extra mile to decode the genome of this yeast (meaning find out the DNA sequence to see what kind of proteins it makes) in the hope of developing more effective ways to kill/control it.

So there you have it, the definitive answer to the cause of dandruff! (Sources : J Cosmet Sci, pg 81-2, 2006; J Investig Dermatol Symp Proc, pgs 15-9, 2007 and PNAS, vol. 104 no. 47 18730-18735 , 2007. ). I would add that many of the oils (including my beloved coconut oil) that naturals will use actually contain triglycerides and even oleic acid. If you are suffering from dandruff, cutting back on these oils may be useful.

I have received many questions about itchy scalp and dandruff. I sort of drew my own line in the sand because although these are hair related issues, they really do fall more into the medical field. I would really encourage anyone who has issues with dandruff to see a dermatologist especially if the dandruff is not resolved by using an over the counter specialist dandruff shampoo. These shampoos are very effective against dandruff so you may not have dandruff at all if they don't work. It could be eczema or another skin disorder or it could be severe dandruff - whichever way, see your doctor.

The picture is an unrelated image of E.Coli - nothing to do with the scalp, just symbolic and because I like their sausage shape!

Image Credit


  1. Since stopping harsh shampoos and using coconut oil, my dandruff is a thing of the past!

  2. I 'm supose to be washing my hair twice a week witch is a nightmare for a kinky haired personne so i finally found a methode(i suffer from seborrhea ). I wash once a week with head and shoulder and in the middle of the week, i put jojoba oil mixed with tee trea on my scalp and let it in till the next shampoo. Jojoba is not an oil. It is a wax so the fungus can not change it into oleic acid. For the tee trea, i 've red that it has to be at least 5% of the mixture to be effective. If not, it can even worsen the situation on the long run cuz the fungus get used to it ( that makes me even worry about so called product with tee trea in it). I never put a rinse out conditioner after a shampoo cuz if it touches my scalp i believe it do not completely rinse out and that will mean a moisturized scalp witch fungus love. I don't know for malassezia though do you think i'm over doing it for the rinse out? I put a leave in instead but i will like to condition with a rinse out. I also never oil my scalp for the reasons you explained.
    Good post as always.

  3. Flakes don't always equal dandruff or a medical condition. I found that my flakes were due to a coconut allergy. Who knew coconut was in 99% of shampoos?

    Make sure to read the ingredient list and know the alternate names for ingredients that you're allergic to. You may think that you're doing something good for your hair/scalp by using certain products, but you could be doing harm if you don't know what you are putting on your hair.

  4. hmMm...i haven't had dandruff since i stopped getting a relaxer. i've been using coconut oil for about six weeks now. so far, no adverse effects. i have noticed that my scalp stays cleaner longer since beginning to use bentonite clay once a month, so perhaps the clay is mitigating any problems.

  5. Just like Keisha i have had dandruff since i stopped getting relaxers.

    Question though JC does bentonite clay really pull toxins from the hair and skin?

  6. I recognized it as E. Coli and I thought you found a connection between E.coli and hair and I was about to get REALLY nervous.

    So THANKS JC for my almost hair panic! :)

    Did your paper say have far there were decoding it? That's so cool!

  7. I always had this weird flaking area right on my hairline in front. I used Nizoral shampoo and it helped a bit but now that I wash weekly and use better quality products its gone. I still shampoo with nizoral once a month to be safe. I shampoo just my scalp.

    1. I suffer from this same exact problem. Did you ever see a dermatologist for a diagnosis or did the Nizoral keep it at bay? I use Neutrogena T-Sal for mine. But, I still will get reactions to different styling products but cannot figure out what's causing the reaction.

  8. as far as i can understand, there is some discrepancy between this post and the other one on the same subject,JC
    here you say:
    in other article you axplain it differently:

    "A specific fungus - Malassezia globosa- which consumes certain oils found in sebum leading to production of an acid (oleic acid) that disrupts the cells of the scalp causing them to slough off"

    "Sebum: The fungus Malassezia uniquely prefers one specific fat in sebum known as oleic acid. By specifically choosing to consume this fat above all others in sebum, the composition of sebum is altered . This alteration is then thought to lead to the cells on the scalp losing their adhesiveness and flaking off."

    for me only one of the explanations can be correct,probably the second one. can you correct it please JC?

    1. Sorry for the confusion, I can totally see how it looks contradictory but it is not. Malassezia liberates the oleic acid from the sebum. Sebum is composed of several fatty acids, cholesterol, squalane etc so it is more complex than just oleic acid. In dandruff, the artificially high levels of free oleic acid on the surface of the skin cause the skin to slough off. Malassezia is creating this situation for people who are susceptible to dandruff because it wants to consume the oleic acid.

      I hope this is a little clearer as to why the oleic acid is produced and consumed at the same time.


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