Asparagus contains amino acids

Amino Acids for Hair Growth | 2019 Guide

Amino acids are often described as ‘the building blocks of protein.’ Around one fifth of the human body is made up of protein, which is an essential component of almost all of its biological processes (1).

It makes sense, then, that insufficient intake (or poor absorption) can lead to deficits which impact various processes. This includes a ‘non-essential’ process – hair growth.

In this article, I’ll introduce amino acids and the important role they play in hair synthesis and growth. I’ll then outline a variety of amino acids – including the four that are most essential to keratin production – as well as discuss a few ways you can get more of these essential amino acids into your diet.

An Introduction to Amino Acids

In simple terms, amino acids can be described as organic compounds made up of even smaller compounds known as amines (2).

Amines are made up of a lone atom of nitrogen and a non-bonding pair of valence electrons, which together form the chemical bond of the amine.

The other chemical compound forming amino acids is carboxylic acid, plus the side chain chemical group which gives each different amino acid its individual properties.

Amino acids make up a large proportion of our tissue and muscles, and give cells their particular structure. They are essential to use for storing nutrients and facilitating their movement around the body.

This means that they play an essential role in healing damaged tissue, skin, bones, and hair (3).

The importance of amino acids to our survival is reinforced against a backdrop of the industrialization of society and its consequences for human health.

The majority of people in the world now live in urban environments which are affected by pollution caused by the burning of fossil fuels. These people consume heavily processed foods, including meat from hormone-fed cattle and heavily-fertilized agricultural produce.

They often also live in a culture which promotes the regular consumption of alcohol and smoking of tobacco.

All of these factors reduce the capability of our bodies to fully absorb the nutrients we eat. Just as serious is the actual processing of modern junk food: microwaveable, canned, and frozen products which have lost a good part of the nutrients we need from them – becoming, in effect simply a supply of ‘empty calories.’

All of this has led to a spike, particularly among older people, in diseases and health issues – at the root caused by the body’s inability to absorb enough vitamins, minerals, and amino acids.

These problems include unwanted weight gain, erectile disorders, hypertension, sleep disorders, and even hair loss.

How Can Amino Acids Improve Hair Growth?

Hair is mostly made up of protein and melanin. In fact, around 88% of your hair is made up of one particular protein – keratin (4).

This protein requires four different types of amino acid to be produced by the body. They are cysteine, arginine, lysine, and methionine.

The structure of keratin

All of these amino acids are usually sourced from our diet, but the latter two must always be present in our diet in order to facilitate the body’s production of keratin (5).

Perhaps it should not some as a surprise that poor nutrition can lead to hair loss (6). During deficits of any vital nutrients, our bodies allocate all of the available amounts to the functions which are essential to sustaining life.

As hair production and growth is not fundamental to our immediate survival, these nutrients are diverted away from hair follicles, causing reduced hair production and death of the follicle.

When this happens at a less dramatic level, the reduction in hair production and subsequent loss of hair is only noticeable over long periods of time, i.e. years rather than weeks. Initial indications of an amino acid deficiency in hair production include dull and vapid hair growth.

At present, the effects of amino acid on hair growth are under study from various viewpoints. Initial results from various tests have shown that certain amino acid mixtures, when ingested, can significantly increase the rate of hair growth over periods as short as four weeks.

Such encouraging findings have prompted further study into the effect of amino acids on various hair and skin-related diseases.

The Different Types Of Amino Acids

There are around 250 different known types of amino acid, of which there are 20 which occur in the human body. Of these, a small number are associated with hair growth.


Arginine is an important amino acid which helps to produce keratin (7). It helps improve the function of the body’s immune system, which is an important factor in protecting against autoimmune diseases which affect the hair, such as androgenic alopecia (8).

Arginine may also play a vasodilatory role in ensuring that the follicle is well supplied with blood and nutrients from its supply capillary, through the production of nitric oxide, which triggers the dilation of blood vessels (9).

It is also associated, along with other amino acids, in the repair of damaged tissue.

Without arginine, this process can suffer with reduced hair growth (or hair loss) as a further consequence. Thus, those with underlying health issues need to ensure they absorb an adequate amount of arginine in order to facilitate the treatment of hair loss.


Cystine makes up about one-fourth of the keratin protein and, as such, is a crucial amino acid when it comes to hair growth (10).

Cystine is made up of two cysteine molecules formed together. As such, the close link between these two amino acids (with cystine being the more stable oxidized form) is obvious.

This amino acid has been shown by various studies to reduce the symptoms of alopecia (11). It is also important for the production of glutathione – an antioxidant which protects hair follicles from oxidative stress (12).

While this amino acid is naturally produced by the body, it can help to ensure that it is present in your diet in order to reduce the risk of any deficiency.


Methionine plays an important part in the synthesis of procollagen, which is necessary to form collagen, another amino acid which strengthens the hair shaft (13). It is essential to the integrity of the basic structure of skin, nails and especially hair.

This amino acid is also another antioxidant which has been shown to reduce hair loss. Studies also suggest that it can help slow the thinning and graying of hair. As it isn’t produced by the body, it is important to make sure your diet contains a good amount of methionine.


Lysine is another amino acid which helps stimulate the production of collagen (14). Hair follicles need lysine in order to grow hair properly.


If you haven’t guessed by now, collagen is a major component of a healthy hair strand. And glycine is another amino acid that helps to produce collagen (15).

But aside from this benefit, glycine also plays an important role in the central nervous system, meaning that its presence reduces the possibility of hair loss associated with nerve disorders (16). It is naturally produced by the body, but should also be found in a balanced diet.


Proline is important in the production of collagen, and also protects muscle tissue (17, 18).

Its other health benefits include wound healing, antioxidative reactions, and immune responses (19).


As with the other amino acids on this list, glutamine is produced naturally by the body. In fact, it’s the most abundant amino acid found within the body (20). However, production decreases as the body gets older.

Glutamine plays a role in the immune system, but by middle age is produced in quantities too small to effectively do so (21). By absorbing this amino acid from our food supply, we can help to reinforce the body’s slowing production.

The Best Sources Of Amino Acids For Hair

The good news is that there is a wide variety of amino acid-rich food sources which we can use to ensure our bodies absorb enough to promote healthy hair (22).

  • Good sources of arginine include nuts, sunflower seeds, pumpkin seeds, granola, soybeans, chickpeas, sesame seed oil, chicken, beef, fish, and dairy products (23).
  • Cysteine can be found in good quantities in whole grains, broccoli, legumes, pork, chicken, and dairy products.
  • Food sources which include methionine are nuts, zucchini, broccoli, eggs, and fish (24).
  • Lysine is commonly found in pulses, nuts, legumes, red meat, chicken, dairy products, and fish such as salmon, cod, and sardines (25).
  • Glycine is found in various fruits such as kiwi fruit and bananas. It is also found in kale, beans, cabbage, spinach, soybeans, dairy products, both red and white meat, and fish (26).
  • The best sources of proline are soybeans, legumes, spinach, broccoli, beans, avocado, asparagus, eggs, dairy products, and both red and white meat.

It is important to source these amino acids in natural, unprocessed food. A frozen, microwaveable meal with various vegetables, fish, or meat won’t contain anywhere near the variety and quantity of nutrients as the same meal prepared from fresh ingredients.

The less processed the food you consume, the more you benefit from it nutritionally.

Are Amino Acid Supplements Worthwhile?

Amino acid supplements are popular with those who fear they may not be able to absorb an adequate amount of amino acids from their diet. There are many examples of amino acid supplements having been shown to have a positive effect in reducing hair loss.

Cystine supplements, for example, has been shown to be effective in the treatment of androgenic alopecia in women when taken together with millet seed extract (which contains silicon – a substance which is thought to stimulate hair growth) and vitamin B5 (pantothenic acid) (27).

The German study focused on a group of women who took a 400mg preparation of the three ingredients over three months. The researchers utilized phototrichograms to measure anagen hair rate.

The goal was to see whether supplementation would increase anagen hair rate from abnormal (<80%) to normal (>85%) after three months and at their final visit (six months).

As the results showed, the women in the active supplementation group reached the desired endpoint while those in the placebo group did not. As such, the researchers concluded that cystine supplementation shows a positive relationship between the treatment and reduced effects of alopecia.

Are There Any Side Effects Of Amino Acids?

Amino acids are not commonly associated with side effects, but there may be cases where absorption of too much of a particular compound may produce unexpected results.

Despite the low risk, it is important to know that certain conditions can be worsened by their consumption, and therefore should be avoided by certain groups.

Arginine is considered generally safe, but should be avoided by:

  • Pregnant women
  • Breastfeeding women
  • Asthmatics
  • Children (high doses can lead to death)
  • Sufferers of liver cirrhosis
  • People with guanidinoacetate methyltransferase deficiency
  • Sufferers of herpes
  • Sufferers of hypotension
  • People who have recently had a heart attack
  • Those who have recently had, or are scheduled for surgery

Even in healthy individuals, the amino acid may cause abdominal discomfort (including nausea, diarrhea, abdominal pain, and bloating), gout, allergic response, or airway inflammation (28).

But does arginine interact with medications? It might.

Possible interactions include:

  • Anticoagulants and anti-platelet drugs
  • Blood pressure drugs
  • Blood sugar drugs
  • Isoproterenol
  • Nitrates
  • Water pills
  • Viagra

You should consult with your doctor if you’re on any of these medications, or if you take herbs or other supplements, before you begin arginine supplementation.

Cysteine is also generally considered to be safe, but should be avoided by:

  • Pregnant women
  • Breastfeeding women
  • Asthmatics
  • Hemophiliacs
  • Those who have recently had, or are scheduled for surgery

The most common side effect of increased consumption or supplementation is nausea, but you should be aware that cysteine can trigger false positives in the nitroprusside test for ketone bodies used for diabetes (29).

Cysteine may also negatively interact with insulin and Monosodium Glutamate (MSG), so speak with your physician prior to supplementation.

Methionine is also generally considered to be safe in small amounts. Consuming large amounts in your diet can cause death, and it should be avoided by (30):

  1. Children (when administered intravenously)
  2. Pregnant women
  3. Breastfeeding women
  4. People with acidosis
  5. People with atherosclerosis
  6. People with liver cirrhosis
  7. People with hepatitis
  8. People with schizophrenia
  9. People with Parkinson’s

Similar to the other amino acids mentioned, supplementation can cause gas/bloating and general abdominal discomfort (31).

In Conclusion

It is clear that amino acids play an essential role in hair growth, in the production of keratin and collagen, protecting the hair follicle, and helping its supply of blood and nutrients.

It’s also evident that we must source a number of these amino acids in our diet, through food or supplements, in order to reduce hair loss and stimulate new growth. But even further, we can avoid lifestyle choices which reduce the absorption of amino acids. These include avoiding polluted air, smoking, alcohol consumption, and highly processed food.

And while this may not be the root cause of your hair loss, there’s no doubt that improved amino acid intake and absorption will benefit your scalp, hair, and overall health.

Do you have any questions about amino acids? Let me know down below!

Leave a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.