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Quite a few of my previous articles have covered protein. However, after looking back at these articles I have decided that I have not given this topic a good enough write up. That is why today I am going to be writing about protein in greater detail.
WHAT IS PROTEIN?
Protein is one of the three macronutrients that your body depends upon for survival (carbohydrates and fats are the other two). It is constructed from carbon, hydrogen, nitrogen and oxygen which are arranged as long chains of amino acids. There are 22 amino acids in total and your body requires each one for different things.
WHAT ARE AMINO ACIDS?
Amino acids are chemical compounds that contain carbon, hydrogen, nitrogen and oxygen. The 22 amino acids can be grouped under two main headings; essential amino acids and non-essential amino acids.
1) ESSENTIAL AMINO ACIDS:- There are eight essential amino acids. They are labelled ‘essential’ because your body cannot produce them and therefore must source them from food. Even though they have this label they are no more important for the proper functioning of your body than non-essential amino acids. The only difference is that since your body cannot manufacture them it is essential that they are part of your diet. The eight essential amino acids are listed below:
- Isoleucine.
- Leucine.
- Lysine.
- Methionine.
- Phenylalanine.
- Threonine.
- Tryptophan.
- Valine.
2) NON-ESSENTIAL AMINO ACIDS:- There are 14 none essential amino acids. They are labelled ‘non-essential’ because your body can produce them and therefore does not have to rely on food as a source. However, they are still required by the body so that it can function properly and are just as important as the essential amino acids. The 14 non-essential amino acids are listed below:
- Alanine.
- Apartic Acid.
- Asparagine.
- Cysteine.
- Cystine.
- Glutamine.
- Glutathione.
- Glycine.
- Histidine.
- L-Arginine.
- Proline.
- Serine.
- Taurine.
- Threonine.
HOW MANY PROTEINS ARE THERE?
Although proteins are constructed from a limited set of 22 amino acids the number of different protein types is potentially endless. The reason for this is that any number and combination of amino acids can be used to form a protein with the longest known protein – titin being constructed from 26,962 amino acids.
WHAT IS THE DIFFERENCE BETWEEN COMPLETE PROTEINS AND INCOMPLETE PROTEINS?
1) COMPLETE PROTEINS:- Complete proteins are proteins that contain all of the eight essential amino acids. Animal products (meat, fish, dairy) are the richest source of complete proteins with all animal proteins except gelatin considered complete. However, many vegetable products are also complete proteins with bananas, almonds, Brazil nuts, carrots and broccoli being just a few of the complete vegetable proteins available.
2) INCOMPLETE PROTEINS:- Incomplete proteins are proteins that do not contain all of the eight essential amino acids. Many vegetable products are considered incomplete proteins. However, two or more incomplete proteins can be combined to make a complete protein. For example, grains can be combined with nuts or seeds to create a complete protein. This article from BodyforLife2.com contains some more detailed examples of this.
Despite many claims to the contrary you do not need to eat complete proteins (or combine incomplete proteins so that they are complete) as part of every meal. As long as your diet is not consistently lacking one or more of the essential amino acids then it is perfectly fine to eat just incomplete proteins.
HOW DOES YOUR BODY USE PROTEINS?
When you consume protein it is broken down into single amino acids in the stomach and the small intestine. These amino acids are then released into the bloodstream and transported to where they are needed. The cells in your body constantly use these amino acids to create new proteins. If you do not consume sufficient levels of one or more of the eight essential amino acids your body cannot create new proteins effectively. Your body also constantly breaks down old proteins and releases the amino acids back into the bloodstream where they can be recycled or used for energy.
Protein’s main function is to produce, maintain and repair your body’s cells hence the reason it is often referred to as your body’s building blocks. The bulk of your muscles, tissues and organs are made from protein. As discussed above your body’s cells are constantly utilising the amino acids in your bloodstream and creating new proteins which can then be used to build, maintain or repair.
The other functions of protein include:
- Helping your body perform various functions including muscle contraction and nutrient transport.
- Helping your body produce important chemicals such as antibodies, enzymes and hormones.
- Helping keep your hair, nails and skin healthy.
PROTEIN SUMMARY
As you can see protein plays a vital role in the maintenance of your body’s cells. Without protein your cells would break down and your body would be unable to produce new cells or repair your existing ones. Therefore, it is vital that you consume adequate levels of protein and more importantly make sure that the protein you consume is not consistently lacking one or more of the eight essential amino acids.
In my next few articles I plan to discuss the functions of protein in greater detail, outline the disadvantages of consuming too much and highlight some of the best protein food choices around. Before that I want to hear from you guys. Have I missed out any key protein facts? Do you consume sufficient levels of all eight essential amino acids? Leave a comment and let me know.
Sources:
Protein Information (Athens)
Complete Proteins (Raw Food Explained)
How Many Proteins Exist (Wise Geek)
Incomplete vs Complete Proteins (BodyforLife2.com)
What is Protein? (Help with Cooking)
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