Amino acids are the building blocks of proteins, and 20 different types occur naturally in cells. The human body cannot produce the nine essential amino acids. Essential means you must ingest them to survive.
Since your body cannot make these, you must get them from your diet. Since protein is integral to human health, repair, recovery, and general well-being, understanding which amino acids are essential is paramount to a well-balanced diet and lifestyle plan.
Amino acids are essential for many functions in the body, including muscle growth and repair, metabolism, and immune function. They can also be used as a source of energy.
The different types of amino acids can be classified based on their structure. There are two main types: alpha-amino acids and beta-amino acids.
Alpha-amino acids have a central carbon atom bonded to an amino group, a carboxyl group, and a hydrogen atom. Beta-amino acids have a central carbon atom bonded to an amino group, a carboxyl group, and a side chain.
There are also four groups of amino acids: acidic, basic, neutral, and polar. Acidic amino acids have a carboxyl group that is more acidic than the amino group. Essential amino acids have a more basic amino group than the car.
The alkyl side chains are similar to saturated hydrocarbon chains and include glycine, alanine, valine, leucine, isoleucine, methionine, and proline. The final groups are acids--aspartate and glutamate--and bases--arginine, lysine, and occasionally histidine--that form salt bridges.
The 9 Essential Amino Acids
Phenylalanine (or phenylalanine salt) is an amino acid in foods such as meat, fish, and eggs. The body uses phenylalanine to make proteins and neurotransmitters such as dopamine and norepinephrine. Phenylalanine is also needed to produce lipids (fats) and the formation of tyrosine, an essential building block of neurotransmitters.
Foods high in phenylalanine include poultry, seafood, cheese, milk, nuts, and bananas. When a person takes supplements to get extra phenylalanine, it can cause side effects such as nausea or diarrhea.
Excess phenylalanine can also lead to hyperphenylalanism, which occurs when phenylalanine builds up in the body too much due to a lack of the enzyme phenylalanine hydroxylase. Hyperphenylalanism can cause fatigue and dizziness.
Leucine is part of the essential amino acid group called branched-chain amino acids. These can help provide energy to your body, especially after a workout.
Leucine is vital for muscle growth, cell regeneration, and protein synthesis. The best sources of leucine are dairy products, fish, eggs, and meat.
Methionine is an essential amino acid in foods such as meat, fish, and dairy. The body also produces it from other amino acids like cysteine and taurine. Methionine is crucial in making specific proteins and helps maintain a healthy blood sugar level.
Excess methionine can lead to high levels of homocysteine in the blood, which can cause problems with blood vessel walls, nerve cells, and DNA integrity. Elevated homocysteine levels are also linked to increased heart disease and stroke risk.
Proline is an essential amino acid that is found in many foods. It is a type of amino acid that can be synthesized by the body and can also be obtained from the diet.
The human body needs proline for various functions, including maintaining connective tissues and cell growth. Proline is also involved in forming collagen, one of the main components of skin, hair, and nails.
Proline can be found in many foods, including beef, fish, chicken, eggs, and dairy products.
Glycine is a non-essential amino acid that plays an important role in human health. It is found in high amounts of protein-rich foods such as meat and dairy products.
In addition to its role in protein synthesis, glycine is involved in the synchronization of cell signaling. It also has anti-inflammatory properties and may help prevent disease by reducing oxidative stress and inflammation. Glycine also might have anticancer properties.
Glycine can also be synthesized endogenously from glucose by the enzyme glycine dehydrogenase (GDH). This reaction depends not on dietary intake but on metabolic demand.
The body can store up to 3 grams of glycine in muscle tissue anytime. When the need for glycine is high (such as after exercise), the body breaks down stored muscle glycogen to produce more glycine. It has been shown to improve cognitive function and reduce symptoms of depression and anxiety.
Histidine has antioxidant properties and can prevent the build-up of nitric oxide, which can increase blood pressure. The best sources of histidine are chicken, fish, dairy products, beans, and nuts. These foods also contain tryptophan, which is another essential amino acid.
Tryptophan is a precursor to serotonin, one of the human body's most important neurotransmitters. This amino acid can help with mood disorders like anxiety and sleep disorders like insomnia. The best sources of tryptophan are eggs, cheese, and certain nuts.
Threonine helps your body synthesize collagen and protein. Collagen is what keeps skin smooth and youthful, while proteins are what build your muscles.
Threonine can also help lower blood cholesterol. Food sources rich in threonine include poultry, fish, dairy, and beans.
Valine is also one of the branched-chain amino acids and works with leucine to provide energy and synthesize proteins. Valine is important for muscle strength and growth. Food sources rich in valine include dairy products, fish, eggs, and meat.
Isoleucine stimulates the production of hemoglobin in your blood cells. Hemoglobin is what carries oxygen throughout your body.
Isoleucine is also vital for muscle growth and repair. Food sources rich in isoleucine include poultry, fish, eggs, beans, and nuts.
The Benefits of Amino Acids
Amino acids are the building blocks of protein and play a vital role in many bodily functions. Amino acids are involved in a variety of functions, including:
- Building and repairing tissues
- Regulating metabolism
- Synthesizing hormones and other chemicals
- Boosting immunity
- Providing energy
The Best Foods for Amino Acids
Food should always be your first step in optimizing health. And that is especially true with amino acids since you are looking for the most bioavailable form you can find. This is why animal foods shine... they are highly bioavailable while also including adequate protein, amino acids, vitamins, minerals, and essential fatty acids.
Here are some other quality sources of amino acids:
- Eggs: One large egg contains around 6 grams of protein, making it a great source of amino acids. Eggs are also relatively affordable and easy to find.
- Meat: Chicken, beef, and pork are all excellent sources of amino acids.
- Fish: Fish is another excellent source of protein and amino acids. Salmon, tuna, and halibut are all excellent options.
- Dairy: Milk, cheese, and yogurt are all good sources of amino acids. If you're lactose intolerant, many lactose-free options are available these days.
- Nuts and seeds: Almonds, peanuts, and sunflower seeds are all great sources of amino acids. They're also relatively portable, making them perfect for snacking.
Amino acids are the building blocks of protein, and they play an essential role in many bodily functions.
Whether you're trying to gain weight, lose weight, pack on muscle, recovery faster or just feel good over all, protein and amino acids should be the foundational of your diet!