Protein is a vital part of all body cells. It makes up about half of the human body’s dry weight (Brain cells, muscle, skin, hair and nails are just some of the body parts that are protein-based.).The human body can’t store protein, so it must be supplied on a daily basis from the foods we eat .Many of the foods we eat contain protein, particularly flesh foods (chicken, beef, lamb and fish) and legumes,(kidney beans, lentils, chick peas).
Proteins contain 4 Calories energy per gram
Proteins are digested to release amino acids. In the body the amino acids are used to make new proteins, converted into hormones such as adrenalin or used as an energy source.
How much protein you need?
The amount of protein you need in your diet depends on your weight, age and health. As a rough guide, the recommended dietary intake (RDI) for protein (measured in grams per kilogram of bodyweight) is:
- 0.75g/kg for adult women
- 0.84g/kg for adult men
- Around 1g/kg for pregnant and breastfeeding women, and for men and women over 70 years (to maintain muscle mass and strength)
- Larger amounts are required during times of growth, especially during times of childhood, adolescence and pregnancy.
- Most Australians eat far more protein than they actually need, so deficiencies are rare.
- Strength Training Adults (4 x a week or more)should increase intake to 1.5g/kg.
Sources of protein
Meat, poultry and fish
Seeds and nuts
Beans and lentils
Grains, barley and corn..
Protein Supplements – Whey, Casein, Soy, Rice, Egg
Amino acids explained
Proteins are made up of chains of smaller chemicals called amino acids.
Amino acids are the building blocks of proteins and are used for building new tissue.
There are 20 major different types of amino acids each with different roles in the body.
There are two broad classes of amino acid: those that can be made by the human body (non-essential amino acids) and those that can only be supplied by food (essential amino acids).
There are 9 essential amino acids that must be supplied by our food intake. Some specific proteins require these amino acids to synthesize and failure to provide them results in muscle breakdown
On the other hand, non-essential amino acids can be made by the body from other amino acids.
The human body uses AMINO ACIDS in three main ways:
Protein synthesis – new proteins are created constantly. For example, as old, dead cells are sloughed off the skin surface, new ones are pushed up to replace them.
Precursors of other compounds – a range of substances are created using amino acids: for example, the brain chemical (neurotransmitter) serotonin and the ‘fight or flight’chemical adrenalin.
Energy – although carbohydrates are the body’s preferred fuel source, about 10 % of energy is derived from protein.
Complete Proteins and Incomplete Proteins
A complete protein contains an adequate amount of all of the essential amino acids that should be incorporated into a diet. Some protein contains all the amino acids needed to build new proteins, which generally come from animal and fish products. A complete protein must not lack even one essential amino acid in order to be considered complete.
Sources of Complete Proteins
The following foods are examples of complete proteins, which need not be combined with any other food to provide adequate protein:
Meat , Fish , Poultry , Cheese , Eggs , Yoghurt , Milk
An incomplete protein is any protein that lacks one or more essential amino acids in correct proportions. These can also be referred to as partial proteins. Even if the protein contains all the essential amino acids, they must be in equal proportions in order to be considered complete. If not, the protein is considered incomplete.
Sources of Incomplete Proteins
The following foods are examples of incomplete proteins:
Grains , Nuts , Beans , Seeds , Peas
Combining Incomplete Proteins to Create Complete Proteins
By combining foods from two or more incomplete proteins, a complete protein can be created. The amino acids that may be missing from one type of food can be compensated by adding a protein that contains that missing amino acid. When eaten in combination at the same meal, you are providing your body with all the essential amino acids it requires. These are considered complementary proteins when they are combined to compensate for each other’s lack of amino acids.
Samples of Complementary Proteins
Examples of combined complementary proteins to create a complete protein in one meal include:
- Grains with Legumes – sample meal: lentils and rice with yellow peppers.
- Nuts with Legumes – sample meal: black bean and peanut salad.
- Grains with Dairy – sample meal: white cheddar and whole wheat pasta.
- Dairy with Seeds – sample meal: yogurt mixed with sesame and flax seeds.
- Legumes with Seeds – sample meal: spinach salad with sesame seed and almond salad dressing.
By learning what foods complement each other, it is possible to create a perfectly balanced meal with the proper proportions of proteins. This will ensure that your body is getting all the essential amino acids it requires for optimal bodily functions.
A diet deficient in Protein can cause amongst other things Wasting and shrinkage of muscle tissue and Anaemia (the blood’s inability to deliver sufficient oxygen to the cells, usually caused by dietary deficiencies such as lack of iron) but on the Flip Side to this a diet too high in Protein is not good for us as the body will only use the precise amount of protein it needs. The rest will be excreted in the urine and excess amount may even cause liver and kidney strain as they work hard to get rid of the excess nitrogen. It can also cause an increase in calcium loss in the urine as well as dehydration.