Essential Amino Acids: Role, Sources, and Benefits

What are essential amino acids?

1. Definition and context

Amino acids are the basic units that make up proteins. There are about twenty involved in human biological functions. Among them, nine are considered "essential", because the human body cannot produce them itself: they must therefore be supplied through diet.

The 9 essential amino acids are:

• Leucine,
• Isoleucine,
• Valine,
•  Lysine,
• Methionine,
• Phenylalanine,
• Threonine,
• Tryptophan,
• Histidine.

These amino acids are present throughout the body. They are found in particular in:

• Muscles,
• Enzymes and hormones,
• The immune system,
• The brain. 

2. The link between proteins and amino acids

Dietary proteins (present in foods such as meat, eggs, fish, dairy products, but also legumes and some cereals) are actually chains of amino acids. When you consume a protein, the digestive system breaks it down to extract the amino acids.

It is the quality of a protein (its richness in essential amino acids) that determines its biological value. A protein containing all the essential amino acids in good proportion is said to be complete. Animal proteins are generally complete, while some plant proteins require food combinations to become so.

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The 9 essential amino acids: what are the benefits for the body?

Proteins play a fundamental role in the body. They are essential for building and maintaining muscle mass.

Concretely, when you consume protein-rich foods, the body breaks them down into amino acids to reuse them according to its needs.

Among these amino acids, the 9 essential ones are a priority because the body cannot produce them itself: without them, protein synthesis is incomplete, which can hinder muscle gain. 

Where to find essential amino acids?

Since the body does not produce essential amino acids, it is crucial to supply them through diet. They are mainly found in foods rich in complete proteins, whether of animal or plant origin.

1. Sources of animal protein

Products of animal origin are considered complete proteins: they contain all nine essential amino acids, in ideal proportions for the needs of the human body. They also have high bioavailability, meaning they are easily digested and assimilated by the body.

Among the best sources:

• Lean meat (beef, chicken, turkey)
• Fish (salmon, tuna, mackerel)
• Whole eggs, considered the benchmark for protein quality
• Dairy products (cottage cheese, Greek yogurt, milk)

Good to know: Animal proteins are often richer in leucine, an essential amino acid that stands out for its benefits, especially for athletes. This partly explains why they are very popular in sports diets. 

2. Sources of plant protein

Contrary to popular belief, it is entirely possible to meet your needs for essential amino acids with a plant-based diet, provided you adopt a strategic and varied approach.

Plant proteins are considered incomplete when they lack one or more essential amino acids (often lysine or methionine). However, by judiciously combining several plant foods in the same day, a complete profile can be obtained.

• Examples of good plant sources:
  - Legumes: lentils, chickpeas, kidney beans, broad beans. Rich in lysine, but often poor in methionine.
  - Whole grains: brown rice, oats, barley. Rich in methionine, but lower in lysine.
  - Seeds and nuts: sunflower seeds, hemp seeds, chia seeds, almonds, walnuts. Peanuts provide good amounts of methionine and lysine.
  
  
• Useful food combinations:
  - Legumes and cereals: rice/lentils, chickpeas/couscous, beans/corn.
  - Whole-wheat bread and peanut butter: a plant-based snack rich in complete proteins.

Good to know: Contrary to old beliefs, it is not necessary to combine these foods in the same meal, as long as there is a balanced intake of essential amino acids during the day. 

3. What about food supplements?

Powdered amino acids (BCAA or EAA) can be useful for increasing the intake of these essential nutrients, in a diet or to meet specific sports goals.

However, they do not replace a complete and balanced diet. It is always preferable to prioritize whole foods, which also provide other essential nutrients such as fiber, vitamins, and minerals.

Amino acid supplements: benefits and caution

Amino acid supplements, whether BCAAs (branched-chain amino acids: leucine, isoleucine, valine) or EAAs (complete essential amino acids), are very popular, especially among athletes seeking to increase their intake of these amino acids.

Tips for choosing an amino acid supplement

• Check the composition: Choose products that clearly state the dosages of amino acids, with a good balance between leucine, isoleucine, and valine for BCAAs, or the complete presence of all nine amino acids for EAAs.
• Origin and quality: Opt for supplements from recognized manufacturers, ideally certified without unnecessary additives.
• Adapt to your needs: Taking supplements does not replace a varied and balanced diet. They should be used as a support, especially during intensive training or specific diets.
• BCAA and EAA: what's the difference and how to choose?
  - BCAAs: These are three specific amino acids (leucine, isoleucine, valine) found in large quantities in muscles. However, they do not cover all essential amino acids. Supplementation can be beneficial during intense efforts or periods of dietary restriction.
  - EAAs: This supplement contains all nine essential amino acids, thus offering a complete solution. They are often preferred in contexts where protein quality is an issue, or as a supplement to a diet low in animal proteins. 

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Essential amino acids: in summary

Essential amino acids are the components of proteins, an essential macronutrient for developing and maintaining muscle mass. Since the human body cannot synthesize them, it is essential to obtain them through a balanced diet, rich in quality proteins, whether of animal or plant origin.

Understanding the different types of food and their amino acid profiles allows for better adaptation of one's diet, especially for athletes or individuals with specific nutritional needs. Additionally, BCAA or EAA supplements can be useful as a complement to a varied diet, but should be chosen carefully and used judiciously.