The cult of coconut oil is going strong, and while a lot of the uses are pretty BS (pulling out toxins, for example), it is actually better for your hair than other oils! Here’s why, and how to best use it…
What Happens When Your Hair Gets Wet
First, we have to take a look at what happens when you wash your hair, at a microscopic level.
The outer layer of your hair is called the cuticle. It’s made up of rigid overlapping scales, full of keratin, a tough protein that also makes up a large proportion of your nails. The cuticle acts like a shield around the spongy interior of the hair, the cortex. The cortex and cuticle are all stuck together by the cell membrane complex.
When hair gets wet, the cell membrane complex and the inner cuticle (endocuticle) soak up water and swell up, but the rigid outer layer doesn’t. This makes the scales stick up, and they get snagged and snap off when strands rub against each other or when you run a comb through it. This damage to the cuticle leads to split ends and breakage.
How Can Oil Help?
There are 2 key ways that oiling hair can help. When oil is applied on hair after washing and before combing, it lubricates the hair so there’s less friction, leading to less snagging.
More powerfully though, adding oil to hair before washing, the oil coats the hair in a protective layer. Since oil is water-repellent, less water will get inside the hair, so there’s a lot less swelling. The cuticle scales stick up less, so less damage occurs.
Why Is Coconut Oil the Best Oil for Hair?
Coconut oil is particularly good because its structure means it can penetrate the hair shaft more than most other oils, leading to a stronger water-repellent effect. Here are the average structures of mineral oil, coconut oil and sunflower oil (all three are actually complex mixtures):
Coconut oil performs better than both sunflower oil and mineral oil in preventing damage to wet hair.
Compared to sunflower oil, coconut oil molecules are smaller. Coconut oil has shorter fatty acid chains – about 50% lauric acid, which is 12 carbons long, and 20% myristic acid, which is 14 carbons long – while sunflower oil is 60% linoleic acid and 30% oleic acid, which are both 18 carbons long. Additionally, coconut oil contains mostly linear saturated fatty acids while sunflower oil is mostly bent unsaturated fatty acids, which means that coconut oil molecules are more compact as well. This means it’s easier for coconut oil to pass into the cell membrane complex, which boosts its ability to form a water-blocking layer.
Mineral oil molecules contain around 20 carbons, so they’re actually substantially smaller than coconut oil molecules which contain around 40 carbons. It’s the oxygen atoms in the coconut oil this time which makes it work better for hair – the oxygen atoms allow the coconut oil to interact with hair proteins via hydrogen bonding, and be sucked into the inner part of the hair.
How to Use Coconut Oil to Reduce Hair Damage
So here’s how you should be using coconut oil in your routine:
1. 5-10 minutes before washing, rub coconut oil into your hair (if it’s solid, warm it up in your hands first)
2. Shampoo and and condition normally
3. If you want, you can also rub some oil into your hair after washing
Conveniently, this also means that you won’t have to go around with greasy hair – the shampooing will remove a lot of the applied oil anyway! If you don’t have a favourite brand of coconut oil yet, I love the strong coconut smell of Nutiva, but any old coconut oil will do! And if you’re interested in more uses for coconut oil, this article has a whole list of health benefits.
AS Rele & RB Mohile, Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage, J Cosmet Sci 2003, 54, 175–192.
K Keis, D Persaud, YK Kamath & AS Rele, Investigation of penetration abilities of various oils into human hair fibers, J Cosmet Sci 2005, 56, 283–295.
SB Ruetsch, , YK Kamath, AS Rele & RB Mohile, Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: relevance to hair damage. J Cosmet Sci 2001, 52, 169–184.
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