Sunday, September 20, 2009

Capsaicin and Soy Isoflavones Promote Hair Growth

A teaspoon of dried chili pepper has enough capsaicin to increase IGF-1.
A teaspoon of dried chili pepper has enough capsaicin to increase IGF-1. (Photo by Giuliagas)

This is the third post in a series about the effect of soy on hair growth. So far, we've seen that soy protein reduces DHT in men, and that soy isoflavones reduce DHT but increase testosterone in mice. While this seems like a good thing from a hair loss perspective, it doesn't guarantee that eating soy will actually prevent balding. So, time for some more studies.

The paper we'll look at today suggests that a combination of isoflavones and capsaicin grows hair in mice and in humans (link). The mice received capsaicin via injection and isoflavones through their diet, while the human participants took both orally as supplements.

Study method

For the mouse study, the mice were divided into three groups: one received capsaicin only, the second received capsaicin and isoflavones, and the third was a control group. Though the full paper doesn't explicitly state soy isoflavones anywhere and just talks about isoflavones in general, the "Fujiflavone P40" product they used in the diet is extracted from soy beans, so we can assume that the results apply to soy isoflavones.

The human study included 48 volunteers, 25 men and 23 women. 34 suffered from androgenetic alopecia (AGA), 13 from alopecia totalis (AT), and one from alopecia areata (AA). The participants were randomly divided into two groups: the first one received 6 mg capsaicin and 75 mg isoflavone daily, and the second received placebo only.

Capsaicin and IGF-1

Insulin-like growth-factor 1 (IGF-1) is involved in promoting hair growth in humans and animals. Indeed, mice that have been genetically modified to overexpress IGF-1 develop hair follicles earlier than controls, and humans with an IGF-1 deficiency have sparse hair growth. One explanation is that IGF-1 produced by dermal papilla cells might promote hair growth through stimulation of keratinocyte proliferation in hair follicles.

When the mice in this study were administered capsaicin, their dermal levels of insulin-like growth-factor 1 (IGF-1) increased significantly. On the other hand, CGRP-knockout mice did not show increased IGF-1. The authors suggest that increased CGRP, or calcitonin-gene related peptide, production leads to increased IGF-1, which in turn leads to hair growth.

In mice, the combination of capsaicin and isoflavone increased IGF-1 more than capsaicin alone. This makes sense, since isoflavone increases CGRP production. In humans, IGF-1 levels were increased after 5 months in the participants taking capsaicin and isoflavone orally, while they were not increased in those receiving placebo.

Capsaicin, isoflavone and hair growth

After four weeks of treatment, the rats receiving either capsaicin or capsaicin and isoflavone had grown more hair then the control rats. Consistent with the observed increases in IGF-1, the combination of isoflavone and capsaicin was more effective than capsaicin alone.

Effect of cayenne and isoflavone on hair growth in mice
The leftmost image above shows three of the control rats after 4 weeks. The center image is of the capsaicin group, and the rightmost image is of the capsaicin + isoflavone group.

After 5 months, hair growth was significantly increased in 64.5% of human volunteers administered with capsaicin and isoflavone, compared with 11.8% in the placebo group. Furthermore, 88% of the participants suffering from androgenic alopecia saw a promotion of hair growth when given capsaicin and isoflavone. This suggests that the treatment might be more effective for male-pattern baldness than other types of hair loss. Below are some samples of the humans treated with oral capsaicin and isoflavones.

Effect of cayenne and isoflavone on hair growth in humans
The upper left picture (a) is of a 54-year-old male with androgenic alopecia. That's a pretty significant result right there. The picture in the upper right corner (b) is of a 29-year-old male with alopecia totalis. Some hair growth is evident, but not a full recovery. The lower left corner (c) is of a 39-year-old female with androgenic alopecia, showing some thickening of the crown area. The lower right corner (d) is of a 40-year-old female with alopecia areata.


A combination of soy isoflavones and capsaicin increases dermal levels of IGF-1 and promotes hair growth in humans and mice. While some in vitro studies have suggested IGF-1 to be deleterious to hair growth, this study shows that the result may be different in vivo.

The amounts used in the study are quite reasonable. Chilli, cayenne pepper and red pepper contain between 0.1 mg to 60 mg capsaicin per gram (link, link, link, link). Given that a tablespoon of ground spice weighs about 8 grams, one tablespoon of ground chili pepper would contain anywhere between 0.8 mg and 480 mg of capsaicin. The hotter the pepper, the more capsaicin it contains.

As for soy, the best source of isoflavones are soy beans, which contain about 200 mg isoflavones per 100 grams (link). Tofu contains ~35 mg per 100 grams, while soy milk contains only ~9 mg. Thus, to get the 75 mg used in the study, you would either need to eat about 40 grams of soy beans (dry weight), a little over 200 grams of tofu, or a little less than a liter of soy milk.

Both capsaicin and soy isoflavones (mainly daidzein and genistein) are also commonly available as supplements.

For more information on soy, cayenne and hair growth, see these posts:

Do Flax Lignans Reduce Hair Loss from MPB?
Soy Protein Isolate Reduces DHT in Healthy Young Men
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
Emu Oil and Hair Growth: A Critical Look at the Evidence

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27 kommenttia:

Aaron September 22, 2009 at 12:42 AM  

nice article -- now my question is: do you consume soy? Do you think soy milk is safe as long as you have adequate iodine status?

JLL September 22, 2009 at 10:13 AM  


I don't eat soy, no. I have tried soy isoflavone supplements for a little while, but I'm planning on a longer experiment later on. I haven't really read enough about soy milk to judge its safety.

I used to be quite anti-soy before, but reading about the health benefits of isoflavones has made me change my mind somewhat.

Anonymous September 28, 2009 at 9:43 PM  

how do you contrast the attractive physical results of this approach to the LT health risk of intentionally increasing IGF-1 that is often linked to various cancers?

perhaps androgenic balding is part of a defense mechanism against cancer.

Anonymous September 30, 2009 at 1:59 AM  

Can you help me? I would like to know the link of this study.

Thank you for your research.

JLL September 30, 2009 at 9:27 AM  


That's the first time I've heard of balding being a mechanism against cancer -- if it is, it doesn't seem to be a very good one. As for increased IGF-1 and cancers, I can't really say. Some studies point to IGF-1 being good, others say it's bad. It probably depends also on what it is that is increasing/decreasing IGF-1.

It'd probably be better to have only a local effect on the scalp, which is what the authors measured; apparently it can be done by injecting the stuff into scalp skin. Whether applying them topically like a shampoo would help, I don't know.

The link is there in the beginning of the post, but here it is again:

soydude October 23, 2009 at 8:14 PM  

After reading your article I've started a treatment, 80mg soy isoflavones daily....after reading some propecia experiences...most of them after 2 years they started to see really good results...... I've read lots of soy articles that I would like to share with you.
Great work on your blog!

Tintin March 5, 2010 at 3:27 PM  

I don't eat much soy- a little endamame, almost daily, but maybe I'll add some to my diet now. I used to use a shampoo with capsaicin in it, but I didn't notice any real effect. Those things are tough to assess without prolonged use, however. I've tried capsaicin tablets/capsules, but they tended to cause an uncomfortable burning sensation throughout my GI tract.

Anonymous March 9, 2010 at 10:36 PM  

Do you know where I could find a supplement with 6mg capsaicin? Or, if someone wanted to begin a similar treatment, could you recommend two products? The only capsaicin supplements I can find are cayenne, and then only one that lists its capsaicin content says it has .25%. Out of a 450mg capsule, .25 percent is only 1.125mg, and this study used 6mg. So, any products out there that you know of?

JLL March 16, 2010 at 12:22 AM  


Nope, unfortunately I'm not aware of any good high-capsaicin supplements. If you don't mind the spiciness, adding cayenne pepper to foods seems like a decent choice.

There was a mistake in my calculations btw; it's corrected now.


Anonymous May 5, 2010 at 5:40 AM  

anyone been on this for 3-4 months, showing any reults?

i have read somewhere this causes an initial shed period, which usually happens when starting a hair loss treatment, i wanted to know if this has occurred to any one?

leave a response on here for anyone wishing to comment.

Anonymous June 8, 2010 at 6:57 PM  

so anone been on this for some time? update us?

Anonymous June 15, 2010 at 10:38 PM  

Hi all, Ive started Isoflavones and capsi tablets, some initial discomfort in the GI tract. No change in hair loss yet but its only been 2 weeks, HOWEVER my skin has cleared up- the is a link with acne and DHT right? i think this is a good sign, hoping to see some results on my scalp soon too!

peter_seriously_enough August 17, 2010 at 7:40 AM  

Where are you getting these capsaicin tablets?

Unknown September 2, 2010 at 6:15 PM  

Thanks for the update. Which Isoflavone and capscian supplments are you taking?

JLL September 2, 2010 at 9:05 PM  


I take NOW Foods Soy Isoflavones. The capsaicin I get from chili powder, not supplements.


Anonymous January 10, 2011 at 12:10 PM  

JLL, any updates on your soy isoflavones and capsaicin experiment so far? Have you seen any increase in hair growth, regrowth, or thickening? It's been several months since your last update. We're already in 2011 now. :)

Unknown March 21, 2011 at 6:26 PM  

Hello, well I have been using cayenne and soy for about 1 year now and yes definitely it has been successful. What I do is hand fill the empty capsules with store bought spice and take one in morning and one at night with really COLD water this way you don't get that burn. I buy the soy from vitaming store the 450 mg one and take one in morning and one at night. There are so many pieces of hair growing it looks as though I had a weird haircut. I also put some rosemary essential oils into my shampoo 120 drops to 8 oz. Look for a shampoo without sulfates, very important. So far all of these things together have worked for me. Good Luck!

Anonymous May 16, 2011 at 12:40 AM  

Hi. I enjoy your articles and all of your research, thank you for doing this. However I wanted to post my initial results with the soy/capsaicin combination and I can say that it made my hair thinner! I am also taking finasteride daily to protect against DHT, so perhaps this was too much? I don't know. But after I stopped the soy/capsaicin combination, my hair gradually returned to normal but it took some time.
Has any other person noticed hair thinning as a result of taking this combination of supplements?

JLL May 16, 2011 at 12:06 PM  


How long did you take the combination for?

Anonymous May 18, 2011 at 5:04 AM  


I took the combination for 2 months. Upon examining hairs that had shed, I noticed that invididual hairs were thicker at the tip, but thinner at the hair bulb. At first I just figured these hairs would grow back thicker; however, that didn't seem to happen, my hair seemed to be getting thinner overall so I stopped the treatment.
I read that apple polyphenols might help with hair growth, have you read this too?


Carol June 26, 2011 at 6:33 AM  

Interesting post. I never thought these combination could improve hair growth. I'm just afraid of it's after effects.

Anonymous September 8, 2011 at 8:29 PM  

Now has a 500 mg Cayenne supplement at

Anonymous December 23, 2013 at 8:03 PM  

Soy is toxic in most of its presentations but those fermented non-GMO and it is very hard to know the isoflavone sources. If it is used as a DHT blocker/hormone supresor, it would be smarter to try other natural options as Saw Palmetto, Nittle root, Beta-Sitosterols, Pomegranate, L-arginine, etc.

JLL December 24, 2013 at 1:48 PM  


Got any studies to back that up? I bet nettle root is toxic in high enough concentrations. The dose makes the poison.


Hane May 27, 2014 at 5:04 PM  


Any updates with prolonged use?

Anonymous March 25, 2015 at 2:23 PM  

Hi, I have been buying soya milk (whole bean) and cayanne pepper capsules for four months now along with Saw palmetto thats in an alcohol solution. I drink one glass of soy milk followed by a cayanne pepper capsule every night and then apply a few drops of Saw palmetto to my bald area. I have noticed quite a significant improvement in the number of new hair follicles, at first they were quite fine but are looking thicker. Hope this helps give a little hope to those people losing thier hair.

Anonymous July 8, 2015 at 4:15 AM  

Hi Anonymous

Are you suffering from any type of Alopecia or just thinning with age?

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