No matter how many luxury oils, creams, and sprays you’ve got in your arsenal to help up the shine factor of your strands, the true secret to gorgeous hair is protection. It’s why hairstylists are constantly singing the praises of pre-hot tools heat protectants, and urging you to rinse your hair with cold water at the end of every wash. And while these are important steps for keeping your hair healthy, what you may not realize is that your strands actually have a built-in protective layer of their own, and true defense against damage relies on keeping it in-tact.

Think about it like this: You’ve likely heard the phrase “microbiome” as it applies to your skin, which is essentially an ecosystem made up of an invisible layer of microbes that acts as an extension of your immune system and helps ward off infection. Well, just as your skin has this shield of armor around it, your hair also has a sheet of protection. “The protective layer of our skin can be likened to the protective layer of our hair in terms of function,” explains dermatologist Whitney Bowe, MD, author of The Beauty of Dirty Skin. “Healthy human hair is coated by seven layers of cuticle cells. The outermost layer is called the epicuticle and it helps to protect the hair from damage.” This is the layer that all of those products are working to keep healthy, in order to ensure that the strand underneath keeps doing its thing.

“When our hair’s protective layer is compromised or missing altogether, our hair loses its capacity to keep water and other harmful abrasive agents from hair-care products out,” says  Dr. Bowe. “This all results in the damage, dullness, and breakage. Additionally, an alkaline pH can actually increase the negative electrical charge of our hair fiber surface which will increase friction between fibers. This can actually lead to cuticle damage and fiber breakage, which translates into dull, damaged hair. Optimizing the pH of our hair-care products can, therefore, also benefit the overall health of our hair.”

Because of this, it’s important to invest in the right products to keep that barrier functioning properly. “Product choices make a difference when it comes to protecting your hair’s cuticle layers including the epicuticle, pH, and overall health and appearance,” says Dr. Bowe, noting that the more suds and bubbles in your shampoo, the more damage you’re actually doing to your hair. “The detergents that give you those foamy bubbles are the same detergents that are damaging the hair shaft. Detergent is actually an overachiever when it comes to cleansing, stripping your hair and scalp of the healthy oils and natural protective barrier while irritating your scalp and prompting your skin to produce even more oil to compensate for its loss.”

She suggests Aquis Prime’s four-piece system, which is specially designed with the hair barrier in mind. “We need gentle products that protect our skin’s natural barrier. The same concept applies when it comes to hair care. We want replace our harsh cleansers with gentle, clean products formulated to cleanse our hair without damaging the fragile cuticle—the outermost layer of the hair,” says Dr. Bowe. “When your hair cuticle is smooth and uniform, your hair looks shiny. When light reflects off of the smooth surface, your eye registers that reflection as shiny and healthy hair.”

And one other thing: While your strands don’t technically have an actual microbiome of their own, your scalp and follicles do, and you’ll want to take steps to properly care for those, too. “Avoid harsh cleansers and “detoxifying scalp scrubs” as these are likely to damage the good bacteria and upset the balance of the scalp. Look for naturally based products without harsh cleansers such as sulfates and clogging ingredients such as silicones,” says Dr. Dominic Burg, chief scientist and hair biologist at Evolis. “Also look for products with essential oils and botanical antioxidant ingredients, gentle moisturizers, and a balanced pH.”

Just as the pH of your hair matters, so too does the pH of your skin. And, apparently, your vagina.