Role of protein and amino acids in hair growth

By December 15, 2019July 16th, 2020Biology, Food for thought

Good news for the body builders, since consuming protein is not only great for the muscles, but also – for the hair growth. For the mere mortals amongst us we might need to take a close look at our diet and supplements. But first, let’s dive into the biology of it all.

Biology of protein in hair structure

Your hair consists of protein, called “keratin”, which in turn consists of amino acids – organic compounds which your body breaks down from the consumption of protein. Your body needs to identify areas of amino acid shortage and decide which ones that need a top up. Lower protein levels can lead to breakage in hair and slow hair growth simply because your body lacks those building blocks.

Why protein is important to hair growth?

Your hair consists of 85-90% keratin – a complex protein that also makes up majority of your skin and nails. In turn, keratin is built up by 18 essential and non-essential acids.

An amino acid being “essential” means our body doesn’t naturally produce it, therefore it needs external injection in the form of supplements or food. If protein levels are too low, the protein goes to more essential functions: supporting muscular-skeletal and cardiovascular function, rather than hair growth. Thus, in case of chronic protein deficiency, body neglects scalp and hair growth. While short-term protein shortages are acceptable, a balanced diet supplemented with vitamins and amino acids puts you on a sustainable path securing long-term hair health.

A word on keratin

Hair shaft consists of 3 different types of bonds: hydrogen, salt (saline) and disulfide bonds. Hydrogen bonding allows our hair to change shape temporarily and produces a flexible hold. Disulfide bonds are stronger and more permanent, thus requiring strong chemicals to break them, such as ammonium thioglycolate – a chemical used in perms. Keratin is high in sulfur and the biggest component of the disulfide bonds. It can be built through a healthy diet, and nourished by natural hair care products, gentle styling and hair care methods. The hair shafts with missing molecules of keratin often lack lustre and are prone to breakage, as the broken disulfide bonds within the hair shaft weaken the shaft.

Protein digestion and hair growth 

Your digestive system breaks down proteins into amino acids that then get diverted into liver to produce more protein in the form that your body requires. Whether it is muscle tissue or keratin structures in hair, your body needs to consume enough protein in order to supply necessary building blocks. Since some key amino acids are not directly produced by your body, it helps to supplement with a balanced nutrition rich with amino acids. Taking into the necessary amount of protein (roughly 0.8g per kilo of weight), so that body can regulate itself and decide which type of amino acid it needs to produce – can be a good start.

Plant-based protein sources contain a number of micronutrients and vitamins, that you need to supplement with vitamin B12, vitamin D, the omega-3 fatty acid DHA, iron and zinc. While you can definitely get those from the foods you eat, it helps to take supplements that contain those nutrients. For example to support your iron intake it helps to combine your cooked spinach (naturally rich in iron) with vitamin C-rich broccoli. It also contributes to your uptake of fiber. In future we explore plant-based diet tweaks and supplmentation for hair health.

Let’s look at two groups of kertain-associated proteins rich in the amino acids cysteine and glycine: the building blocks of this critical protein for hair growth.


Cysteine is, inarguably, the most crucial of amino acids for hair growth. It establishes disulfide bridges, a type of bond that plays a fundamental role in the folding and stabilisation of protein structure: including the bonds within the hair shaft. In a number of clinical studies, diets supplemented with cysteine reduced hair loss in subjects over the period of 6 months.

Best sources of Cysteine: The major dietary sources of cysteine include broccoli, wheat germ, Brussels sprouts, and some dairy products like milk and yogurt.

Glycine and collagen

Glycine is one of the main building blocks of collagen, the most abundant protein in your body. While ingesting collagen isn’t the way to top up the levels of collagen in your hair, supplementing your diet with the building blocks: vitamin C and glycine can provide strength for your muscles, skin, hair cartilage, blood, bones and ligaments.

Best Sources Of Glycine: Your body naturally produces glycine, but it can also be supplemented by foods like dairy products, spinach, beans, cabbage, soybeans, and banana.

Keratin treatments

The process of keratin treatment involves artificially adding keratin to the hair shaft. First, it starts with opening the hair cuticle to make it susceptible to the absorption of keratin. Then, it follows with ingesting the hair shaft with keratin and sealing it back for smoothness, manageability and shine. Though this process can visibly “repair” a damaged hair shaft, it often involves using harsh chemicals such as formaldehyde and high temperatures for sealing and therefore cannot be recommended as an on-going way to support hair health. 

As tempting as it this “fix” sounds, a more sustainable way to top up your keratin levels comes from within. Think balanced nutrition with necessary amount of whole proteins supplemented with key aminos: cysteine and glycine as building blocks of keratin within your hair follicle. 

If you want to understand nutrition to support your hair health, here >> you can find out specific foods to eat in order to grow your hair.

Topical proteins

The best support for hair growth needs to combine external and internal methods. As you incorporate more proteins into your diet, you need to look into natural topical solutions available on the market, specifically those focusing on the blood flow to scalp. The Hair Fuel mask helps you regain hair strength and improves hair growth rate, as it focuses right where the growth starts from: the hair follicles and scalp. The formula uses plant-based proteins to help regain hair health. Read more here >>


Organization and expression of hair follicle genes, Journal of Investigative Dermatology (1)

The structure of people’s hair (2)

Effects of the Usage of l-Cysteine (l-Cys) on Human Health (3)

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