All About Amino Acids
November 2, 2024
Remember grade school science class, when you learned about amino acids as the building blocks of protein?
Although protein receives the primary attention as the key nutrient for building muscle, proteins and their building block amino acids are also vital to the growth, repair, and structure of our cells and tissues, including our hair, skin, and nails. Proteins play a role as catalysts for nearly every chemical reaction in the body, and various individual amino acids also serve double duty as hormones and neurotransmitters – chemical messengers that transmit signals between nerve cells.
Today we are going back to basics to explain what amino acids are and the foundational role they play in a wide range of critical functions in the body.
What are amino acids?
Although most people have a basic understanding of the importance of amino acids, let’s dive into the benefits of amino acids a bit deeper and explore the different roles they play in the body. Amino acids are composed of an amino group that contains a single nitrogen molecule that is bound to two hydrogen molecules, plus what is known as a carboxylic acid group (carbon, hydrogen, and two oxygen molecules) – hence the name “amino acid.” A peptide is formed when two or more amino acids are joined together by a peptide bond, and when these amino acids are strung together in a longer chain, they are known as polypeptides. Proteins can be composed of one or many polypeptides.
How many amino acids are there?
Of the hundreds of different amino acids found in nature, there are only about 20 the human body uses to build more than 100,000 unique proteins.1 These amino acids are considered alpha amino acids and they are present in what is known as the L- configuration, hence the “L” in front of their names.
The 20 amino acids used for protein synthesis
The amino acids listed below are foundational to human metabolic processes and can be combined in a variety of ways to build different proteins.
It should be noted that one additional amino acid has been identified as playing a role in the synthesis of human proteins: selenocysteine ‒ often referred to as the 21st amino acid.1
That said, of the 20,000+ protein-encoding genes identified in the human body, only 20 amino acids are universally present in the genetic code.1
Essential vs. non-essential amino acids
Of the 20 foundational amino acids, the body is capable of making 11 of them; these are called non-essential amino acids.
The remaining nine amino acids are called essential amino acids (EAAs) because we must rely exclusively on diet or supplementation to obtain them.
The following make up the complete list of essential amino acids:
Histidine
Isoleucine
Leucine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Because our bodies are not able to manufacture EAAs, it is imperative to get adequate dietary intake to sustain our needs, as well as relying on amino acid supplementsto fill in nutritional gaps.
How to obtain amino acids in the diet
When a food contains all nine EAAs, it is considered a complete protein – sometimes called a “perfect” or “high-quality” protein. Animal products are generally the best source of complete proteins, including lean meat, eggs, poultry, fish, and dairy products.
Although plant proteins from nuts, seeds, beans, and grains are also a great source of amino acids, generally these foods are considered “incomplete” because individually they don’t contain all nine essential amino acids in adequate amounts.
Combining plant foods together is a great way to obtain a “complete” protein. The classic dish of beans and rice, for example – a staple cuisine in many parts of the world – makes a complete protein when consumed together because beans provide an adequate amount of lysine that is often lacking in rice, while rice provides methionine that tends to be lower in beans and other legumes. Although beans and rice together are delicious, essential amino acids do not need to be consumed at the same time or even within the same meal to deliver the nutrition your body needs to thrive; it only matters that all nine essential amino acids are provided consistently in the diet.
Although limited, there are a few plant sources that do deliver all the essential amino acids in sufficient amounts. Vegan sources providing a complete protein include soy products, such as tofu, tempeh, edamame, and miso, as well as the grains buckwheat and quinoa.
Branched-chain amino acids
What do branched-chain amino acids do? Of the nine essential amino acids, three are known as branched-chain amino acids (BCAAs), which are of particular importance for muscle growth and repair, as well as having important influence on the production of various neurotransmitters.2
Among the BCAAs, leucine is considered the most important amino acid for muscle growth, as well as maintenance of lean muscle mass; however, evidence indicates that any significant increase in muscle synthesis depends on an adequate intake and availability of all nine essential amino acids.3
Although many supplement companies make a stand-alone BCAA powder, a formulation that features a comprehensive combination of branched chain amino acids paired with the other essential amino acids, such as Thorne’s Amino Complex, more holistically supports athletic performance and lean muscle mass.*
What do amino acids do for the body?
The 20 amino acids listed above provide a source of energy, support healthy digestive function and immune response, and are integral to the body’s production of various enzymes, hormones, and neurotransmitters. Sulfur-containing amino acids, such as methionine and cysteine, serve important functions in the body’s detoxification processes and antioxidant activity.4 The amino acids, cysteine, glutamine, and glycine are the building blocks for creating glutathione, one of the body’s most important antioxidants and a critical nutrient for supporting the liver’s detoxification from environmental toxins.*
Although each of these 20 amino acids plays a vital role in our metabolic processes, there are a couple notable amino acids that deserve some extra mention.
Which amino acid is the most abundant in the body?
L-glutamine is the most prevalent amino acid in the bloodstream and is found in high concentrations in the gastrointestinal tract. Glutamine is the primary source of fuel for the cells that line the small intestine. This amino acid also plays an important role in the integrity of the gut lining, supporting optimal gut barrier function and improving gut permeability.*
Glutamine has also been found to be beneficial in supporting healing following injury or surgery because it supports muscle cell repair and immune function.* Although glutamine is not an essential amino, conditions of chronic stress, as well as prolonged or intense exercise, can take a toll on the blood level of this important amino acid, particularly for athletes with limited opportunities for adequate recovery between workouts. Evidence indicates, however, that glutamine supplementation can offset many of these challenges.*
Thorne offers L-Glutamine in a convenient capsule formulation. For the competitive athlete, Thorne’s L-Glutamine Powder is a flavorless formula that dissolves in water and is also NSF Certified for Sport®.
Glycine is one of the most important inhibitory neurotransmitters in the central nervous system and supports a healthy stress response. Research has shown that glycine supplementation helps improve memory for individuals who are experiencing disrupted sleep from jet lag or shift work. Glycine is also one of three amino acids needed to produce creatine, which supplies energy to muscle and nerve cells, and it plays a key role in liver detoxification by enhancing glutathione levels.*
L-lysine is an essential amino acid that serves as an important building block in the formation of collagen, which supports the structural components of skin, bones, and muscle. Lysine also plays an important role in the body for immune function and wound healing, with evidence pointing to its potential benefit for maintaining healthy gum and lip tissue.*
The amino acid tryptophan is an essential precursor to 5-hydroxytryptophan, which in turn is a precursor to serotonin – a hormone neurotransmitter that plays a key role in mood regulation and feelings of satisfaction and well-being.*
L-tyrosine supports the body’s production of thyroid hormones, as well as the production of dopamine, another key neurotransmitter involved in mood regulation.
Conditionally essential amino acids
To make matters slightly more confusing, besides the nine essential amino acids, there are also several amino acids that are considered to be “conditionally essential,” meaning that although our bodies are capable of synthesizing them in most instances, certain circumstances can hinder this process and increase the need for dietary or supplemental intake. Injury, illness, stress, pregnancy, and aging can all factor into an impaired ability to manufacture certain conditionally essentially amino acids.4
If liver function is impaired, for example, then amino acids like cysteine, tyrosine, or arginine can become essential to obtain from the diet due to impaired conversion from precursor amino acids.4 Genetics can also play a roll. For example, the inability to convert phenylalanine to tyrosine is a genetic condition called phenylketonuria (PKU), which is tested for at birth and if left untreated (treatment involves avoiding phenylalanine-containing foods) can result in brain damage. This inadequate production of the specific enzyme needed to convert phenylalanine to L-tyrosine is another circumstance requiring dietary tyrosine.5
Because the synthesis of conditionally essential amino acids also relies on adequate intake of the essential amino acids, insufficient intake of any of the EAAs can create a downstream effect. Cysteine and tyrosine are often considered the most important conditionally essential amino acids because their intake accounts for some of the requirements for methionine and phenylalanine, respectively.4 The following are considered conditionally essential amino acids:
Non-protein amino acids
Although only 20 amino acids are specifically coded to build proteins, there are many more non-protein amino acids that provide unique benefits in the body and deserve consideration for inclusion in a nutritional supplement regimen.
Taurine, for example, is not used for protein synthesis and is therefore not considered to be one of the core 20 amino acids discussed above. Taurine, however, is ubiquitous in human cells – it is found throughout the body in numerous tissues, including skeletal muscle, the brain, and the heart.6 Taurine is the most abundant amino acid in the heart and promotes the production of nitric oxide, which benefits blood flow and supports healthy blood pressure. Taurine is also involved in the formation of bile in the liver, which facilitates fat digestion and supports the detoxification of environmental toxins.*
Although taurine is considered a conditionally essential amino acid, there is some debate regarding whether we can adequately synthesize enough to meet our body’s demand or whether we do, in fact, rely on taurine from our diet.5 Although taurine is found in many animal foods, including meat and dairy products, considering its wide variety of important roles in the body, a taurine supplement might be beneficial for many individuals, especially vegetarians.
L-citrulline is an amino acid the body uses to make L-arginine, which is also needed for the production of nitric oxide. Citrulline is found in high concentrations in watermelon juice, and there is evidence that it could have a beneficial cardiometabolic benefit, although its primary known function is to recycle and maintain the level of arginine.7
L-theanine, a type of amino acid found in tea, particularly green and white teas, promotes sleep quality by enhancing the alpha-brain waves that support deep relaxation. Although it is not used to make protein, theanine has many health-promoting benefits, such as antioxidant activity and supporting the stress response and healthy sleep cycles.8 Thorne’s Theanine supplement can enhance the production of the neurotransmitters dopamine and serotonin and promote a relaxed, yet alert state of mind.*
Beta-alanine is another amino acid worth mentioning because it is used extensively as an ergogenic aid. Beta-alanine, a derivative of alanine, specifically helps in the production of carnosine, a compound that supports muscle endurance capacity during workouts. Thorne’s Beta Alanine-SR is a sustained-release tablet that provides long-lasting benefits while minimizing side effects.*
L-Carnitine is an amino acid that supports the metabolism of fat and fat’s conversion into cellular energy via the mitochondria, the powerhouses of all cells. Carnitine also supports athletic performance and helps maintain healthy levels of cholesterol and triglycerides.*
Creatine is often considered to be a key amino acid for supporting athletic performance because it supports cellular energy production, enhances energy output, promotes the growth of lean body mass, and benefits cognitive function.* The amino acids glycine, arginine, and methionine are needed to make creatine, and because creatine is primarily found in meat, eggs, and fish, vegetarians can benefit from its supplementation.
What is the value of taking an amino acid supplement?
Although there are many amino acid supplements on the market, the perfect aminos for you will be the ones you love to take and are formulated to support your unique health goals.
Why are supplements a good choice?
Amino acids are foundational to human health. Because the body is only capable of making 11 of the 20 foundational amino acids, supplements can be a good, convenient source of the nine essential amino acids. In addition, a special, non-protein-synthesizing amino acid like creatine or taurine might provide certain health benefits you are seeking.
For foundational support, Thorne’s Amino Complex features all the essential amino acids, including the branched-chain amino acids, as well as the conditionally essential aminos L-cystine and L-tyrosine, which serve as important precursors to other amino acids.
Amino Complex is available in a sugar-free powder, in two delicious flavors – lemon or berry – to integrate effortlessly into your daily routine. Both flavors of Thorne’s Amino Complex are NSF Certified for Sport®.
For the individual who is looking for an additional amino acid formulation to further support athletic performance, gut health, or the nervous system, Thorne offers a variety of options for individual amino acid supplements
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