Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 6/22/2021
You might wonder if amino acids (otherwise known as protein) have something to do with hair loss.
Protein is necessary for muscle growth and strength, so it might make sense that it’s a necessary component for hair growth.
If you’re starting to lose your hair, you’re dealing with a threat to your attractiveness and youth—which doesn’t feel good.
Worse, science has, to a certain extent, confirmed it. Dealing with hair loss hair can be scary, and research shows that you’re not alone in this fear.
According to research published in Dermatologic Surgery, around 16 percent of men aged 18 to 29 already have moderate to extensive hair loss.
And by the time the 40s hit, the amount of men with moderate to extensive hair loss grows to more than 50 percent.
Like many other appearance-related issues, hair loss is a huge industry that’s attracted plenty of treatments built around junk science.
Whether it’s nutritional supplements, herbs, shampoos, exercises or suspect home remedies, the list of bogus products that promise fast hair growth is miles long, with product after product offering endless hype with little in the way of results.
So, where do amino acids fit in? Read on to learn more about the science in detail, and to dig into the following:
Amino acids are crucial to nearly all of your tissue, including your hair. Numerous amino acids are essential for healthy, sustainable hair growth.
Despite this, the chance that your receding hairline or bald spot is caused by an amino acid or protein deficiency is relatively slim.
Although amino acids offer numerous health and physical performance benefits, there’s no convincing scientific evidence that amino acid supplementation or topical amino acid products can improve hair growth in men.
If you’re starting to lose your hair, these will do far more to stop your hair loss and promote regrowth than any over-the-counter supplement.
Amino acids are organic compounds that act as the building blocks of proteins.
When you take in protein from food or supplements, your digestive system breaks it down into amino acids that then create and repair tissue.
In total, there are 22 different amino acids that make up proteins. These amino acids are sorted into three different groups:
Essential amino acids. There are nine essential amino acids, which can’t be produced internally by your body. These amino acids need to be consumed in the form of food or dietary supplements. The nine essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Nonessential amino acids. These amino acids, which are referred to as dispensable amino acids, can be produced inside your body. If you don’t take in these amino acids from your diet, your body can synthesize them using the essential amino acids.
Conditional amino acids. These amino acids usually aren’t essential, but can become so in certain situations. You may need these amino acids in periods of growth or when you’re physically or mentally unwell.
Contrary to what the supplement industry might tell you, you don’t need to eat precise amounts of each amino acid with every meal.
However, it’s important to consume a balanced diet that includes all of the essential amino acids for your general health and wellbeing.
So, what do amino acids actually do? If you paid attention during your childhood biology class, you probably know that proteins, which are made of amino acids, are the “building blocks of life!”
Since we’re all adults now, let’s cut right to the chase: Amino acids play an important role in several processes within your body, including muscle growth, bodily tissue maintenance and the production of certain hormones.
Your body can also use amino acids as an energy source in certain situations, such as when you exercise.
In addition to repairing muscle tissue and providing your body with a source of energy, certain amino acids deliver other benefits:
Neurotransmitter production. The essential amino acid phenylalanine acts as a vital precursor for tyrosine, dopamine, norepinephrine and epinephrine—neurotransmitters that help regulate your mood, cognitive function and behavior.
Skin and connective tissue repair. Threonine, another amino acid, plays a key role in the production of your skin and connective tissue.
Growth hormone production. The amino acid leucine helps to regulate production of growth hormones.
Histamine production. The amino acid histidine is essential for creating histamine—another neurotransmitter your body uses to maintain your sleep-wake cycle, aid in digestion and promote healthy sexual function.
The bottom line is that amino acids are absolutely essential. Without them, your body and all of its proteins—including those that make up your hair—simply won’t be physically possible.
When it comes to hair growth, amino acids are essential. However, this doesn’t mean that you can rely on amino acid supplements to give you a full, flawless head of hair.
"Unlike in the case of the skin, the presence and the role of naturally occurring free amino acids in hair shafts are not known yet," reads a study on the effect of amino acids on hair published in the Journal of Cosmetic Science.
As with a lot of other research, our understanding of the relationship between amino acids and hair growth is like an iceberg.
While there’s a small amount above the water that we can grasp, there’s a lot more uncertainty and unknown information beneath the surface.
Put simply, the things we don’t know about amino acids and hair loss significantly outweigh what we do know.
Like the rest of your body, your hair is packed with amino acids. In your hair, amino acids occur naturally in the form of keratin—the structural protein from which your hair is made.
But amino acids are also produced as a result of protein degradation caused by environmental damage, for example, and not just in keratin when the hair leaves your scalp.
Although plenty of websites and snake oil peddlers may try to convince you otherwise, since there are so many different factors at play, the solution to hair loss isn’t so simple.
In fact, research that definitively links improvements in hair growth to the use of amino acids is lacking in general.
Although there’s real evidence that medications like finasteride and minoxidil can slow or stop hair loss from male pattern baldness, there’s relatively little known in relation to dietary supplements.
Now, which amino acids actually help with hair growth? While research into the effects of amino acids on hair is limited, some studies have found that specific amino acids may offer benefits for the health, strength and continued growth of your hair.
Amino acids account for a large percentage of the chemical structure of your hair. For example, approximately 18 percent of keratin, the structural protein that your hair is built from, consists of the amino acid cysteine.
A few small studies have linked cysteine supplementation to improvements in hair growth:
In a study published in the Journal of Applied Cosmetology, a small group of volunteers who took a cysteine supplement for 50 weeks experienced a 50 percent increase in hair growth.However, this study was small in size, with just 48 participants, of whom only 12 took the cysteine supplement.
In a study published in 2007, researchers found that a dietary supplement containing L-cystine (an oxidized form of cysteine) and other active ingredients improved hair growth in women with telogen effluvium hair shedding.While this study is interesting, it’s important to note that the supplement included several active ingredients and that none of the participants suffered from pattern hair loss.
Another amino acid, lysine, has been researched as a possible treatment for hair loss. Lysine is an essential amino acid that has a significant impact on hair integrity.
It’s primarily found inside the hair root and helps hair to retain its shape and volume.
When paired with iron, there’s some evidence that women with hair shedding may experience a decrease in shedding with lysine and iron supplementation.
However, this doesn’t mean that lysine can help male pattern baldness, which is caused by the effects of genes and hormones rather than a nutritional deficiency.
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Scientists have spent a large amount of effort looking at the potential effects of amino acids when applied directly to the hair.
Because chemical reactions (like those that happen in the sun or when you color your hair) can deplete proteins and amino acids in the hair, this research has largely focused on the effects of hair products on hair health and integrity, rather than hair loss or growth.
For example, a 2005 study published in the Journal of the American Academy of Dermatology showed that six different amino acids can be lost during hair "weathering," but that some of these amino acids can be reintroduced to hair through topical hair care products.
Topical hair care products containing amino acids, the researchers noted, “had a direct effect on the strength of the hair.”
While this is useful information for people with damaged hair, it’s unlikely that these products will help to treat hair loss unless your hair loss is caused by damage from coloring, heat treatments, sun exposure, or other environmental factors.
While amino acids offer numerous benefits for your wellbeing and can certainly help you to keep your hair strong and healthy, there’s no evidence that they can treat male pattern baldness.
However, there are proven, science-based medications available that can slow, stop and, in some cases, even reverse the effects of male pattern baldness.
Currently, the two most effective options for treating male pattern baldness are the medications finasteride and minoxidil.
Minoxidil is a topical medication that you apply to your scalp. It works by moving your hairs into the anagen, (growth) phase of the hair growth cycle.
It may also increase blood flow to your hair follicles, supplying them with the nutrients required for optimal growth.
Amino acids offer numerous benefits for your health and wellbeing, from building muscle tissue to maintaining your skin, nails and hair.
In rare cases, hair thinning and hair loss may be linked to amino acid deficiencies. However, the majority of cases of hair loss in men are caused by male pattern baldness, which is unrelated to amino acid intake.
Protein deficiency in the United States is very rare and is caused by not consuming enough food in general rather than a simple lack of animal-based protein.
If your hair loss is related to a protein deficiency, the best way to treat it is to change your diet to include more protein-rich foods.
As for male pattern baldness, you can treat and prevent it with science-based medications such as finasteride and minoxidil.