What are Amino Acids?

What are Amino Acids?

Your body is made up of more than 100,000 different proteins that all have essential functions.¹ This encompasses everything from transporting oxygen (hemoglobin) to regulating blood glucose levels (insulin) and providing structure (collagen) to enabling muscle contraction (myosin). Amino acids are an important class of biomolecules that serve as an energy source and the building blocks of these proteins. The first amino acid, asparagine, was isolated from asparagus juice in 1806. Since then, researchers have identified 20 standard amino acids the human body uses to function and thrive.^2,3

Essential Amino Acids

Of these 20 amino acids, nine are termed essential because our bodies cannot synthesize them.⁴ This means that we must be sure to incorporate these amino acids into our diet.

1. Histidine: Histidine is critical in the synthesis of several proteins and peptides. It is also a precursor to histamine, a neurotransmitter essential in digestion, immunity, sleep-wake cycling and sexual function.⁵
2. Isoleucine: A branched-chain amino acid (BCAA), isoleucine helps with energy regulation and immune function. It’s essential during physical activity.
3. Leucine: Another BCAA, leucine stimulates muscle protein synthesis and supports wound healing, blood sugar regulation and energy production.
4. Lysine: Essential for collagen formation, calcium absorption, and hormone and enzyme production. Lysine also supports immune health and plays a role in regulating mood and stress response.
5. Methionine: A sulfur-containing amino acid, methionine is crucial for metabolism and detoxification. It also helps with the absorption of selenium and zinc.
6. Phenylalanine: This amino acid is a precursor to neurotransmitters like dopamine, norepinephrine and epinephrine, making it important for mood, alertness and memory.
7. Threonine: Key for building structural proteins like collagen and elastin, threonine also plays a role in fat metabolism and immune function.
8. Tryptophan: Famous as the precursor to serotonin, tryptophan helps regulate mood, sleep and appetite. It’s also used in the production of niacin (vitamin B3).
9. Valine: The third BCAA, valine, supports muscle growth and tissue repair and helps with energy production during physical activity.

Conditionally essential amino acids are amino acids that are usually non-essential (your body can produce them). Under certain conditions, such as illness, stress, or during infancy, they must be obtained through the diet because the body can’t make enough of them. Common conditionally essential amino acids include:

• Arginine – Increases production of the important vasodilator nitric oxide, which improves blood flow and a key player in healthy cardiovascular function
• Cysteine – Is essential to the structural integrity of cell membranes and forms part of structural proteins such as connective tissue and the myelin sheaths around neurons.
• Glutamine – Is crucial for gut health, immune function and protein synthesis.
• Tyrosine – Is central in the formation of many hormones and neurotransmitters.
• Glycine - Acts as a neurotransmitter and forms part of collagen.
• Proline - Plays a role in gut and skin health and is essential for collagen formation.
• Serine - Is crucial for the synthesis of antibodies, fat metabolism, and the production of proteins and enzymes.
• Ornithine – Aids in nitrogen removal in the urea cycle and may support muscle recovery.

Benefits of Amino Acids

Most people can get all the amino acids they need through a healthy, balanced diet. However, if you have specific wellness goals in mind, you may benefit from taking amino acid supplements.

Support Muscle Growth and Repair

Amino acids, especially the branched-chain amino acids (BCAAs) leucine, isoleucine and valine, play a crucial role in muscle protein synthesis. Supplementing these amino acids or including them in your diet can help repair muscle tissue after exercise and promote the growth of lean muscle mass.⁶

Enhance Exercise Performance

Amino acid supplementation can help reduce fatigue and improve endurance during physical activity. BCAAs serve as an energy source during prolonged exercise and may delay muscle soreness and reduce exercise-induced muscle damage.⁷

Aid in Weight Management

Certain amino acids, like L-carnitine and arginine, can support metabolic functions that contribute to fat loss and lean body composition. Amino acids may also increase satiety, helping to control appetite and reduce overall calorie intake in combination with a balanced diet.

Boost Immune Function

Amino acids such as glutamine are vital for maintaining a strong immune system. They serve as an energy source and support the function of immune cells. During times of stress, illness or intense physical exertion, the body’s demand for these amino acids increases and supplementation can help fill the gap.

Improve Mood and Cognitive Function

Amino acids like tryptophan, tyrosine and phenylalanine are precursors to neurotransmitters such as serotonin, dopamine and norepinephrine. These chemicals influence mood, sleep, concentration and overall mental well-being. Supplementing with these amino acids may help manage day-to-day stressors and symptoms of occasional anxiousness.⁸

Promote Healthy Skin, Hair and Nails

Amino acids are the building blocks of collagen and keratin—proteins essential for strong, vibrant skin, hair and nails. Nutrients like proline, glycine and cysteine support the body’s ability to maintain skin elasticity, promote wound healing and enhance overall appearance.

Support Hormone and Enzyme Production

Many hormones and enzymes in the body are composed of amino acids. Adequate intake ensures optimal metabolic and physiological functioning, influencing everything from digestion to growth and reproductive health.

Aid in Detoxification and Liver Function

Certain amino acids, including methionine and cysteine, play a role in the body’s natural detoxification processes. They support liver function by helping to neutralize and eliminate toxins. This can improve overall health and reduce the burden of environmental stressors on the body.

Help Regulate Blood Sugar Levels

Amino acids like leucine and isoleucine can help regulate blood glucose by enhancing insulin sensitivity and supporting metabolic processes. When included as part of a balanced diet, they may assist in energy management and support individuals with metabolic challenges.

Amino Acid Food Sources

Food sources that contain all nine essential amino acids are called complete proteins. Dairy, eggs, fish, meat and poultry are dietary sources of complete proteins. Plant-based sources of complete proteins include amaranth, buckwheat, hemp seeds, seitan, soy products and quinoa. While other plant foods also contain proteins, they may not contain all nine essential amino acids and are considered incomplete proteins. However, by eating a variety of plant foods, you can still consume all the amino acids your body needs.

When to Take Amino Acids

The best time to take amino acid supplements—whether pre-workout, intra-workout or post-workout—depends on your fitness goals and the type of workout supplements you're using.

• Pre-Workout: Taking amino acids, especially branched-chain amino acids (BCAAs) or essential amino acids (EAAs), before exercise can help reduce muscle breakdown and improve endurance. This is particularly helpful if you're training in a fasted state or doing high-intensity workouts.
• Intra-Workout: Sipping on amino acids during your workout can provide muscle tissue support, hydration and energy, especially during long or intense training sessions. This can help delay fatigue and improve performance.
• Post-Workout: Consuming amino acids after exercise helps kickstart the recovery process by promoting muscle protein synthesis and reducing soreness. This is often the most common time people take EAAs or protein shakes containing amino acids.

Bottom line: If you want to choose just one time to take workout supplements, post-workout is typically the most beneficial for muscle recovery and growth. However, for maximum impact, especially during rigorous training, you might benefit from a combination of pre- and post-workout or even intra-workout amino acid intake.

Who Should Take Amino Acid Supplements?

Supplementing with an amino acid complex can benefit a wide range of people. However, certain groups may see greater advantages based on their activity level, age, health status, and dietary habits.

Athletes and Active Individuals

Those engaged in regular strength training, endurance sports or high-intensity workouts can benefit from amino acids to support muscle recovery, reduce fatigue and enhance performance.

People with Low Protein Intake

Individuals on restrictive diets (like vegans or vegetarians) or those who struggle to meet daily protein needs due to appetite or health issues, may find amino acid supplements help fill nutritional gaps.

Older Adults

With age, the body becomes less efficient at synthesizing protein, leading to muscle loss (sarcopenia). Amino acids—especially leucine-rich EAAs—can help preserve muscle mass and strength in older adults.

Those Recovering from Illness or Surgery

Amino acids can support healing and immune system function by providing the building blocks for immune cells and proteins and regulating immune cell function. This is particularly important during recovery from illness, injury or surgery as the body’s demand for protein is higher.^9,10

Physically Stressed Individuals

People under significant physical stress, such as shift workers, those with certain health challenges, or individuals recovering from intense physical exertion, may benefit from amino acids to help combat muscle breakdown and fatigue.

Amino Acids: Small Molecules, Big Impact

Amino acids are truly the foundation of life—vital molecules that support nearly every function in your body, from building muscles and maintaining skin health to producing hormones and boosting your mood. While a well-rounded diet can typically provide all the amino acids your body needs, supplementation may offer added benefits for athletes, older adults, those recovering from illness or individuals with dietary restrictions. Whether you're looking to enhance your workouts, support recovery or optimize your overall health, understanding the role of amino acids is a powerful step toward achieving your wellness goals.

You be well, now.

Swanson

 

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

 

References:

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4. Lopez MJ, Mohiuddin SS. Biochemistry, Essential Amino Acids. Updated 2024 April. Read more
5. Brosnan M, Brosnan J. The Journal of Nutrition. 2020 Oct;150(1 Suppl):2570S-2575S. Read more
6. Khemtong C, Kuo CH, et al. Nutrients. 2021 May 31;13(6):1880. Read more
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9. Dreyer HC, Owen EC, et al. JB JS Open Access. 2018 Jun 4;3(2):e0006. Read more
10. Cogo E, Elsayed M, et al. Integrated Cancer Therapy. 2021 Jan-Dec;20:1534735421997551. Read more