Protein

What is protein and why is it so important? Where do we find it and are we getting too much or too little in our diets? Controversy surrounds the issue of protein in the diet, especially with regard to weight loss.   

What is protein?

 
Protein is a source of energy but its main role in the body is in growth and repair. It helps form muscles, hair, nails, skin and organs, such as the heart, kidneys and liver. We all contain a significant amount of protein. For example, a 76kg man is made up of 12kg of protein (16%).
 

Which foods contain protein?

 
Protein is made up of 20 amino acids, some of which our body can make and others we have to obtain from food. It is found in both animal and plant foods, although only animal foods provide all the necessary amino acids. Most plant-based sources of protein, with the exception of soy protein and quinoa, lack one or more of the amino acids we need to obtain from our food. Therefore people who do not eat any animal products (vegans) need a variety of the plant sources of protein every day to ensure they obtain all the necessary amino acids.
 
Animal sources:   meat, fish, chicken, eggs, milk, cheese and yoghurt
Plant sources:      soy protein (such as soy beans, tofu and soy milk), grains (quinoa, oats, barley, etc), nuts and pulses (dried beans, peas and lentils). 
 

How much do we need to eat?

 
The amount of protein  we need depends on our age. 
 

 
Age (years)
RDI
Protein (g/day)
Infants/toddlers
1-3
14
Children
4-8
20
Boys
9-13
40
 
14-18
65
Girls
9-13
35
 
14-18
45
Men
19-70
64
 
>70
81
Women
19-70
46
 
>70
57
Pregnancy
14-18
58
 
19-50
60
Breastfeeding
14-18
63
 
19-50
67

 *RDI = Recommended Daily Intake
 
Few people in New Zealand go short of protein. Here are some examples of how daily protein requirements can be met:
 
A teenage girl can meet her required 45g by eating: 2 lamb leg steaks, 2 slices of wholemeal bread and a pottle of yoghurt.
A 50 year old man can meet his required 64g by eating: a bowl of cereal and milk, 3 slices of white bread and a steak.
 
For your own menu plan which meets all your protein requirements, visit the eMark website.

Who needs more protein 

 

Protein content of foods 
 

 

Protein (g)

1 grilled lean beef fillet steak (135g)

38.2

1 grilled chicken breast (160g)

39.6

1 grilled fillet Hoki (120g)

26.8

1 can tuna in spring water (90g)

25.3

1 grilled pork leg steak (80g)

19.3

1 cup reduced fat milk (260ml)

16.9

1 grilled lean lamb leg steak (60g)

15.1

¼ can boiled red kidney beans (100g)

8.4

Tofu (100g)

8.1

1 pottle plain, low fat yoghurt (150g)

7.2

1 boiled egg (50g)

6.4

3 scoops vanilla ice cream (140g)

4.7

¼ can baked beans in tomato sauce (100g)

4.2

1 slice multigrain bread (45g)

3.6

1 slice white bread (40g)

3.1

10 almonds (10g)

2.5

2cm cube Edam cheese (10g)

2.1

 

Does protein help with weight loss?

 
Protein helps to make you feel full after eating, so including a protein-rich food at each meal can help those trying to lose or maintain their weight. 
 
However, excessively high protein diets are not recommended, especially those omitting other food groups, such as breads and cereals or dairy products. Weight gain is a result of the energy taken in being more than the energy burnt off through metabolism or activity, irrespective of the source of the energy (kilojoules/calories).
 
 

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Photo: Poultry Industry Association