Proteins have long been considered very important nutrients, in fact the word ‘Protein’ is derived from the Greek and means ‘Holding first place’.
Although proteins are often associated with strength and muscle power, this is only partially true; although an essential component of muscles, proteins play all sorts of roles in maintaining our health and functionality.
Different Proteins
Here are some of the most common proteins, along with their functions in the body:
- a-Keratin and Collagen: maintain healthy skin, hair and connective tissue
- Myosin and Actin: involved in muscle growth and repair
- Haemoglobin: transports oxygen in the blood
- Fibrinogen and thrombin: provides defence against foreign bodies, and causes blood-clotting
- Insulin: regulates metabolism
- Myoglobin: stores oxygen in muscles
- All hormones are proteins
Amino Acids
All proteins are made up of smaller molecules called amino acids. The body is able to synthesise the majority of amino acids on its own; however, some amino acids cannot be built in this way and must be supplied by the diet. Amino acids that must be supplied by the diet are known as Essential Amino Acids.
What is the Best Source of Protein?
People tend to think of meat as being the best source of dietary protein, but in fact proteins from plant and animal origin are equally beneficial.
‘Animal’ protein is found in:
- Red meat
- Chicken
- Fish
- Dairy Products
- Eggs
Animal proteins are high in Essential Amino Acids in the right proportion, and are therefore known as Complete Proteins. However, the Complete Proteins can be high in saturated fat and low in fibre.
‘Plant’ protein is found in:
- Fruit and vegetables
- Nuts
- Seeds
- Beans
Plant proteins tend to be high in fibre and low in fat, but do not always have all the Essential Amino Acids, and so are known as Incomplete Proteins. It is perfectly possible for vegetarians to obtain sufficient Essential Amino Acids, as long as they eat a wide-ranging and varied diet.
How Much Protein Do We Require?
The World Health Organisation recommends that an average person requires about 1 gram of protein per kilogram of bodyweight per day, or approximately 10-15% of total calorie intake. For example, a person weighing 65kg requires 65g protein per day.
Some studies have indicated that an endurance athlete requires approximately 1.2-1.8g protein per kg of bodyweight per day, with a strength/power athlete requiring up to 2kg protein per kg bodyweight per day.
Excessive consumption of protein can cause:
- Osteoporosis
- Arthritis
- Kidney damage
- Excessive calories from protein can be stored as fat, just like calories from fats and carbohydrates
Inadequate consumption of protein can lead to:
- Prolonged recovery from illness
- Low energy levels
- Low stamina levels
- Poor resistance to infection
- Mental depression
- Slow healing of wounds
However we are currently seeing a trend for high-protein diets, and far more people in the Modern Western World consume too much protein, rather than not enough!
For information on carbohydrates visit Do Carbohydrates Make You Fat?
 |
