Protein is the building block of life. Here’s what, why and how much you really need.
Reviewed by Jeni Worden
From workout shakes to energy bars, everything is packed with protein these days, but this humble macronutrient is not merely a diet fad. Protein is the building block of all life and is essential for the growth of cells and tissue repair.
Protein is also responsible for making enzymes, hormones, and other body chemicals. It also plays a vital role in building bones, muscles, cartilage, skin, and blood. Here’s everything you need to know about protein, including the best food sources:
What is protein?
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: these can be made by the body.
- Essential amino acids: these cannot be made by the body, so they must be acquired from food. There are eight essential amino acids for adults and a further seven that children need.
The different types of protein
There are two main types of protein, both of which are essential for health and development:
? Animal protein
Animal proteins contain all the essential amino acids. This type of protein is found in:
- 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 attackand 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).
The cons of animal protein
Many animal proteins are high in saturated fat or cooked with a lot of fat (oil, lard, dripping). 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.
✔️Try this: Processed foods should be eaten in moderation. Sausages and burgers may be the obvious culprits. But so are smoked foods, which are also high in salt. Try to keep foods, such as smoked bacon and salmon, to occasional treats.
? Plant protein
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, thought to be important in the prevention of cancer and menopausal symptoms.
Plant protein contains many amino acids, but no single source contains all of the essential amino acids. This type of protein is found in:
- Legumes (peas, green beans)
- Soya products
- Vegetable protein foods, such as Quorn or veggie mince
✔️ Try this: You need to combine different plant proteins to make up the complete range of amino acids needed by your body. In practice, this is achieved without any special effort, for example by eating baked beans with bread (toast) or using milk on cereal.
⚠️ In terms of healthy eating, you should aim to eat a diet with a higher proportion of plant proteins than animal ones.
How much protein do you need?
Current advice says protein only has to make up 10 to 15 per cent of your daily diet to meet your body’s needs. That’s around 55g for men and 45g for women.
Most of us eat more than this, and the British Nutrition Foundation puts the average adult intake at 88g for men and 64g for women.
- Around two thirds of the protein we eat is from animal sources.
- We get a quarter of our protein from cereal products (wheat, bread, oats).
- Nuts and pulses make up most of the final twelfth.
Energy and protein
- 1g carbohydrate: 3.75 calories.
- 1g protein: 4 calories.
- 1g fat: 9 calories.
- 1g alcohol: 7 calories.
How much protein do foods contain?
Below are some examples of foods, so you can compare protein content. It is also worth checking 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.
Tips for healthy living
To get the most from both animal and plant proteins, incorporate the following tips into your lifestyle:
✔️ Include oily fish in your diet at least twice a week.
✔️ Try using soya products, such as veggie mince and tofu. They will take up the flavour of the dish if you add them to stews and sauces.
✔️ Snack on seeds and unsalted nuts. Try sunflower, pumpkin or sesame seeds and brazils, cashews, walnuts, hazelnuts or almonds.
✔️ Look at using pulses as an alternative source of protein. They include chickpeas, a wide range of lentils, split peas and a vast range of beans from the black-eyed to the broad, butter and kidney.
✔️ Eat one vegetarian meal each week.
Is it healthy to eat meat?
You don’t need to banish meat from your diet altogether to maintain a healthy lifestyle. Try the following:
- Use lean cuts of meat and poultry.
- Trim off any fat, eg the skin on chicken breasts and the rind on bacon.
- Choose smaller portions.
- Reduce the frequency of meat-based meals.
- Pay particular attention to how you cook meat.