Updated: May 22, 2019
Which disorder affects almost 50% of our population and we know nothing about? It’s dandruff. It’s that flaky, powdery substance which behaves like a bad tenant who refuses to vacate the premises despite your many (failed) attempts. Two things have dawned on me during my research into this mystery:
Dandruff is much more than just dry, scaly scalp; and
We, including doctors, know nothing about how to get rid of it although there are many myths, propagated by the cosmetic industry, that help them sell a truck load of anti-dandruff shampoos to the gullible population.
Our scalp is a host to more than 50 species of bacteria, viruses and fungi
A recent study suggests that dandruff is associated with a disequilibrium in the bacterial-fungal ratio is the scalp.(1) A specific fungus, Malassezia (species), has been associated repeatedly among those having dandruff. However, it is a chicken and egg problem.(2) We do not know if the fungus leads to scaling or the clumps of dead cells in the scales provide a fertile ground for the fungus to proliferate. There is evidence that shows abundant scaling makes the usually harmless fungus pathogenic.(3) That’s the reason the anti-fungal shampoos work in the short term, but the long term once the fungus becomes resistant to it, dandruff returns.
So far, from the literature, we know that there are two possible triggers for dandruff:(4)
Host based: due to altered immunity of the host, the bacterial-fungal ratio alters and makes the host susceptible to scaly skin. During the initial stages, where there is no inflammation, scaly skin causes dandruff. Eventually, when the immune system becomes so broken down that it can end up in full blown dermatitis (requiring steroid treatment).
Environmental: Excessive combing, pollution, excessive shampooing or using alkaline shampoos, too much sun exposure are some established trigger factors.4
What do we do wrong??
We know the fungus might be the cause…so just eliminate it?? Wrong!
Malassazia is a commensal fungus (it lives off the lipids on our skin but causes no harm to the host under normal circumstances). When its population reduces, other more pathogenic fungi take over (like candida, cryptosporidium, and cladosporidium species) causing other problems. So basically antifungal treatment for dandruff is only replacing one (maybe harmless) problem with another (probably more severe) problem.(5)
There is a plethora of anti-dandruff shampoos in the market that are easily available for over the counter purchase and this is where everything goes wrong. Some contain anti-fungal agents (like ketoconazole) which seem to be effective only till such a time that the fungus becomes resistant to it. Then it’s back with a bang!
Another famous agent used is these shampoos is zinc pyrithione which causes DNA damage and energy crisis is normal skin cells thereby causing more skin-flaking and hair loss. Further, although human studies have not been done so far, there are genotoxic concerns about zinc salts in mice.(6)
Our normal scalp pH needs to be maintained between 2-4 (slightly acidic) which suppresses malassazia growth and keeps the microbiome in balance.(4)
However repeated shampooing, which we tend to do when we suffer from dandruff, makes the scalp more and more alkaline. This promotes the growth of the fungus and worsens the dandruff. Also, Malassezia loves fat (oil) and using hair-oils, oily conditioners, hair-lotions will only make things worse for you!
So what can you do??
Acidifying the scalp: Apple cider vinegar, lactic acid and citric acid (from lemon)are effective in acidifying the scalp. They, however, should not be used very frequently (once or twice a month at most) because they also promote dryness of the scalp. Using these acidic substances with cold pressed oils (which are mentioned later) has a better effect.
Essential oils: Some essential oils have exhibited properties that can be effective against dandruff and also excellent for dry scalp in general. Tea-tree oil,8 sage oil,9 lavender oil,10 peppermint oil, eucalyptus oil, Neem oil, lemongrass oil, Sandalwood oil.
Cold pressed oils: Avocado oil, sesame oil, almond oil and argon oil help for dry skin and since they do not have the oily, slick nature of coconut oils, they can be applied and left without rinsing.(11) But also remember that too much oil can also nourish the fungus.
Warm coconut oil with honey. Both have antibacterial and anti-inflammatory properties. Massage the mixture nicely through the scalp and let it rest for an hour. Follow by rinsing the hair with herbal shampoo (without soap or alkaline properties). Repeat it twice a week till the dandruff has been controlled.(11)
If dandruff is not the only problem but there are other associated skin conditions (dry skin, dermatitis, psoriasis etc.) or other major complaints, it’s better to see a holistic healer (homeopath, naturopath or ayurvedic) to get your system treated completely.
Findley K and Grice E. The Skin Microbiome: A focus on pathogens and their association with skin disease. PLOS pathogens 2014. 10(11): e1004436.
Saunders C et al. Malassezia fungi are specialized to live on skin and associated with dandruff, eczema and skin diseases. PLoS pathogens 2012. 8(6): e1002701.
Manuel F and Ranganathan S. A new postulate on two stages of dandruff: A clinical perspective. International journal of Trichology 2011. 3(1): 3-6.
Borda L and Wikramanayake T. Seborrheic dermatitis and dandruff: A comprehensive review. Journal of clinical investigative dermatology 2015. 3(2).
Clavaud C et al. Dandruff is associated with disequilibrium in the proportion of the major bacterial and fungal populations colonizing the scalp. PLOS One 2013. 8(3): e58203.
Lamore S et al. The topical antimicrobial zinc pyrithione is a heat shock response inducer that causes DNA damage and PARP-dependent energy crisis in human skin cells. Cell stress and chaperones 2010. 15: 309-322.
Vijaykumar R et al. Characterization of Malassezia Furfur and its control by using plant extracts. Indian Journal of Dermatology 2006. 51(2): 145-148.
Satchell AC et al. Treatment of dandruff with 5% tea tree oil shampoo. Journal of the American Academy of Dermatology, 2002. 47(6):852-855.
Reuter J et al. Sage extract rich in phenolic diterpenes inhibits ultraviolet-induced erythema in vivo. Planta Medicine 2007. 73(11):1190-1.
Sienkiewicz M. Antibacterial activity of thyme and lavender essential oils. Med Chemistry 2011. 7(6):674-89.