Saturday, January 7, 2017

Does Castor Oil Really Work to Re-Grow Hair?

You may have read online that castor oil can be used to re-grow thinning hair, patchy eyebrows, or sparse eyelashes. But is there any science behind this popular internet claim?

To find out, I started with a search of the National Library of Medicine (Pubmed)--a database of all published studies on substances synthetic and natural alike. Castor oil has been used for many years to help ease osteoarthritis, and there is a limited body of evidence confirming this practice. However, searching for any articles regarding its ability to re-grow hair came up empty.

After searching many variations of "castor oil" and "hair," through Pubmed and continuing to find no results, I took to the general internet and found this article. It says the science behind castor oil's ability to re-grow hair is such:
Accounting for more than 90% of castor oil’s constitution, ricinoleic acid is the single largest component, is mono-unsaturated and features 18 carbons. What renders it different is that its 12th carbon comprises of a hydroxyl functional group. It is courtesy of this structure of ricinoleic acid that castor oil derives its polar nature and hence is chemically more nourishing for the scalp. 
Hair growth is spurred by a lipid compound named Prostaglandin (PGE2) and it could be best described as a catalyst. While its presence in high concentration promotes growth of hair, its depletion causes hair loss and eventually leads to baldness. Castor oil’s principle component – ricinoleic acid – has been scientifically proven to stimulate the production of Prostaglandin (PGE2) when applied to the scalp. Enhanced production of this lipid, particularly in bald spots, enriches hair follicles and encourages regeneration of hair.
It sounds legitimate--there are chemical names and diagrams, and even sources cited. But the science behind the claims have been misinterpreted in more ways than one.

Yes, the fatty acids in castor oil are primarily ricinoleic acid. However, oils don't just contain free fatty acids. In castor oil, the fatty acids are arranged in to molecules called triglycerides: three fatty acids held together by a glycerol group. (Aka glycerin.) So, while castor oil can easily be broken down to extract ricinoleic acid, castor oil in its raw state doesn't contain free ricinoleic acid. Putting castor oil on your skin and hoping it will affect your prostaglandins is like putting a bottle of Aspirin on your head and hoping it will get rid of your headache. Essentially, the ricinoleic acid is still in its "wrapper" in castor oil.

I did find one study that shows how ricinoleic acid can affect prostaglandins, however, it was when taken internally. The digestive system is able to break down the castor oil and turn it in to free ricinoleic acid, which can interact with prostaglandin receptors and create a laxative effect and potentially be used to induce labor. Prostaglandins do have some kind of mechanism in the hair follicle, however, their function continues to be unclear. And the effects of putting ricinoleic acid on hair is also unclear.

Castor oil is a safe ingredients to use, and I am sure that there are reports that it appears to have helped re-grow hair for some people. However, there is no science to back these claims.

What about you? Have you tried castor oil to spur hair growth? What were your results?

Related material:
The downside to castor oil
5 Natural Remedies for Hair Loss


Unknown said...

I always love reading your blog. I've always just associated castor oil with laxatives, so, no. I haven't used it to try to grow hair. Haha!


Anonymous said...

I can personally attest for castor oil's ability to induce labor. In a nutshell: IT WORKS! :-)

Living Day 2 Day with Purpose said...

Living Day 2 Day with Purpose said...

Stephanie Greenwood said...

@Living Day 2 Day with Purpose---

Is there something that you're saying with these links? These are indeed good examples of claims on the internet that castor oil will grow hair.

Anonymous said...

I've always associated castor oil with inducing vomiting so it's been hard to shake that association with anything else. It can also be used to induce labor. It's also one of the oldest folk remedies that is added to packs and placed on the body for purging toxins. Your largest organ the skin can absorb and release medicine transderminally so I don't see why it cannot absorb castor oil and break it down into a simpler form.

Anonymous said...

I have been trying it in my hair for the past month. I don't know that it made more hair growth, but it seems like my little gray hairs are not as noticeable. Id be curious to find out if it helps hair keep its pigment rather than grow gray.

Anonymous said...

My experience with Castor Oil has been positive. I first tried on my eyebrows. I had a bad experience with someone who didn't shape one of my eyebrows properly and ended up taking off the end of one of my eyebrows. After a year or so of that part of my brow not growing back, my hair dresser mentioned Castor Oil. So I tried it. After about a week and 1/2, the hairs started growing back. I also have fuller eyebrows and am pleased with the result. I then tried it on a thinning part of my hairline and it was the same thing, little hairs started growing (peach fuzz)and now, after about 5 months, I have almost 4 inches of length of hair growth in that area. I am completely convinced. I passed on the information to my mother who grew up during a time when women completely removed their eyebrows and penciled them in. Hers never grew back. She's been using the castor oil for a couple of months now and is experiencing the same thing. Hairs are growing in. It certainly doesn't hurt to give it a try. If it works for you, great. If not, you are out about $13 for a 16 fluid oz. bottle of organic, cold pressed pure castor oil.

I wonder too, if the reason there is no real scientific info on the subject is because it hasn't actually been studied. It seems like it would be studied more given the problem with alopecia, male pattern baldness, etc. and the extremes people have been willing to go to have hair.

Anonymous said...

Hi Stephanie,

I was reading your article about the exposed "organic" shampoo. You have a gift for explaining complex things in an understandable way! Reading your article made me wonder what makes my shampoo lather! The oils are not saponified as far as I know, and I just figured it must be the glycerin. But there's nothing to bind the oils/extracts, glycerin, and water together... unless apple cider vinegar can do that, which I rather doubt! I would be so glad to know what you think about it. Here's the link:

I've also been using another brand that Is EcoCertified, but not as "natural-looking." Here's the link for that one also:

I didn't realize that you had a hard-water shampoo! Just saw it the other day, but I had to search for it on your site. It didn't show up with the other two that you carry. Is it still available?

Okay, one last question... I'm curious what your opinion is on the very popular Norwex cleaning cloths. They have "micro silver" in them (I would hope not nano). Do you think that regular use could be bad for immune health (like antibacterial soaps) or pose any other risks?

Thank you so much!

Stephanie Greenwood said...

@Rachel--Thanks for reading! Great questions here.

re: the Rocky Mountain Shampo--yes, indeed those ingredients do not add up! (For their conditioner, too.)

The Green Beaver product looks like it's a full disclosure of ingredients at least. Doesn't look terrible.

Oh yes, the hard water shampoo! Link:

Norwex--I think that there's probably not enough info right now to fully assess the safety of those cloths long-term. In general I'm not a fan of anti-bacterial agents.

Anonymous said...

Thanks so much, Stephanie! That's so helpful and good to know!

Also in case this is helpful to anyone, the RM shampoo bottles say ELEMENTS, not Ingredients. I guess that way they won't get in trouble, but can still make their product look good? *Sigh* So sad.

I'm excited to try your hard water shampoo next order. :) Green Beaver it is until then.

Thanks SO much!

James B. said...

Thanks for this really interesting case study you've done!
I've been looking for more details about Castor oil and if it actually works for hair growth. Many people I've seen talking about it on the internet are discussing whether it's as good as everyone says it it, so it's nice to see some objective views like yours.

Thanks! :)

Bradley Fowler said...

Really very informative article. Thank you for sharing with us! I have tried castor oil or coconut oil when I was suffering from hair loss problem. I got an awesome result by using these natural hair growth products .

Anonymous said...

I have been using castor oil on my eyebrows and lashes about a month now. There is actually a lot of hairs coming in but they are all blonde like peach fuzz! Weird! I was thinking about tinting my brows now.