A guide to proteins
What is protein?
There are three nutrients that we need in large amounts – proteins, carbohydrates and fats. Proteins in the body are made up of long chains of chemicals called amino acids.
Amino acids can be divided into two groups: non-essential amino acids, which can be made by your body and essential amino acids, which can’t be made by your body and must come from your diet.
Why do we need it?
Proteins are used to develop, grow and maintain just about every part of your body, and they’re hard at work all the time:
- Making up the structure of collagen and elastin, found in skin, nails and hair
- Maintaining, repairing and growing tissue, collagen and bone
- Producing hormones, such as insulin, and enzymes that carry out the chemical reactions in the body’s cells
- Making antibodies to protect against viruses
- Transporting oxygen around your body in the form of haemoglobin in your blood.
These long chains are constantly being broken down, so your body has to replace them every day.
How much protein should we eat?
The recommendation for adults is to eat at 0.75g of protein per kilogram of bodyweight per day. For a person weighing around 12 stone, that’s about 57g/day.
Infants and children, pregnant and breast-feeding women, and people recovering from surgery or injury will need a little more per kilo of bodyweight. This is because their bodies are growing, healing or manufacturing more cells, and protein is vital in these processes.
You’ll also need additional protein in your diet if you want to increase muscle size or you take part in sports such as weightlifting. You can add protein to your diet with a shake as many body-builders do, but most of us get all the protein we need from our food. If you have specific sports-related goals, like building muscle, a professional nutritionist can support you in fuelling your training the best way.
Where can we find protein in foods?
Fish, meat and dairy contain all nine of the essential amino acids. These animal-derived products are known as ‘complete proteins’.
Some proteins, like red meat, are very high in saturated fat, so it’s advisable not to eat beef, lamb or pork foods more than twice per week. Try to choose lean meats such as chicken, fish and low-fat dairy products as your primary source of animal-derived protein.
Animal products are protein dense. The list below shows example food types and the grams of protein they contain per 100g.
- Chicken breast (grilled without skin): 32g
- Beef steak (lean, grilled): 31g
- Salmon (grilled): 24.2g
- Eggs: 12.5g
- Cottage cheese: 12.5g
A few plant protein sources contain all nine essential amino acids, and are known as complete proteins: soya beans, quinoa, millet, avocado, spirulina and chlorella. However, most plant proteins contain only some essential amino acids, so they are known as ‘incomplete proteins’.
Plant-based products tend to contain fewer grams of protein per 100g than animal products.
- Almonds: 21.1g
- Chickpeas: 8.4g
- Red lentils: 7.6g
- Quinoa: 4.4g
- Brown rice: 2.6g
If you eat animal products, your diet will likely contain plenty of protein, but if you are vegetarian or vegan, eating proteins in combinations will ensure you're getting all of the essential amino acids:
- Whole grains (brown rice, quinoa, whole wheat bread) with pulses – whole wheat tortilla with beans, chickpea curry and brown rice, or quinoa salad with puy lentils
- Pulses (beans, peas, lentils) and dairy products (milk, cheese, yoghurt) – baked beans with grated cheese or lentil dhal with natural yoghurt
- Pulses with seeds and nuts – hummus (chickpeas and pine nuts) or mixed bean salad with flax seed oil dressing
- Dairy with whole grains – cheese sandwich with wholemeal bread or porridge with milk
Since your body can’t store protein, it’s best to eat small amounts with every meal or to have a protein-rich snack, to ensure a good supply throughout the day.
Thursday 2 March 2017