The Building Blocks Of Hair: Essential Amino Acids The Hair Needs That The Body Cannot Produce

In this age of busy and highly connected people, it is sometimes easy to forget about proper hair care. We often make quick judgments about a product we should use based on how it looks or if our friend uses it without considering whether it provides the most essential and nourishing components of hair: amino acids. Amino acids are typically referred to as the building blocks of protein, and since hair is mainly composed of protein, they are the most useful parts of an effective hair care routine. According to the Milady Standard Cosmetology book, bodies use 20 amino acids, and out of those 20, only 11 are non-essential because they are produced by the body. In fact, about 8 of those essential amino acids, which are not produced by the body, help create hair fibers. Of the 8 essential amino acids, the most essential to look for in products are threonine, leucine, valine, arginine, and isoleucine. Since they are found in larger percentages of the hair fiber, they need to be replenished frequently. This is why products containing these essential amino acids are a necessity for any standard hair care routine.


Threonine makes up about 6.9% of a typical hair fiber. According to the Environmental Working Group guide, it is typically used in products made for hair conditioning and straightening, due to its strengthening properties. When surveying the ingredients list of a potentially useful hair care product, look out for threonine under other names like L-Threonine, DL-Threonine, and 2-amino-3-hydroxybutyric-acid.


Leucine, also known as L-leucine and L-norvaline, represents 6.1% of hair fibers. It is typically used for conditioning hair and is mostly found in amino acid-enriched conditioner treatments. It works together with valine and isoleucine to form branched-chain amino acids (BCAA), which helps to fortify hair follicles and possibly promotes hair growth. Valine and isoleucine make up 5.9% and 2.7% of hair fibers, respectively, and are found in conditioner products.


Arginine is found in 5.6% of hair fibers, and also shows up in products' ingredients lists as pentanoic acid and L-arginine. It is used in enriched conditioners and other hair products because of its ability to "open" the potassium channels of the cells, which helps increase blood flow to the root of the hair. This leads to longer, healthier hair.

On your next hair care product search, consider looking for an amino acid-enriched conditioner to your shopping cart. 

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