In recent years, sulfates have come under fire for being harsh on the hair and scalp, stripping hair of color, and dulling shine. But are they really to blame?
Every shampoo formula contains at least one kind of cleansing ingredient to help wash away dirt and sebum from the scalp. Sodium or aluminum lauryl sulfate (SLS or ALS) and sodium laureth sulfate (SLES) are common sulfate surfactants used in shampoo formulations.
At the molecular level, these cleansers, called surfactants, are multitaskers. Due to their unique chemical nature, when dissolved in water, they assemble into groups called "micelles," which have the ability to surround and lock in the oils in sebum and keep them suspended in water. Surfactants are also responsible for the foaming action which makes showers more pleasurable, but also "thicken" the water (à la whipped cream) so we can work it into hair instead of it slipping through our fingers.
So are sulfates bad for your hair?
In the Good Housekeeping Institute Beauty Lab, we have evaluated many shampoo formulations both with and without sulfates on hundreds, if not thousands, of testers over the years. Shampoo formulations from reputable brands are overall well-tolerated: We haven't had a single tester drop out of a study because they found the formula to be harsh.
“People had beautiful hair in decades past while all the time using sulfate-based shampoos,” says Trefor Evans, Ph.D., Director of Research and Institute Fellow at TRI-Princeton, an independent hair fiber science research organization. While Evans doesn’t rule out that sulfates could possibly be harsh on the scalp, has says any effect they might have on hair is “minimal compared to all the other things we do, such as chemical treatments, high heat, etc.”
Jeni Thomas, Ph.D., Principal Scientist for Procter & Gamble Hair and Pantene says the “harshness” of a sulfate shampoo depends on how well it's formulated.” Pantene's research has found that if sulfates or even sulfate-free surfactants are added to a formula without the proper micelle structure, they can penetrate the surface of hair or skin and disrupt the natural structure. “Micelles are the key to gentle cleansing, regardless of the surfactant used," Thomas explains. "It takes formulation experience and in-depth knowledge of micelles to get it right."
So although there is no technical evidence that sulfate-free shampoo formulas are gentler or better for hair, the consumer demand for them remains strong among women with curly, natural, color-treated, and damaged hair.
What does sulfate-free shampoo do for your hair?
One of the most touted benefits of sulfate-free shampoos is that they are better for preserving hair color. In GH Beauty Lab tests of color-protecting shampoos, there were winning formulations both with sulfates and without. This means that if a shampoo is formulated correctly, it will reduce hair color fading, regardless of the surfactants it contains. “Shampoos are not detrimental to color fading – water is!" Evans says. "We can get the same amount of color fade from a placebo water treatment as a shampoo, so this is another big consumer myth."
Even though “milder” sulfate-free shampoos claim to slow color fading even more than other color-protecting formulas, according to GH Beauty Lab testing, that's not always the case. (In fact, our Lab's top performer contains sulfates!). What really matters is how well a product is formulated, not just what it contains.
That means that a product’s effectiveness isn’t dependent on just one ingredient: All other components of the formula, like its concentration, the included surfactants and/or emulsifiers, and more have to work in perfect synergy for the product to be color-safe and deliver results. That's why we don’t recommend anything based on just one ingredient (or the lack of one ingredient) — we instead recommend products that actually perform on the whole.
Bottom line: Sulfates alone are not bad for hair — a shampoo's overall formulation is what makes a product "safe." Things like heat styling and chemical treatment are more damaging to hair and color than sulfates alone.
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