Picture your health as a stone castle. Its strength and stability rely on the precise size and shape of each stone, laid meticulously on top of each other. A missing or poorly sized stone risks the whole structure crumbling.
In the human body, those stones are Amino Acids – organic molecules that combine to form the building blocks of life: proteins. Protein plays a diverse and critical role in all cellular functions.
An imbalance of Amino Acids can significantly impact protein synthesis, potentially affecting digestion, energy production, growth, cognitive function, and recovery from illness or injury.
This article reviews the 20 Amino Acids that link together to form proteins, discusses their diverse functions, and provides strategies to fuel your body with these essential building blocks of health.
What Are Amino Acids and How Do They Work?
As noted above, an Amino Acid is an organic molecule. Each Amino Acid molecule consists of a central carbon atom bonded to an amino group, an acidic carboxyl group, a hydrogen atom, and an R group (known as a side chain). This side chain determines the specific properties and role each Amino Acid plays in protein function.
Every cell in your body combines Amino Acids in specific sequences to build the proteins necessary to sustain you. They are linked together with peptide bonds, forming long chains called polypeptide chains. (Proteins are also known as polypeptides.) The resulting polypeptide chain can be very short (around 50 amino acids) or quite long (up to 2,000 amino acids).
Once the polypeptide chain is complete, it folds into a specific three-dimensional shape. This unique structure is determined by the Amino Acid sequence and is crucial for a protein's function, as it determines its binding sites, active sites, and overall biological activity.
Without proteins, cells would lose their structure, functionality, and ability to communicate and react to their environment. Proteins fulfill countless functions, from building muscle and repairing tissues to producing enzymes and hormones for digestion and energy production. While our bodies can make some Amino Acids, we rely on food for the essential ones.
Essential Vs. Non-Essential Amino Acids
There are 20 different Amino Acids used to build proteins. Amino Acids can be categorized into two groups:
9 Essential Amino Acids:
- Those our body cannot synthesize: Our bodies lack the necessary enzymes to create nine essential Amino Acids, so we must rely on obtaining them from our diet. These are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
- Critical functions: They have irreplaceable roles in building proteins for muscle, enzymes, hormones, neurotransmitters, and other structures and functions vital for survival.
- Deficiency impacts: Lack of even one essential Amino Acid can disrupt protein synthesis, leading to muscle wasting, weakened immunity, impaired metabolism, and potentially severe health consequences.
11 Non-Essential Amino Acids:
- Those our body can synthesize: Our bodies can produce eleven non-essential Amino Acids from other Amino Acids or metabolic intermediates: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.
- Support functions: They contribute to protein synthesis and various functions, often complementing the roles of essential Amino Acids.
- Deficiency: While deficiencies can occur due to certain medical conditions or restrictive diets, they are generally less severe than those of essential Amino Acids.
Since your body handles essential and non-essential Amino Acids differently, you need them both to maintain good health. The combination offers:
- Synergy and efficiency: Non-essential Amino Acids can free up essential Amino Acids for critical functions by supporting protein synthesis. This improves the overall efficiency of protein production and allows the body to prioritize the use of essential Amino Acids where they are needed most.
- Complementary benefits: Each Amino Acid, essential or non-essential, contributes unique properties and functionalities to proteins. Having a complete set of both ensures the formation of diverse and specialized proteins necessary for all bodily functions.
A balanced diet with diverse protein sources is key to meeting the body's requirements for both types of Amino Acids and fostering their ability to build and maintain proteins for all its vital functions.
How to Include Amino Acids in Your Diet
Amino Acids must be present in specific combinations to create functional proteins. Eating both complete and incomplete proteins can help you reach this goal.
What are Complete Proteins?
Certain foods contain all nine essential amino acids. These are called complete proteins and include animal sources like meat, poultry, eggs, and dairy products.
Some plant-based options like quinoa and amaranth belong to this category as well. Consuming complete proteins ensures your body has all the necessary building blocks readily available for protein synthesis.
What are Incomplete Proteins?
Most plant-based protein sources, like beans, lentils, nuts, and seeds, do not hold all nine essential amino acids. While each food is healthy, you need to combine incomplete proteins strategically to be sure you give your body the essential amino acids it needs.
For example, rice and beans, a classic combination, complement each other, providing the missing amino acids in each other's profiles. Another good combination is nuts or seeds with whole grains.
Protein-Rich Foods
It’s not too hard to select foods that provide protein. What’s important is to eat enough of them to meet the minimum Recommended Dietary Allowance (RDA) of 43+ grams for a 150-pound adult. Select from any of the following:
Animal Protein Sources:
- Meat: Beef, pork
- Poultry: Chicken, turkey
- Eggs: Whole eggs
- Dairy Products: Milk, yogurt, cheese
Plant Protein Sources:
- Legumes: Beans, lentils, chickpeas, tofu
- Nuts and Seeds: Almonds, walnuts, chia seeds, hemp seeds
- Whole Grains: Quinoa, amaranth
- Vegetables: Leafy greens like spinach, kale, and chard
Diversity is key! Regularly incorporate various complete and incomplete protein sources in every meal throughout the day to give your body a constant supply of all the essential Amino Acids it needs to make the robust proteins that keep you strong and healthy.
3 Potential Health Benefits of Amino Acid Supplementation
Protein deficiency is not an isolated condition and not a huge issue for most Americans. It is generally the result of malnutrition, especially in children living in poverty. However, eating disorders can create a deficiency, and certain medical conditions can exacerbate deficiencies in certain Amino Acids due to altered absorption, metabolism, or increased needs.
You should not self-diagnose Amino Acid deficiencies. Overlapping symptoms like fatigue, thinning hair or hair loss, edema, muscle mass loss, and skin lesions may indicate an issue.REF#3603 However, it’s critical to communicate with your healthcare provider about any concerns you have before trying to treat yourself.
If appropriate, your healthcare provider can authorize tailored diagnostic tests to indicate your Amino Acid levels. Collaboration is critical for ensuring safe and effective management of potential Amino Acid imbalances.
There is growing evidence that Amino Acid supplementation may provide health benefits in certain situations. Ongoing studies are testing the merits of taking specific Amino Acid supplements to support specific functions.
1. Some Amino Acids May Support Brain Health
Protein malnutrition is a potential risk for senile dementia. A double-blind, randomized, placebo-controlled trial was conducted with 105 participants aged 55 years or older that indicated that a combination of seven Amino Acids may support brain health and social interaction.REF#3604 These seven included leucine, phenylalanine, and lysine supplemented with isoleucine, histidine, valine, and tryptophan.
More research is needed to confirm results and determine what areas of cognition are affected.
2. L-Tryptophan May Support Emotional Health
Eleven randomized controlled trials have shown that taking up to three grams per day of an L-Tryptophan supplement, in addition to eating a healthy meal, may support a positive mood.REF#3605
3. Branched-Chain Amino Acids May Support Muscle Function
Branched-chain Amino Acids (BCAAs) have a unique chemical structure like a forked tree and are found in protein-rich foods like meat, dairy, and legumes. These BCAAs are proven to support muscle growth. The three essential Amino Acids that are BCAAs are leucine, isoleucine, and valine.
One study showed that supplementation with these BCAAs is more effective than rest or passive recovery for muscle recovery.REF#3606 An analysis of nine randomized controlled studies also showed that BCAA supplementation had a positive effect on muscle soreness after resistance exercise.REF#3607
Amino Acid Supplementation Precautions
While Amino Acid supplements are generally safe to take, check with your healthcare provider to determine whether you have a deficiency that would make taking them worthwhile. Also, make sure you’re a supplement won’t interact adversely with any medication you’re taking.
Some people report headaches, nausea, and pain after taking Amino Acid supplements. These supplements may also affect blood sugar levels.
The vast majority of Americans should not need to consider Amino Acid supplementation. As long as you are diligent about eating an adequate amount of protein and a well-balanced plant-based diet, your body is getting the fuel it needs.