Soy Isoflavones and Chili Pepper for Hair Growth – Experiment Update

Spicy peppers contain capsaicin, which should promote hair growth. (Photo by Jonathon W)

Several readers have been asking for an update on my hair growth experiment with soy isoflavones and capsaicin. I admit it's long overdue, so here goes!

First some background on the experiment. Why soy isoflavones? I know there are a lot of people who think soy is the ultimate poison, and while I'm not a big fan of soy as a food, the science behind isoflavones and hair growth is strong enough for me to give it a go. Soy isoflavones have been shown to increase IGF-1 in the skin, which in turn promotes hair growth. Although soy also reduces DHT in rats and in humans, the effects on IGF-1 seem to be the primary way through which isoflavones grow hair.

Capsaicin seems to have a similar effect on IGF-1, and in both mice and humans, the combination of soy isoflavones and capsaicin appears to be more effective than capsaicin alone. I have not seen a direct comparison of soy isoflavones and soy isoflavones + capsaicin, however, so it's unclear how important capsaicin really is. Nevertheless, I chose to take both for the experiment.

The participants in the study were given a capsaicin supplement, but I decided to take the natural route and just add cayenne pepper or chili powder into my food instead. It's difficult to determine just how much capsaicin I've been ingesting this way, since the capsaicin content depends on a lot of variables. As I wrote when the experiment began:

The only problem is that it's pretty difficult to estimate the amount of capsaicin; a tablespoon of ground chili will contain anywhere between 0.8 mg and 480 mg of capsaicin. In the study, 7 mg per day was consumed, so if I manage to eat a tablespoon, I should have decent odds of ingesting at least as much capsaicin.

The amount of isoflavones I've been eating, on the other hand, has been easy to measure. One capsule contains 60 mg of isoflavones, which is 15 mg less than in the study.

And what about the results? I've not taken any pictures, since unlike in the retinol experiment, there's not much visible going on. I haven't cut my hair in years, and the length of my hair is still the same as it was before (the maximum length of your hair is genetically determined), so it's safe to say that isoflavones and capsaicin haven't done anything in that department.

I also haven't seen any increase in the rate of hair growth, which is perhaps a bit surprising, since you might expect an increase in IGF-1 to increase the speed at which hairs grow. But then again, I have no reliable way of measuring my IGF-1 levels either. I've simply been looking at a few hairs and measuring how much they grow each month.

The one thing I noticed during this experiment is something of a shed in the beginning. There's no way to be sure it's the isoflavones and capsaicin working, but I haven't noticed anything similar with the other experiments. After a few months, I seemed to not only shed more hairs in general, but especially from the front of the scalp. Moreover, many of these hairs had not grown to their full length yet.

As most of you probably know, that can be a good or a bad sign. A lot hair growth drugs, including finasteride, cause an initial shed, after which the hairs grow back stronger and healthier. Then again, inflammation also causes hairs to shed earlier than they should, only they grow back weaker every time.

At this point, it's still too early to tell, since the new hairs are still growing. At least on the surface they look fine. What's funny is that there are some spots where several hairs are pretty much the exact same length. The two possible reasons is that those hairs were shed at the same time and now regrowing, or that the isoflavones and capsaicin increased the number of hair follicles. I suspect the former, but I can't be sure.

So what's the next step? I've already ordered a second bottle of isoflavone capsules, and since I like to use chili in my food anyway, I'll pretty much keep doing what I've been doing so far. If I see any dramatic changes, I will post about them, but if not, I will just consider the isoflavones and capsaicin thing a preventative measure and move on to more interesting experiments.

That's it for today. I hope you found this update useful, and if you have further questions or you've done a similar experiment of your own, please let us know in the comment section.

For more information on hair growth, see these posts:

Topical Retinoids Increase Hair Growth in Most People
BioSil, JarroSil & Beer – Silicon Experiment Conclusion
Zinc Pyrithione Reduces Shedding and Moderately Promotes Hair Growth
Eclipta Alba Extract Grows Hair Quicker than Minoxidil