Amino acids , often called the building blocks of protein , are compounds that play many essential roles in your body.
They are needed for vital processes like building proteins and synthesizing hormones and neurotransmitters.
Some can also be taken in supplement form for a natural way to improve athletic performance or improve mood.
They are classified as essential, conditionally essential or non-essential depending on several factors.
This article tells you everything you need to know about essential amino acids , including how they work, possible food sources, and the benefits of taking a supplement.
Amino acids are organic compounds composed of nitrogen, carbon, hydrogen, and oxygen, along with a variable side chain group.
Your body needs 20 different amino acids to grow and function properly. While these 20 are important for your health, only nine amino acids are classified as essential .
These are histidine, isoleucine, leucine, lysine, methionine , phenylalanine, threonine, tryptophan and valine.
Unlike non-essential amino acids, essential amino acids cannot be made by your body and must be obtained through your diet.
The best sources of essential amino acids are animal proteins such as meat, eggs and poultry.
When you eat protein , it is broken down into amino acids, which are then used to help your body with various processes such as building muscle and regulating immune function .
There are several non-essential amino acids that are classified as conditionally essential.
These are considered essential only in specific circumstances such as illness or stress.
For example, although arginine is considered non-essential, your body cannot meet the demands when fighting certain diseases like cancer .
This is why arginine must be supplemented through the diet to meet your body's needs in certain situations.
The nine essential amino acids perform a number of important and varied jobs in your body:
- Phenylalanine: Phenylalanine is a precursor of neurotransmitters tyrosine , dopamine , epinephrine and norepinephrine. It plays an integral role in the structure and function of proteins and enzymes and in the production of other amino acids .
- Valine: The valine is one of three branched-chain amino acids , meaning it has a chain branching off one side of its molecular structure. Valine helps stimulate muscle growth and regeneration and is involved in energy production .
- Threonine: Threonine is a main part of structural proteins such as collagen and elastin, which are important components of skin and connective tissue. It also plays a role in fat metabolism and immune function .
- Tryptophan: Although it is often associated with drowsiness, tryptophan has many other functions. It is needed to maintain proper nitrogen balance and is a precursor to serotonin, a neurotransmitter that regulates your appetite, sleep, and mood .
- Methionine: Methionine plays an important role in metabolism and detoxification. It is also necessary for tissue growth and the absorption of zinc and selenium, minerals essential to your health .
- Leucine: Like valine, leucine is a branched-chain amino acid that is essential for protein synthesis and muscle repair. It also helps regulate blood sugar, stimulates wound healing, and produces growth hormones .
- Isoleucine: Last of the three branched-chain amino acids , isoleucine is involved in muscle metabolism and is highly concentrated in muscle tissue. It is also important for immune function, hemoglobin production, and energy regulation .
- Lysine: Lysine plays a major role in protein synthesis , hormone and enzyme production, and calcium absorption. It is also important for energy production, immune function, and the production of collagen and elastin .
- Histidine: Histidine is used to produce histamine, a neurotransmitter essential for immune response, digestion, sexual function, and sleep-wake cycles. It is essential for maintaining the myelin sheath, a protective barrier that surrounds your nerve cells .
As you can see, essential amino acids are central to many vital processes.
Although amino acids are most recognized for their role in building and repairing muscle, the body depends on them much more.
That's why essential amino acid deficiencies can negatively impact your entire body, including your nervous, reproductive, immune, and digestive systems.
While essential amino acids can be found in a wide range of foods, taking concentrated doses in supplemental form has been linked to several health benefits .
Can help improve mood and sleep
Tryptophan is necessary for the production of serotonin, a chemical that acts as a neurotransmitter in your body.
Serotonin is an essential regulator of mood, sleep and behavior.
While low levels of serotonin have been linked to mood and sleep disturbances, several studies have shown that tryptophan supplementation can reduce symptoms of depression, boost mood and improve sleep .
A 19-day study in 60 older women found that one gram of tryptophan per day led to increased energy and improved happiness, compared to a placebo .
May increase exercise performance
The three essential branched-chain amino acids are widely used to relieve fatigue, improve athletic performance and stimulate muscle recovery after exercise.
In a study of 16 resistance-trained athletes, branched-chain amino acid supplements improved muscle performance and recovery and decreased muscle soreness, compared to a placebo .
A recent review of eight studies found that branched-chain amino acid supplementation was superior to rest for promoting muscle recovery and reducing soreness after exhaustive exercise .
Additionally, taking 4 grams of leucine daily for 12 weeks increased strength performance in untrained men, showing that essential amino acids can benefit non-athletes as well.
Can prevent muscle loss
Muscle loss is a common side effect of prolonged illness and bed rest, especially in the elderly.
Essential amino acids have been shown to prevent muscle breakdown and preserve lean body mass.
A 10-day study of 22 older adults on bed rest showed that those given 15 grams of mixed essential amino acids maintained muscle protein synthesis, while the process decreased by 30% in the placebo group .
Essential amino acid supplements have also been shown to be effective in preserving lean body mass in the elderly and athletes .
May promote weight loss
Some studies in humans and animals have shown that branched-chain essential amino acids can be effective in stimulating fat loss .
For example, an eight-week study in 36 strength-trained men found that supplementing with 14 grams of branched-chain amino acids per day significantly lowered body fat percentage, compared to whey protein or to a sports drink .
A study in rats showed that a diet with 4% supplemental leucine reduced body weight and fat .
However, other studies examining the potential link between branched-chain amino acids and weight loss are inconsistent. Further studies are needed to determine if these amino acids can promote weight loss .
Since your body cannot produce essential amino acids , they must be provided through your diet .
Fortunately, many foods are high in essential amino acids , making it easy to meet your daily needs.
The recommended daily allowances for 1 kg of body weight for the nine essential amino acids are :
- Histidine: 14mg
- Isoleucine: 19mg
- Leucine: 42mg
- Lysine: 38mg
- Methionine (+ cysteine, a non-essential amino acid): 19mg
- Phenylalanine (+ tyrosine, a non-essential amino acid): 33mg
- Threonine: 20mg
- Tryptophan: 5mg
- Value: 24mg
Foods that contain all nine essential amino acids are called complete proteins.
Complete sources of protein include:
- Dairy products
soybeans, quinoa and buckwheat are plant-based foods that contain all nine essential amino acids , making them also complete sources of protein .
others vegetable sources of protein like beans and nuts are considered incomplete because they lack one or more of the essential amino acids .
However, if you follow a plant-based diet, you can still guarantee an adequate intake of all essential amino acids as long as you eat a variety of plant-based proteins each day.
For example, choosing a variety of incomplete proteins such as beans, nuts, seeds, whole grains and vegetables can ensure that your essential amino acid needs are met, even if you choose to exclude products. animals of your nutrition .
There are nine essential amino acids you need to get in your nutrition : histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
They are essential for functions such as protein synthesis , tissue repair, and nutrient uptake.
Some may also prevent muscle loss and improve mood, sleep, athletic performance, and weight loss .
Fortunately, these vital compounds are found in many food original animal and plant , helping you meet your daily needs through a healthy and balanced diet .