Amino acids and proteins: a basic guide to their definitions and differences
Proteins and amino acids are closely related, though differ in their functions and applications. We will explain both, so you can quickly understand the roles of these nutrients in your day to day.
What is an amino acid?
Amino acids are the smallest molecular components that make up proteins. They're made up of carbon, nitrogen, hydrogen and oxygen atoms. Some amino acids, such as methionine and cysteine, also contain sulfur.
There are 20 amino acids found in proteins. Nine are essential, meaning the body cannot produce them on its own. The essential amino acids must be obtained through the diet.
The benefits of amino acids for the body include:
- Development and repair muscles and bones
- Body cell repair
- Energy
- Regulation of metabolic processes
What are essential amino acids?
When the diet lacks amino acids, a healthy human body can synthesize its own amino acids from the supply of other nutrients.
Nine of the 20 amino acids found in proteins cannot be synthesized by the human body and must be consumed in order to avoid malnutrition. That's why these amino acids are called essential.
Essential amino acids include: valine, leucine, isoleucine, threonine, methionine, phenylalanine, histidine, tryptophan and lysine. Histidine, another amino acid, is considered essential for babies.
What is protein?
All proteins are made up of the 20 primary amino acids in various combinations. In this case, the amino acids are linked together like beads in a chain through amide bonds -- also called peptide bonds -- to form proteins. Thus, a protein molecule can have thousands of amino acids in different combinations, providing each protein with unique properties.
Are there better proteins than others?
Yes, the quality of the proteins varies. High-quality or complete protein sources include protein of animal origin. These proteins contain the nine essential amino acids that the body needs to build and maintain muscle and to function well.
Proteins found in most plant foods are considered incomplete, because they lack some of the essential amino acids. Soybeans are the exception and are considered complete based on their amino acid profile.
In this table we can see the quality of proteins provided by different foods:
Source: Whey Protein Institute
As you can see, amino acids form proteins, but humans need to consume those considered essential for optimum functioning. It's important to consider a suitable supplement to obtain them.
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References:
http://www.wheyproteininstitute.org/lifestyle/protein101