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How Protein Impacts Hair Growth

Adequate protein consumption is not only critical for supporting muscle tissue, but also the growth and health of your hair.

All hair is made of the same keratin and amino acids,” Tiche Florence, certified trichologist says. She says that structurally, amino acids are the building blocks of polypeptides and proteins and are essential for physical development, necessary for other functions of the body such as hair and nail growth. “Keratin, the protein that makes up 95% of hair is made up of over 18 types of amino acids.”

While the hair fibers and scalp receive benefits from hair care products formulated with amino acids. To truly impact the health of scalp and hair, the body must have the necessary essential and non-essential amino acids. This can be achieved through a diet that provides all 20 amino acids or supported through a dietary supplement.

In this article, we will first look at the biology and hair structure, understand what is an “essential” vs “non-essential” amino acids, what happens to your hair when there is a protein deficiency, and how much protein you should be consuming to nourish your hair follicles for strong roots and hair.

Biology of Protein in Hair Structure

There are two types of protein present in your hair – one in the strands themselves, and another – at the follicle, that is the root of your hair.

Protein in Hair Strands

As mentioned your hair strands consist of a protein called “keratin”, and keratin consists of amino acids – organic compounds which are the building blocks of proteins and which your body breaks down from the protein you consume. Amino acids are needed for vital processes such as cell building, muscle growth and repair, wound healing, regulation of blood sugar levels, energy production, immune function, the synthesis of hormones and the list goes on.

When taken in through diet or supplements, your body identifies areas of amino acid shortage and decides which areas need a top up. It may not always go to your hair, even though it may be your preferred area of protein focus.

Protein in Your Hair Follicles

Hair follicles are the small, pocket-like holes in our skin from which our hair grows. The average human has about 100,000 hair follicles on the scalp alone, Hair starts growing at the bottom of a hair follicle. Collagen makes up 70% of your dermis, the middle layer of your skin that contains the root of each individual hair. Since collagen protects the layer of skin that contains hair roots, it helps prevent age-related hair loss and thinning. Collagen also acts as an antioxidant and fights damage caused by free radicals. During the growth stage of hair (anagen), collagen levels increase in the hair follicle and the lining of the hair bulb.

Why Protein is Important to Hair Growth?

Your body uses proteins to build tissue cells — including the cells of your hair, skin and nails. Eighty to eighty-five percent of your hair is composed of the protein keratin. Dietary proteins are composed of amino acids, which are your hair’s building blocks.. Amino acids can be divided into two categories: essential and non-essential. Essential amino acids cannot be synthesized by the body, and so must be obtained through the diet. Non-essential amino acids can also be obtained from food, as well as being manufactured by the body from essential amino acids.

Without sufficient available protein, your hair can become brittle and fall out before it reaches its full length. This is one of the reasons why people with a low-protein diet experience hair loss, and often find their hair will not grow past a certain length.

Let’s look at the difference between an essential vs non-essential amino acid in the context of hair:

  • “Non-essential” amino acids are those that our bodies can produce itself – from other amino acids you consume through food intake or supplements. In hair growth, cysteine is a non-essential amino acid, necessary for construction of hair and providing sulfur to the follicle to improve strength, elasticity and texture. Cysteine is metabolized from methionine – which is an “essential” amino acid. Arginine, supports blood circulation around the hair follicle and supports the growth and health of the hair and the hair follicles themselves.
  • “Essential” amino-acids are those your body can’t naturally produce and must be provided through dietary intake. Lysine, a restorative amino acid that supports collagen production; and methionine, which aids in making pre-collagen, which becomes collagen.

Shortage of Protein can Stunt Hair Growth

In case of an on-going protein deficiency, the body curbs amino acids sent for hair growth and hair follicles, in favor of life-supporting functions: such as muscular-skeletal and cardiovascular systems. This is also commonly experienced in the case of hormonal imbalance or periods of high stress, This in turn leads to poor hair health, hair breakage, stunted hair growth and hair loss.

While short-term protein shortages are typically manageable by the body, a balanced diet supplemented with vitamins and amino acids is recommended to support the long-term health of the hair and to help reduce the risk of hair loss.

Additional nutrients and vitamins (e.g. vitamin B1) are essential to effective protein metabolism and the breakdown to the amino acids your hair needs. Because the nutrient density of our food has decreased dramatically over the last 100 years, dietary intake isn’t al supplementation becomes increasingly important and diet alone would be insufficient for healthy hair growth.

Keratin is the Protein which Makes Up Hair, but what Else?

The hair shaft consists of 3 different types of bonds: hydrogen, salt (saline) and disulphide bonds.

Hydrogen bonds allow our hair to change shape temporarily and produces a flexible hold. Examples include blow dry, curling or straightening your hair with a heat styling tools.

Salt (saline) bonds are responsible for hair’s strength and a consistent percentage of hair’s elasticity. They are created between the positive end of one amino acid chain and the negative end of another. Which is why they are also known as “ionic” bonds in hair. Like hydrogen bonds, these are also temporary and weaker bonds which also are normally broken by water or heat.

Disulphide bonds are stronger and more permanent, thus requiring strong chemicals to break them. For example in chemical perms a strong chemical – ammonium thioglycolate – is used to break those disulphide bonds that leads to permanent change in hair structure.

Hair shafts with missing molecules of keratin often lack luster and are prone to breakage, because broken disulphide bonds within the hair shaft weaken the shaft.

What Keratin in Hair is made of?

Keratin is high in Sulphur, the largest component of the disulphide bonds. Sulphur in hair is made up from cysteine, which is replenished through a healthy diet rich in methionine to manufacture it – and some supplementation. Low amounts of methionine, and therefore lack of Sulphur can lead to thinning hair and especially hair breakage, and – as a result of it – split ends.

Disulphide bonds are further nourished by natural hair products, gentle styling and hair care methods.

Food Sources of Protein for Hair

The best sources of protein include fish, eggs, red meat, poultry, cheese, beans, quinoa, tofu, seitan, legumes and nuts. Be wary of cheese, though: it can exacerbate eczema and dandruff in some people, and also takes over two hours to digest.


Cysteine is, inarguably, the most crucial of amino acids for hair growth. It establishes disulphide bonds in hair. In a number of clinical studies, diets supplemented with cysteine reduced hair loss in subjects over the period of 6 months.

Best food sources of Cysteine: Your body can manufacture cysteine from methionine, an essential amino acid. The major dietary sources of methionine include eggs, beef liver, broccoli, wheat germ, Brussels sprouts, and some dairy products like milk and yogurt. Daily RDA of methionine for an adult of 68kg weight is 1.1g.

Glycine and Collagen

Glycine is one of the main building blocks of collagen, the most abundant protein in the body. Collagen is important for hair growth because it lines the hair follicle supporting the anagen (growth) stage of your hair.

While ingesting collagen is an effective method to top up collagen levels, supplementing your diet with the building blocks including: vitamin C and glycine – can provide strength for your muscles, skin, cartilage, blood, bones, ligaments – and hair. Another way to manufacture collagen locally on your scalp is through dermarolling.

Best food sources of Glycine: since glycine is a non-essential amino acid, your body can manufacture it. To supply the building blocks for it, consume foods dairy products – greek yogurt, certain cheeses (parmesan, mozzarella), seeds – especially sesame seeds, lean turkey, soybeans. Daily RDA of glycine is 2-5g.

Keratin Treatments

Keratin treatments are semi-permanent hair straightening treatments that smooth and add shine to frizzy hair, while keeping freshly-colored hair vibrant. Keratin is a structural protein found in our hair, skin, and nails. It’s also commonly found in styling products to help strengthen hair—but the term keratin treatment is actually a misnomer.

How the treatments work is not through the use of keratin, but rather to make hair straighter, a solution containing a formaldehyde derivative or (the much safer) glyoxylic acid is worked through the hair to change the curl pattern and reseal the hair in a straighter position. The solution is then blow-dried and sealed with a flat iron locking the hair into this straighter position for anywhere from three to six months. Keratin smoothing treatments work well on most hair types, and are ideal for anyone who wants to reduce frizz, boost shine, or cut out blow-drying or straightening their hair on a regular basis.

Our smoothing treatment is a 100% formaldehyde free, next generation smoothing system that uses the latest advances in science and the finest ingredients that gets your hair to its ideal, most beautiful condition restoring natural shine for overall manageable, healthier hair.

Request a Hair Consultation

To learn more about hair loss / restoration solutions including Hairskeen, SCHEDULE A HAIR LOSS CONSULTATION with our Columbus Ohio Hair Loss Specialists.

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