All the rage : Brazilian Keratin Treatment

The lovely Milan recently blogged about the brazilian keratin treatment (BKT) and asked yours truly, what is the deal with this treatment?

The advertisement

1. BKT product (usually contains keratin and formaldehyde) is applied to hair

2. Flat iron the hair (several passes - 5 to 8) at a temperature of 450F

3. The result, flat sleek hair and curls will reappear and be frizz free

The reality

1. There is no science paper that I could find which could attest to the treatment claims (meaning no paper on the formula, the method or the effect). In fact the best article I read was from Allure magazine

2. By now we all must know that protein treatments do not change hair texture. In fact proteins are known to simply stick to hair (adsorb) temporarily. Therefore in my opinion it is probably a severe case of hogwash to claim that the keratin is responsible for the straightening effect.

3. Some BKTs do contain formaldehyde in varying degrees. Now it is important to say that chemicals which release small amounts of formaldehyde are routinely used to preserve hair products such as hair conditioners and the like. However, the formaldehyde released from preservatives is usually much less than the 'safe level' of 0.2%. Some BKTs have as much as 2% to 22% formaldehyde (see the Allure article).

Q: What is the big deal about formaldehyde?

Formaldehyde is known to disrupt DNA and therefore it could cause cells to mutate and possibly cause cancer. It is defined as a probable or known carcinogen (cancer causing agent)

Q: Can formaldehyde straighten hair?

Experimentally depending on pH and heat, formaldehyde can crosslink to wool (which is similar to hair, they are both keratin based). This reaction does break bonds in the hair but whether this effect actually 'straightens' hair has not been published. (Biochem Journal, 36(3-4): pp 294–302, 1942)

Q: What is my theory on the straightening effect?

The heat to me appears to be the culprit. I have previously discussed the effect of heat on hair. At a temperature of 450 F which is a requirement of the BKT, let me be clear, the hair begins to melt and this cannot be reversed. You can read more details on the effect of heat in this post here.

Bottom Line

Would I recommend this treatment? Flat out No, Never, No!! I generally try to be unbiased but something about placing formaldehyde on your hair, burning it into the hair with hot ceramic and inhaling the fumes leads me to put on my super scientist costume and say, NO. Now I do know there are formaldehyde free formulae on the market which are essentially just protein treatments. I still wouldn't recommend the flat iron treatment but the formaldehyde free formulae are probably ok.

I think that if you are looking to straighten your hair, get a good heat protectant and flat iron it! If you want to eliminate frizz, experiment with different hair products!

Have you done or are you thinking about a Brazilian Keratin Treatment?


  1. YAAAAAAAAAAAY! Thank you for posting on this! And so fast! I wasn't expecting you to cover it right away.

    GREAT article and I totally agree with you and the information you presented. Like I stated on my blog, I have no interest in trying this. Too damaging but maybe some are ok with damaging their kurls. At least many that have read your post will be able to make an educated decision about it.

  2. This sounds scary. I don't get the whole "do anything to get straight hair" stuff. And when I first read this, not knowing what you know about chemicals and stuff, it was so obvious to me that what was straightening the hair was the 450 degrees of heat! Duh.

  3. Interesting, I'm glad you brought up using a good heat protectant. I was wondering, are any of those any good/effective?!

  4. Great article, but I have to comment on a couple of things...
    While some of the Keratin treatments currently available do contain Formaldehyde, (generally ones produced in the US), the use of this dangerous chemical is not that prevalent in Brazil, wheere the treatment began life.

    Another thing is the temperature you mention. A product like Zene Progress ( only requires temperatures of 180 degrees to lock in the Keratin. Which brings me to a final point...

    The Keratin in products like Escova Progressiva - or Brazilian Blowout - actually does permeate the shaft of hairs, entering through the many cracks and fractures in the shaft of each hair. As a water resilient compound, which naturally occurs in the hair, the Keratin then forms a temporarily impermeable coating which 'seals' for around 3-4 months.

    More info on Keratin hair straightening at my blog -

  5. dr ali syed also has info on this very intresting what i dont get is most people that do this are doing it cus they are trying to get rid of the relaxer but surely this is worse for your overall health than a relaxer anyday?

  6. Hi, this is an article I wrote on the subject, needs some updating, though:

  7. My cousin has done this treament over the last 18 months and her 4b hair seems to be thriving. She is retaining length like never before. It makes me wonder if the keratin is actually strengthening her hair. Her hair is not straight at all. It looks like a blowout but it is much more manageable now. She wears natural styles and still avoid heat in btwn treatmenys.

  8. Has anyone had a lab test on the Zene Progress to confirm what level of formaldehyde/Aldehyde/other active ingredient of same family is comprised in this formulation?

  9. Thank you so much. I am a biochemist, and as soon as I heard people telling me they straighten their hair with protein, I said, something is not right and I could not find anything on it as well. Dr.Charlee B told me about your blog and i love it.

    From one sista scientist to another-great job!

    1. Aww thanks Danyell - it is a small world, I did an article with Charlee :)

  10. Not all BKTs are advertised as 'straighteners' nor do they all require up to 450F/230C of heat. I have been using a Brazilian brand and it works as a frizz reducer. My hair looks and feels very strong, and my natural curls return without a problem. The importance lies in doing your research and knowing what the ingredients do. Also, the term BKT has been used a sort of umbrella term for many different product formulations. You have to study the individual products!

  11. Thanks so much for your post. In my group of natural sisterfriends, one was contemplating this treatment. I just so happened upon this and sent it to her immediately. I absolutely LOVE reading your posts because of how you explain things and then give an even more relatable example. I hope you are a teacher or professor of some sort because you are good at relaying info! I also appreciate your taking a stance on something that is unequivocably bad for our hair!

    1. You are welcome, thanks for the compliments.

  12. Thank you for putting this up. Someone had suggest that I try the BKT to straighten my hair & get rid of frizz. But I didn't get to do it because another friend mentioned that she'd heard something in the lines BKT causing cancer. I'm glad I came across this article. It's a lot better than any anecdotal stuff I've heard so far. I just recently came across your site & I have to say it's the most informative site on hair that I've come across.


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