16 April 2009

Protein is very essential for the growth of cells and tissue repair and it also works as building block of all life. All proteins are made up of different combinations of 20 compounds called amino acids. Depending on which amino acids link together, protein molecules form enzymes, hormones, muscles, organs and many other tissues in the body.

There are two types of amino acids :
  • non-essential amino acids. Your body can produce it.
  • essential amino acids. You have to take it from your food because your body can’t produce it and there are nine essential amino acids.
Types of protein
Animal protein
Animal proteins contain all the essential amino acids. You can find this protein in meat, poultry, fish, eggs, and dairy products. Oily fish (salmon, sardines, trout, tuna) is a good source of protein. It has the added advantage of being high in types of fatty acid that provide protection against heart attack and to some extent stroke. Oily fish contain up to eight times as much omega-3 and omega-6 fatty acids as lean fish (cod, haddock, skate).
Plant protein

Plant protein contains many amino acids, but no single source contains all of the essential amino acids. Legumes (peas, green beans), cereals, beans, pulses, grains, nuts, seeds, soya products, vegetable protein foods such as Quorn or veggie mince are some of the plants which contain those amino acid.

You need to combine different plant proteins to make up the complete range of amino acids needed by your body.

Plant VS Animal Proteins

In terms of healthy eating, you should aim to eat a diet with a higher proportion of plant proteins than animal ones.

Many animal proteins are high in saturated fat or cooked with a lot of fat.
Studies have linked eating a lot of red and processed meat to an increased risk of bowel and stomach cancer.

Cooking meat, poultry and fish at high temperatures creates chemicals called heterocyclic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs). It's thought HAs and PAHs may increase our risk of cancer, but more research is needed. PAHs are also found in the exhaust fumes and tobacco smoke.

Plant-based proteins are low in fat and high in fibre, vitamins and minerals.
Plant proteins contain phytochemicals that contribute towards health and disease prevention. For example, isoflavones found in soya beans have antioxidant properties.

How much do I need?
Current advice says protein only has to make up 10 to 15% of your daily diet to meet your body's needs. That's around 55g for men and 45g for women.

About two thirds of the protein we eat is from animal sources and get a quarter of our protein from cereal products (wheat, bread, oats).

How much protein do foods contain?
You can check nutrition labels to find out how much protein something contains.
  • One skinless chicken breast (130g): 41g protein.
  • One small fillet steak (200g): 52g protein.
  • One beef burger or pork sausage: 8g protein.
  • One portion of poached skinless cod fillet (150g): 32g protein.
  • Half a can of tuna: 19g protein.
  • One portion of cheese (50g): 12g protein.
  • One medium egg: 6g protein.
  • 150ml glass of milk: 5g protein.
  • One tablespoon of boiled red lentils (40g): 3g protein.
  • One portion of tofu (125g): 15g protein.
  • One slice medium wholemeal bread: 4g protein.
  • One slice medium white bread: 3g protein.

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