By THÉRÈSE MARGOLIS    

We all trust our hairstylists implicitly, or else we wouldn’t be going to them.

If they tell us that a certain product will strengthen our locks and give us extra shine, we immediately race off to the nearest department store to purchase a lifetime supply (just in case they might run out).

If they tell us we need a trim, we surrender our tresses to the whims of their scissors.

And if they tell us that putting birth control pills in our shampoo will make our hair grow faster…

Well, maybe we wouldn’t all fall for that line, but styling specialist Ruben Plata, owner and director of Rubén Plata Studio in Colonia Cuauhtémoc, says a lot of Mexican women do.

“It’s one of the most common myths that hairdressers here pass on to their clients,” he said in a recent interview, explaining that many women believe the hormones in the pills actually stimulate the hair follicles and speed up hair’s production process.

“In fact, there are a whole series of misguided beliefs about hair care that are passed from beautician to client, and a lot of women follow this misguided advice.”

So what are the most common bits of misinformation your hairdresser might tell you?

We asked Plata, and he offered the following list of the six most common myths about hair.

Myth 1: If you cut your hair often, it will grow faster.

“This is nonsense,” Plata said. “Cutting your hair will only make it shorter.”

Plata went on to explain that the hair that we see on our heads is already dead, or more precisely, the keratin protein remains of dead hair. The only living hair we have is at the follicle, which is inside our scalps.

Since there are no nerves, blood vessels or any other means of communicating hair ends to the scalp, your follicles have absolutely no way of knowing if you have trimmed your bangs, adopted a layered look or gotten a Mohawk.

“Most hair grows at a rate of about one centimeter per month, regardless of whether you cut it or not,” Plata said.

Folktales about cutting your hair on a full moon or at a certain time of day to increase the growth rate are equally unfounded, he said.

Myth 2: If you pull a gray hair out, two will grow back in its place.

“Again, this is totally irrational,” Plata said. “If you pull out a gray hair, a gray hair will grow back, not two gray hairs, just one.”

Gray hair is basically caused by the loss of pigmentation, an inevitable consequence of aging.

Your genes are to blame for what age this happens to you, and no matter how much you want to stop it, once your follicles stop producing pigment, all your subsequent hair will grow back gray (thank God for hair color).

Myth 3: If you use good hair coloring and permanent solutions, they won’t damage your hair.

“Any chemical processing will harm your hair,” Plata said. “The chemicals strip the hair shaft and make it vulnerable to splits. The secret is to try to use as mild a processing treatment as possible.”

For light color coverage, there are a lot of ammonia-free products on the market such as Revlon Colorsilk with Buttercream or low-ammonia tints such as Garnier’s Olia, which uses the power of oil to infuse color.

But if you have a lot of grays (see myth two above), you will need a stronger product, and that means heavy chemicals.

L’Oréal’s Age Perfect is especially formulated for hard-to-color hair.

“Obviously, you want to choose a brand with a reliable reputation and to try to avoid over-processing.”

Plata also warned that permanent and straightening treatments can leave hair weak and fragile. The same applies to heat exposure from driers or electric curlers.

Myth 4: Applying mayonnaise masques to your hair will make it stronger.

“Leave the food in your kitchen and stick to products specially developed for your hair,” Plata said.

“There is an entire science behind the creation of haircare products. Mayonnaise, olive oil and vinegar may taste great on your salad, but will do nothing for your hair.”

He pointed out that the oil in mayonnaise can even trigger dandruff outbreaks and the lime juice it contains will strip color.

Myth 5: Any woman can use any hair color shade as long as it is applied correctly.

“Wrong, wrong, wrong,” insisted Plata.

Unless you want to look as natural as Tammy Faye Baker’s makeup, stick to a color within two or three shades of your natural hair color.

“Nature generally knows what it’s doing,” he said.

“Your hair color is perfectly matched to your eyes and skin tones, and besides, unless you dye your eyebrows, they will always be a dead giveaway of your true hue.”

Myth 6: Split ends can be mended.

“Sorry, no such luck,” said Plata.

“Certain products will make them look less visible, but the only way to really get rid of split ends is to cut them off.”

All of which brings us back to those frequent cuts to make your hair grow faster in myth number one.

So what’s the best way to care for you hair without falling prey to the lies of your stylist?

Cut it when it needs it, process it as little as possible, and stick to store-bought conditioners and shampoos, preferably free of birth control pills.