What is protein?

what is protein

The basic building blocks

Proteins are the basic building blocks of the human body. Next to water, protein is the most plentiful substance in the body, and most of it (around 60% to 70%) is located in the skeletal muscles.

Proteins are highly complex molecules comprised of linked amino acids. Amino acids are simple compounds containing carbon, hydrogen, oxygen, nitrogen and occasionally sulphur.

Protein = Amino acids

Proteins are broken down into their constituent amino acids during digestion; these are then absorbed and used to make new proteins in the body. There are 20 amino acids that are required for growth by the human body and all but eight can be produced in an adult body. These eight amino acids are called essential amino acids and must be supplied to the body by food or supplements. The eight essential amino acids required by humans are: leucine, isoleucine, valine, threonine, methionine, phenylalanine, tryptophan, and lysine. For children, histidine is also considered to be an essential amino acid.  Both essential and non-essential amino acids are necessary for the synthesis of tissue proteins. Amino acids link together to form chains called peptides. Each protein has it's own unique number and sequence of amino acids which determines it's particular structure and function.

Complete protein

A complete protein is a source of protein that will contain all the essential amino acids that the body needs, whereas an incomplete protein source does not. Examples of complete proteins are usually animal products such as meat. Incomplete proteins are usually found in plant sources such as seeds or nuts. Combining some of these incomplete protein sources will give you a meal that contains all the essential amino acids.

Protein is absorbed in to the body and broken down in to amino acids; this is essential for the correct running of your body. Protein is required by the body for the growth, maintenance and repair of all cells. Protein is a major component of all muscles, tissues and organs.

Muscle growth

Proteins are essential for growth and repair. They play a crucial role in virtually all biological processes in the body. All enzymes are proteins and are vital for the body's metabolism. Muscle contraction, immune protection, and the transmission of nerve impulses are all dependent on proteins. Proteins in skin and bone provide structural support. Many hormones are proteins. Protein can also provide a source of energy. Normally the body uses carbohydrate and fat for energy but when there is excess dietary protein or inadequate dietary fat and carbohydrate, protein is used. Excess protein may also be converted to fat and stored.

For muscles to grow and tissue to repair your body needs enough protein; when taking up an activity such as a sport, or joining the gym the amount of protein your body requires will increase. Strength athletes and bodybuilders in particular need to increase their protein intake to get the most out of their training. 

Protein stores

Your body can not store large amounts of amino acids, when too many are present your body will try to expel them. They are broken down by the liver and passed through the kidneys to be expelled in urine. 

Read more from our protein series:

Related Articles

Diet DIY - an end to rigid diets.

Basic Diet Construction - A step by step...

Eat less wheat for a healthier, skinnier you

Like most foods these days, depending on the...

Don't let the gym beat you before you've even started

Joining a gym should be as simple as choosing...

Where does my energy come from?

The energy in our body is generated in the form...