But there is still a lot of misinformation and confusion out there. So we combed through the research (as a forewarning, there’s not a ton) as well as talked to a few of our go-to experts to find out the deal. Here, everything you need to know. Olive oil plays a role in helping hydrate hair but not in the way you might think: Olive oil is a monounsaturated fat. Hair actually has the ability to absorb monounsaturated fats, according to research1. (According to one study21, they’ve been able to document the absorption of certain oils by tracking the thinning film that surrounds the strand, and it also shows that doesn’t happen with all oils, like mineral for example, so while some smaller oil molecules can penetrate hair, some will only sit on top.) And when olive oil is absorbed into the hair, it can actually help hair retain hydration. Retain is the key word here: “Oil is not a conditioner, only water-based products can truly moisturize your hair,” says hairstylist Gabrielle Corney. “These oils have many hair benefits, but they work best when in conjunction with a water-based hydrating cream.” Liken it to using an oil in skin care; they are most hydrating when tapped on top of a lotion or essence to help “trap” in the water. It should be noted that these benefits only come when choosing the right type: Opt for extra-virgin organic olive oil, which is the least processed and contains more of the hair-helping nutrients explained above. RELATED: Olive Oil For Skin: 9 Uses & Benefits From Dermatologists There are many claims that it can help with dandruff by moisturizing flaky, scaly patches—as well as being antimicrobial. However, most dermatologists refute this. According to board-certified dermatologist Whitney Bowe, M.D., “Dandruff is caused by a yeast on our scalp, and if you use olive oil, you are feeding that yeast, which might make dandruff worse.” (She also notes she’s not against using olive oil as a hydrator, especially on the ends, but it might not be right for everyone.) Another potential side effect: If you are acne-prone on your chest or back, and your hair is long enough to touch the area, you might be unintentionally clogging pores and leading to worse breakouts. Finally, never use olive oil before using hot tools or a blow dryer. Olive oil has a burn temperature starting as low as 320°F. Most hot tools and dryers on the market go well above that. Translation? You are literally cooking your strands. However, it’s too heavy of an oil for those with fine or straight hair. It will weigh down strands and make the style appear greasy, especially when applied at the roots. These hair types would benefit more from a thinner option with less slip, like jojoba or argan oil. You might be tempted to use olive oil on color-treated hair, specifically if you lighten it, as bleaching hair opens up the hair cuticle, making it more porous as well. However, olive oil has a rich gold tone, which over time, can slowly make hair dye appear warmer or even yellow. “Any hair product that’s not clear has the potential to alter color,” says colorist and co-founder of the salon Spoke&Weal Christine Thompson. “So if you apply a product, like an oil, that has a specific tone, your hair can adapt that color with repeated use.” As a pre-shampoo treatment: As noted above, washing your hair can actually cause damage to the strands through friction and surfactants. So before you take a shower, evenly apply oil—the amount will depend on length and thickness. If you are especially dry, we recommend coating the whole strand. Or if you are prone to oily scalps, you can just focus on mid-shaft to the ends. For tending to your ends: While nothing can fix dry and split ends besides a trim, you can temporarily improve the look of them. It’s as easy as applying a tiny bit to the bottom of the hair: The oil adds shine to the area, making it appear less damaged (dullness is a key sign of dead ends). And, while this particular study didn’t test olive oil specifically, it showed that regular use of oils in general may help prevent future split ends by protecting it from physical damage. For smoothing back frizz: Applying oils gives the appearance of frizz reduction by coating and sealing the cuticle. (As a briefer on frizz: It’s caused by raised cuticles on the strands, which causes the individual strands to separate.) As we’ve mentioned before, olive oil is likely too heavy for some hair types to use as a styling agent, but if your hair is prone to extreme frizz, it can help combat fly-aways. To apply: Use a small amount, and with your fingers, comb it through your hair, focusing on your hairline or part, which tend to attract more frizz.