Amino acids are organic compounds composed mainly of nitrogen, carbon, hydrogen, and oxygen.
Your body needs 20 different amino acids to grow and function properly. While all 20 of these only 9 are classified as essential i.e. histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Although your body can make nonessential amino acids, it cannot make essential amino acids, so you have to get them from your diet.
The best sources of essential amino acids are animal proteins such as meat, eggs, and poultry. However, some plant foods, such as the soy products edamame and tofu, contain all nine essential amino acids. This means they are “complete” sources of protein.
There are nine essential amino acids, each of which performs a number of important function in your body:
- Phenylalanine. Your body turns this amino acid into the neurotransmitters tyrosine, dopamine, epinephrine, and norepinephrine. It plays an integral role in the structure and function of proteins and enzymes and the production of other amino acids.
- Valine. This is one of three branched-chain amino acids (BCAAs) on this list. That means it has a chain branching off from one side of its molecular structure. Valine helps stimulate muscle growth and regeneration and is involved in energy production.
- Threonine. This is a principal part of structural proteins, such as collagen and elastin, which are important components of your skin and connective tissue. It also plays a role in fat metabolism and immune function.
- Tryptophan. Often associated with drowsiness, tryptophan is a precursor to serotonin, a neurotransmitter that regulates your appetite, sleep, and mood.
- Methionine. This amino acid plays an important role in metabolism and detoxification. It’s also necessary for tissue growth and the absorption of zinc and selenium, minerals that are vital to your health.
- Leucine. Like valine, leucine is a BCAA that is critical for protein synthesis and muscle repair. It also helps regulate blood sugar levels, stimulates wound healing, and produces growth hormones.
- Isoleucine. The last of the three BCAAs, isoleucine is involved in muscle metabolism and is heavily concentrated in muscle tissue. It’s also important for immune function, hemoglobin production, and energy regulation.
- Lysine. Lysine plays major roles in protein synthesis, calcium absorption, and the production of hormones and enzymes. It’s also important for energy production, immune function, and the production of collagen and elastin.
- Histidine. Your body uses this amino acid to produce histamine, a neurotransmitter that is vital to immune response, digestion, sexual function, and sleep-wake cycles. It’s critical for maintaining the myelin sheath, a protective barrier that surrounds your nerve cells.
- May help with mood
- May improve exercise performance and recovery
- May be helpful for wound healing and surgery
Foods that contain all nine essential amino acids are referred to as complete proteins. The following foods are complete protein sources:
- dairy products
Soy and pea protein are plant-based complete protein sources. Other plant-based sources of protein, such as beans, nuts, and certain grains, are considered incomplete proteins because they lack one or more of the essential amino acids.
However, if you’re following a plant based diet, you can still ensure proper intake of all nine essential amino acids by eating a variety of plant proteins each day.
For example, choosing a variety of plant-based proteins, such as beans, nuts, seeds, whole grains, and vegetables, can ensure that you meet your essential amino acid needs, even if you choose to exclude animal products from your diet.
Most people get enough essential amino acids through their diet. However, there are some benefits to taking essential amino acid supplements. For example, athletes often take them to enhance exercise performance and recovery.
Additionally, people may choose to take individual amino acids, rather than blends, to support certain aspects of health, such as mood.