The real reason you get dandruff

It’s more than just an embarrassing annoyance – for some people, dandruff, and its associated conditions, can be downright uncomfortable. And from itchy scalp to dryness to flaking – it’s something many of us deal with: about 50 per cent of the global population experiences it in some form.

“What people or how people may articulate that in terms of their experience may be very different. They may or may not say they have flaking, they may or may not say they have dandruff – they may just say they have an itch,” explains Dr. Rolanda J. Wilkerson, Head & Shoulders Principal Scientist. “Whereas in fact only about 10 per cent of the population actually suffers from itch proper.

But what exactly causes it?

According to Wilkerson, there’s two major components at play.

The first is a scalp fungus called malassezia furfur. As gross as it sounds, everyone has it. However, Wilkerson says that at puberty, those who are more genetically susceptible to responding to the presence of that fungus on the scalp will begin to experience those telltale symptoms of dandruff – flaking, itch, dryness and irritation.

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You also have to have the presence of sebum, a natural oil that comes from the sebacious glands on our scalp. Wilkerson explains that different people will produce sebum at different rates and during different parts of their lifetime, but everyone has these oils.

“The malassezia feeds off the sebum, and as a result, they produce a toxic byproduct or waste that they put down on the scalp,” she says. “The scalp of the person who is more genetically susceptible to responding to the presence of that byproduct, will then respond and their skin will say ‘Wait a minute, something is there that should not be there, I need to protect myself.’ And so then as a result, those skin cells begin to actually speed up.”

That process is called hyperproliferation, which means more skin cells on the scalp than usual.

“That process happens from about seven to 21 days. The normal rate of cellular turnover is about 28 days,” Wikerson explains. “So as a result of the skin cells building up on the scalp, we then can visibly see that as flaking. That process also introduces irritation, and irritation will result in itch. The body also produces something called histamine, a signal of itch. The product of histamines help the body by saying ‘I need to scratch, there’s something going on,’ and then as a result there’s a repetitive cycle of itching, flaking, dryness, if the person does not use an effective anti-dandruff product.”

So who’s most likely to have dandruff?

First of all, Wilkerson notes that it typically starts during puberty when people begin to produce sebum (similar to getting acne.) Both men and women experience it at the same rate, as well as different populations and ethnicities. She says that it’s more about habits that drive how any given person may articulate their experiences. For example, a person who washes their hair less may say they have dandruff more frequently than someone with a higher wash frequency, who may not be fully realizing the flaking. Same when it comes to time of year – sometimes people will say they have dandruff only in the winter, but it may be because they’re wearing darker clothes, which makes the flaking more visible.

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According to new Head & Shoulders research – external factors can also be at play. “Those with a dandruff prone scalp can actually experience oxidative stress, like with UV damage,” Wilkerson says. “The scalp is experiencing oxidative stress from the presence of the fungus. As a result, the dandruff condition can be worsened through external factors, like malassezia, and other sources of stress like the environment, pollution, heat can impact and make that feel worse.”

OK, so now you know what causes dandruff – but how do anti-dandruff shampoos combat those annoying symptoms? That’s all thanks to a certain ingredient called zinc pyrithione, which is found in all anti-dandruff shampoos. But turns out, they’re not all created equally. In February, Head & Shoulders published a paper in the Journal of Drugs in Dermatology that proved why the brand has been on top of the dandruff-control game for years.

“We’ve turbocharged it with adding zinc into the formula, which essentially keeps the ZPT in our products stabilized when used on the scalp. ZPT is a molecular structure – we’ve designed it so we get maximum deposition onto the scalp that actually targets the source of dandruff, the fungus that resides on the scalp as well as the hair follicle,” says Wilkerson. “The fungus lives a lot in those crevices, and if you don’t have an AD shampoo that has a particle size of the ZPT small enough to actually get you where the malassezia is residing in the hair follicle, it will not be as effective as it needs to be. With our added zinc, we’ve strengthened the ability of the ZPT to remain bio-available or bio-active longer.”

Turns out, there’s a lot more going on when it comes to your scalp than you might think.

Do you suffer from dandruff? Let us know by tweeting @YahooStyleCA.