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Coconut oil for hair: what the protein-loss study found, and how to use it

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Coconut oil has been rubbed into hair for generations.

Now it's on every beauty shelf, with promises to repair damage, stop breakage and grow thicker hair. You may have a jar in the kitchen and wonder whether rubbing it into your hair is genuinely useful or just greasy. The good news is that this is one of the few coconut claims with real laboratory science behind it. The bad news is that the most popular claim, hair growth, is the one with the least.

Three moves: what the claims are, what the studies found, and how to use coconut oil on your hair in a way that matches the evidence.

Part 1: The claims

Coconut oil for hair is marketed to do four things:

  1. Prevent damage from washing, brushing and styling.
  2. Strengthen hair so it breaks less.
  3. Add shine and softness.
  4. Make hair grow faster or thicker.

The first two are about the hair shaft, the part you can see, which is not alive. The fourth is about the follicle, which is alive and sits under your scalp. That distinction matters, because the research almost entirely covers the first two.

Part 2: What the research shows

The famous protein-loss study

Most articles about coconut oil and hair trace back to one 2003 paper in the Journal of Cosmetic Science, by researchers at Marico, an Indian company that makes coconut hair oil. That's worth knowing upfront.

They compared coconut oil, sunflower oil and mineral oil applied to hair before and after washing, on undamaged and damaged hair. Coconut oil was the only one of the three that remarkably reduced protein loss, for both kinds of hair. Sunflower and mineral oil "do not help at all" in reducing protein loss, the authors wrote (Rele 2003).

Why does protein matter? The 2003 study's premise is that washing and grooming draw protein out of hair, and that losing it weakens strands (Rele 2003). Later work showed shampoo surfactants dissolve protein inside the hair and increase its porosity (Kaushik 2022).

Then comes the mechanism.

The researchers argued that coconut oil's main fat, lauric acid, has a high affinity for hair proteins, and its small, straight molecule can slip inside the hair shaft. Mineral oil, a hydrocarbon, doesn't bind proteins. Sunflower oil's main fat has kinks from double bonds that make it too bulky to get in (Rele 2003).

A 2001 study had already tested that idea with a mass spectrometry technique that maps where molecules sit inside a hair cross-section. It found coconut oil penetrates the hair shaft while mineral oil does not (Ruetsch 2001).

Here's the picture. Imagine a hair strand as a rope made of tightly packed fibers. Washing with shampoo is like soaking the rope in soapy water: the soap seeps in and loosens fibers, and some wash away. Mineral oil coats the outside of the rope like a raincoat. Coconut oil soaks into the gaps between the fibers, so the soap has fewer places to go.

Newer studies: it's not only coconut

Later work added nuance.

A 2022 study measured hair porosity, the tiny internal spaces that open up as shampoo damages hair. Coconut-based hair oils prevented the increase in porosity, reversed losses in breaking strength, and protected hair color (Kaushik 2022). A 2021 study found coconut oil significantly increased the strength of twisted hair fibers compared with mineral oil, especially after repeated wash cycles (Kaushik 2021).

But a 2024 study in the International Journal of Cosmetic Science found that many plant oils, with a range of fat types, can penetrate hair, with shorter-chain fats penetrating more. All the plant oils tested improved hair's resistance to fatigue breakage (Marsh 2024). And a 2022 study found a different hair oil formula penetrated and strengthened hair more than coconut oil did (Sureka 2022).

So coconut oil is good at this. It may not be uniquely good.

The catch: these are lab studies on hair, not people

Almost all of this research was done on hair swatches or single fibers in a lab, using machines that stretch and twist strands. That's legitimate science for measuring the hair shaft. It doesn't tell you how your hair will look and feel after a month of oiling, and it was often done by researchers connected to hair oil makers (Rele 2003). A 2019 narrative review summarized it fairly: coconut oil products "may also be useful in preventing hair damage due to protein loss," but more studies are needed to confirm the effect (Wallace 2019).

Hair growth: no good evidence

Now the claim that brings most people to this page.

We searched for clinical trials showing coconut oil makes hair grow faster or thicker in people, and found none we could verify. The protein-loss and penetration studies are about the shaft, which is dead tissue. They say nothing about follicles. Hair loss has many possible causes, and none of the studies in this article tested coconut oil as a treatment for any of them.

That's the honest answer. Unproven.

Part 3: How to use coconut oil on your hair

The studies point to a simple principle: get the oil into the hair before you wash, so it's there when shampoo does its damage.

A routine based on the research

  1. Pre-wash treatment. Warm a teaspoon to a tablespoon of virgin coconut oil between your palms (more for long or thick hair). Work it through the lengths and ends, where hair is oldest and most damaged.
  2. Leave it on. The 2021 study used overnight oil treatments (Kaushik 2021). If overnight isn't practical, give it at least some time before washing.
  3. Shampoo as usual. You may need two rounds to remove the oil.
  4. Optional: a tiny amount after washing on the ends, if your hair is dry. The protein-loss study tested both pre-wash and post-wash use (Rele 2003).

If you have fine or oily hair, start with less and keep it off your roots.

Best coconut oils for hair

You don't need a special "hair" coconut oil. The research used plain coconut oil.

Viva Naturals Organic Extra Virgin Coconut Oil is our top pick for hair because the larger tubs make sense if you oil weekly, and it doubles as a kitchen oil.

Nutiva Organic Virgin Coconut Oil is the organic, unrefined benchmark jar. Keep a separate jar in the bathroom.

Dr. Bronner's Organic Virgin Coconut Oil is the fair-trade alternative if sourcing matters to you.

Pick one without added fragrance. Fragrance adds no benefit the studies measured.

Virgin or refined for hair?

We found no study comparing virgin and refined coconut oil on hair. The penetration argument rests on lauric acid's size and shape (Rele 2003), and the fatty acid profiles of virgin and refined coconut oil are similar (Wallace 2019). So in theory either should behave the same way inside the strand.

In practice we lean virgin for one reason: you're less likely to get a product with added fragrance or processing you don't need, and the smell washes out. If you dislike the coconut scent, refined oil is a reasonable choice, but that's our judgment, not a tested finding. If you already own Viva Naturals Organic Extra Virgin Coconut Oil for cooking, a second jar of the same oil is all your bathroom needs.

A balm option for ends

Kopari Coconut Melt is a coconut-based balm that's easy to warm in your hands for ends and flyaways. We're still reviewing its full ingredient list, so if you have sensitive skin, patch-test it first; plain virgin coconut oil is the option that matches the studies most closely.

Brush gently

Oil helps protect hair from the stress of grooming, but how you brush matters too. The 2021 study found twisting and stretching together were especially damaging to strands (Kaushik 2021). A soft boar bristle brush is a gentle option for distributing oil through dry hair. We include it as a practical tool, not a studied treatment.

Who should be careful

If you have a scalp condition such as seborrheic dermatitis, or your scalp gets itchy or flaky with oils, check with a dermatologist before applying coconut oil to your scalp. And if your hair is falling out, see a doctor. That's a medical question.

The bottom line

Coconut oil is one of the better-studied hair oils. Lab studies show it can penetrate the hair shaft and reduce the protein loss caused by washing (Rele 2003; Ruetsch 2001). Other plant oils can do similar things (Marsh 2024). There's no good evidence it makes hair grow.

Tonight, warm a teaspoon of Nutiva Organic Virgin Coconut Oil in your palms, smooth it through the bottom half of your hair, sleep on a towel, and compare how your ends feel after your next three washes.

This article is for general education and is not medical advice. If you have a health condition, take medication, or are pregnant, talk to a doctor or registered dietitian before changing your diet or skincare.

Sources

  1. Rele AS et al. (2003). Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. J Cosmet Sci. PubMed: https://pubmed.ncbi.nlm.nih.gov/12715094/
  2. Kaushik V et al. (2022). Benefit of coconut-based hair oil via hair porosity quantification. Int J Cosmet Sci. PubMed: https://pubmed.ncbi.nlm.nih.gov/35377477/ | DOI: https://doi.org/10.1111/ics.12774
  3. Ruetsch SB et al. (2001). Secondary ion mass spectrometric investigation of penetration of coconut and mineral oils into human hair fibers: relevance to hair damage. J Cosmet Sci. PubMed: https://pubmed.ncbi.nlm.nih.gov/11413497/
  4. Kaushik V et al. (2021). Single hair fiber assessment techniques to discriminate between mineral oil and coconut oil effect on hair physical properties. J Cosmet Dermatol. PubMed: https://pubmed.ncbi.nlm.nih.gov/32949101/ | DOI: https://doi.org/10.1111/jocd.13724
  5. Marsh JM et al. (2024). Penetration of oils into hair. Int J Cosmet Sci. PubMed: https://pubmed.ncbi.nlm.nih.gov/38922913/ | DOI: https://doi.org/10.1111/ics.12978
  6. Sureka P et al. (2022). A Method to Measure Oil Penetration into Hair and Correlation to Tensile Strength. Int J Trichology. PubMed: https://pubmed.ncbi.nlm.nih.gov/36081445/ | DOI: https://doi.org/10.4103/ijt.ijt_122_20
  7. Wallace TC et al. (2019). Health Effects of Coconut Oil-A Narrative Review of Current Evidence. J Am Coll Nutr. PubMed: https://pubmed.ncbi.nlm.nih.gov/30395784/ | DOI: https://doi.org/10.1080/07315724.2018.1497562

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