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What is Protein?

 

June 21, 2009 By Tom 36 Comments

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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The Importance of Protein

 

January 28, 2008 By Tom 11 Comments

Lean beef steaks

Proteins are required for the normal functioning of cells in your body. You should be consuming solid protein as part of your daily diet and perhaps protein shakes too. In this article I discuss the importance of protein in greater detail.

Protein is created when amino acids are joined together by peptide bonds. The way the amino acids are sequenced is decided by your genetic code. Proteins are essential for a number of functions in your body such as; metabolism, cell signalling, the immune system, cell adhesion and cell cycle. When proteins enter the body they are broken down into amino acids during the digestion process. These amino acids are then used in areas of the body where they are needed.

Most people associate protein with animal products but a carefully planned vegetarian diet can be rich in proteins too. Below I have outlined some vegetarian and non-vegetarian sources of protein and also discussed the possibility of using protein shakes:

1) VEGETARIAN SOURCES OF PROTEIN:- Protein is lacking in quite a lot of vegetarian foods. However, there are certain vegetarian foods that are rich in protein such as nuts and seeds (including ground nut, cashews and almonds) and soy products (including milk, yoghurt and tofu). It is particularly important for vegetarians to make sure that they find a rich source of protein because this is an area of the diet that they often neglect.

2) NON-VEGETARIAN SOURCES OF PROTEIN:- Protein is a lot easier to find in non-vegetarian foods. Foods which contain protein include; eggs, fish, chicken, meat and milk. Although as a non-vegetarian it is a lot easier to get high protein foods, you should still make sure that you are consuming the recommended levels of protein with your meals.

3) PROTEIN SHAKES:- Athletes and bodybuilders require additional protein to supplement their diets and training efforts. People who are not overly active will use the normal amount of protein supplied in their diets to perform bodily functions. However, people who are highly active (such as athletes and bodybuilders) subject their muscles to an increased level of wear and tear and therefore require additional protein to recover properly. Protein shakes are a quick, convenient way to get this extra protein.

People may also wish to take protein shakes as part of a weight loss diet. Studies have shown that protein can temporarily boost your metabolism and can suppress your appetite. When taking protein shakes it is advisable to limit your intake to a maximum of two servings per day. Increasing your protein intake is OK but excessive consumption of protein can have an adverse effect on your body and your health.

So now you know where to get protein you may be wondering how much is needed? The recommended daily allowances of protein vary based on age and gender, but the following recommended protein intake table gives you a good indication. If you are getting approximately the RDA for protein then you have nothing to worry about. If not this is an issue you need to address. Why? Because apart from the reasons discussed above protein also performs important functions in both children and adults:

1) CHILDREN:- Protein should be a significant component of a child’s diet when they are growing up. As discussed above it is essential for the growth and functioning of cells. This is particularly important for children as they are still growing and developing and so require protein for;
- The building and growth of muscles.
- The support and growth of skin and bones.
- Maintaining healthy eyes and vision.
- Maintaining the immune system (which is extremely important in young children).

Without sufficient protein a child’s growth and development can be hindered. You therefore need to make sure your child is getting the required levels of protein in each meal.

2) ADULTS:- As you age your need for protein does not dwindle. Your body will be subject to constant wear and tear during daily life and protein allows it to be repaired. Proteins are also important for the natural functioning of the body because they transmit nerve impulses. Therefore, you must not neglect proteins just because you are a fully developed adult.

In conclusion, protein is one of the body’s essential building blocks. It is important that you get the RDA of protein throughout your life, from childhood to adulthood. Whether you are vegetarian or not, you should be find adequate sources of protein to meet the recommended levels. With the wide availability of protein shakes available you really have no excuse. However, whilst not consuming enough protein is an issue do not fall into the trap of absorbing too much protein. This can ultimately be just as damaging. As with most areas of your diet – balance is the key.

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