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Is Protein Sensitivity a Thing?

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Verna Meachum

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What is protein sensitivity of hair? How can hair be protein sensitive? Have you ever heard that question before?

Yes, protein sensitivity is a real thing. Due to consumer awareness, this issue has been raised, and the fact is, it requires our attention because many suffer from this problem. Today, I’ll explain this all to you and the science behind it.


Is My Hair Protein Sensitive?

Here are some symptoms that may indicate your hair may be protein sensitive:

  • If you find that your hair is hard, rough, and stiff, even though you’re using good quality hair care products
  • Regularly visit the salon for hair care treatment
  • You’ve been using emollients, and/or natural oils/butters, but to no avail- your hair is still hard, stiff and even breaks upon bending

All that effort and the money you paid didn’t do a thing because your hair is still unhealthy, dull, and difficult to style and manage; this all means that something serious is going on with your hair. So, how can you verify and confirm that your hair is protein sensitive? It’s actually easy and requires a very simple test.

How To Test Protein Sensitivity?

All you need to do is;

  • Take a few fibers of your hair (always choose from back underneath section for a test).
  • Moisten the hairs with few drops of water and use whatever material you use to remove any excess water
  • Apply a small amount of well-known protein product from the market. Alternatively, you can purchase proteins extracts online easily, or you can use raw egg white or plain white yogurt
  • Leave it on hair for 5 minutes
  • Rinse off, and dry your hair with whatever material you usually use (i.e. microfiber tower, old t-shirt)
  • Feel your hair, if you find it hard, stiff, and even breaking, your hair is probably protein sensitive

Why is My Hair Protein Sensitive? What is Happening to My Hair?

Hair is a protein by nature, and this protein is called keratin. The structure of keratin is helical, where two strands of protein chains are bonded together through various bonds. To understand the mechanical stiffness of hair as a result of protein application, we need to understand the chemical bonding inside keratin.

Salt Bonds: This bonding involves oppositely charged chemical groups of two peptides (protein) chains. These bonds can be broken by pH changes in the hair, in both the acid or alkaline direction. Readjusting the hair’s pH will reform and stabilize these bonds.

Disulfide Bonds: This is the most important chemical bond present in hair structure and is responsible for the mechanical strength of hair. These bonds cannot be broken by water or heat manipulation. Only chemical agents can break these bonds, and once these bonds are broken, they cannot be reformed back again. It is the main site of action for chemical treatments for permanent hair reshaping and styling e.g., perming, hair straightening, and relaxing. Under alkaline conditions, disulfide linkages are converted to lanthionine bonds resulting in a permanent chemical change, a process generally used in permanent hair straightening. The more disulfide bonds that occur in the fiber, the curlier, and kinkier the hair (i.e. 4 type hair pattern). The higher in porosity your hair is, the weaker and/or fewer disulfide bonds are. The lower in porosity your hair is, the more and/or tighter the disulfide bonds are.

Hydrogen Bonding: These are the most flexible bonds that are easily broken in the presence of water. When the hair is wet during cleansing and shampooing or in the presence of high humidity, the water molecules introduced to hair move in and break up these hydrogen bonds. The good thing is, they are easily reformed back. Hydrogen bonds allow the hair to change shape temporarily and produces a strong hold. (i.e., wet setting, roller sets, twist outs). This greatly influences hair styling and style retention and also explains high frizz under high humidity conditions.

Protein treatments are designed to interact strongly with these chemical bonds. Proteins may act or react with hair via two strategies. Small protein molecules penetrate hair via gaps/holes of the cuticles and firmly engage inside there with different chemical groups. While large protein molecules perform a coating, forming a strong film along the hair shaft. Here, the protein sensitivity of your hair could be due to the following two reasons:

Wrong protein used for your hair:

All of us have different nature and quality of hair fibers. Some of us have our hair chemically altered, either by perms, relaxers or oxidative coloring. These chemical treatments leave hair highly porous with gaps/holes in the cuticle and cortex. For this type of hair, if we use large protein molecules, they may not be able to penetrate and only get deposited at the hair’s surface, leaving inner empty spaces still empty. In simple terms, you are using the wrong protein at the wrong time. So, what do we need to do? We need small protein molecules that penetrate the hair and fill the gaps. Proteins with incorrect molecular size and weight may just deposit on the surface and leave hair more stiff and hardened.

Protein overload or buildup

The other possibility for your protein sensitivity is potentially due to overloading and buildup of protein molecules at the hair’s surface. This has also been observed for higher molecular synthetic polymers. This increases the weight on the hair shaft, and hair becomes dull, limp, and challenging to manage. With repeated applications of proteins, this buildup continues and eventually, hair gets hardened.

Let’s Prevent & Resolve the Protein Sensitivity Problem

Our hair and/or scalp can have a sensitivity to protein, and the clue would be in the reaction to it during or after the application. The only problem is since products have so many ingredients, how do you know what is causing the problem? It could well be a combination of protein with other ingredients that you have a sensitivity to rather than the protein itself, but the only way to determine what exactly is causing the problem is through trial and error.

Everyone’s hair is unique and will react differently. And what makes it more complicated is that not all proteins are the same. Before declaring yourself protein sensitive, think about the types of protein you apply to your hair, how often, and the present condition of your hair. There are various types of proteins extracted from various sources e.g. milk, oats, wheat, rice, quinoa, soy, keratin, etc. they are different in molecular weight, size and chemical composition of amino acids.

The table below describes it for some of the proteins used in hair care products.

Table 1: Amino acid profile (in percentage) of various proteins. The data is an average of multiple data sets. 1-2

The above table tells us the amino acid profile for various proteins (in percentage). As a tip, proteins that contain high levels of glutamic and aspartic acids are better for hair conditioning, moisturizing, and hydration (for example, wheat and oat protein). Human hair keratin is rich in sulfur-containing cystine, which provides hair strengthening and improves its tensile properties.

Very important: Read, read, read ingredient labels CAREFULLY. I can’t stress this enough. Keep track of which products your hair responds to, whether positively or negatively. You know your hair the best.

Things to keep in mind: Products that have protein listed among the first 5 – 6 ingredients have a higher amount of proteins. Some of us, even those who do a lot to our curls, know we need to strengthen our hair and can go overboard on the protein. It’s not so much “sensitivity,” it’s just that we need to cut back on the frequency and add more moisture. So, in such a case, do not use protein products regularly. Once a month or every two weeks is more than enough. Also, it could be that your hair may benefit more from a lower amount of protein. Keep in mind that applying three products could mean you’ve put ten or more ingredients on your strands. Thus, it’s very important to know ingredients, but the product combo and amount of product matter too.

Water, water & water: Wash your hair with anti-residue shampoo or co-wash if you follow the curly girl method. This is important to remove protein and any polymeric buildups. However, it does not necessarily mean you need a sulfate shampoo, a good mild cleanser will do a great job. This cleansing must be followed by emollients and a moisturizing treatment to provide much-needed moisture to your hair.

Tip: Strong protein treatments, must always be followed by a moisturizing treatment, to give the hair flexibility and manageability.


Protein treatments are essential for our hair because they strengthen and repair the hair shaft and enhance the ability to absorb and maintain moisture. Water molecules bind easily to a good protein structure within the hair shaft; hence, it’s imperative to maintain a protein/moisture balance. However, we need to know our hair and what it needs. Applying every other protein product we find on the market is not the solution.

Excess of everything is not always a good thing, as an excess of proteins may actually leave your hair unhealthy. Choose the right protein that suits your hair and gives you the control over your hair styling and manageability. It’s all a matter of knowing and paying attention to what your hair needs – always remember to let your hair be your guide!


1. Neudahl, G. A., Proteins for conditioning hair and skin. In Conditioning Agents for Hair and Skin, Schueller, R.; Romanowski, P., Eds. Taylor & Francis: 1999; pp 139-166.

2. Escuredo, O.; Martín, M. I. G.; Moncada, G. W.; Fischer, S.; Hierro, J. M. H., Amino acid profile of the quinoa (Chenopodium quinoa Willd.) using near infrared spectroscopy and chemometric techniques. Journal of Cereal Science 2014, 60 (1), 67-74.

Further reading:

· Zviak, C., The Science of Hair Care. Taylor & Francis: 2005.

· Robbins, C. R., Chemical and physical behavior of human hair. 4th ed.; Springer-Verlag: New York, 2002.

· Corporation, A. P., Hair Care: From Physiology to Formulation. Allured Publishing Corporation: 2008.

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