Protein is made up of amino acids, building blocks for our bodily tissues and a structural component of every cell in our body, therefore important for growth and repair. It also primarily makes up muscle, hair, skin, nails, eyes as well as internal organs, and also helps form collagen, essential for bone, joints and cartilage.
Protein is needed to make hormones and neurotransmitters, such as our sex hormones, melatonin to aid our sleep, and thyroid hormones to set our metabolism. There are 20 different types of amino acids, of which 8 are ‘essential’ from our food as the body cannot synthesise them on its own.
Protein is broken down into energy more slowly than carbohydrate and has been
shown to delay stomach emptying, making us feel fuller for longer. Because it is broken down more slowly it can support insulin sensitivity and therefore reduce sugar and carbohydrate cravings. Spreading our protein intake throughout the day, and including it with every meal, gives our bodies a better chance to use these building blocks and maintain muscle mass.
How much?
In the UK, the Reference Nutrient Intake is 0.75g protein, per kg of body weight e.g. for a 75kg male, this would mean a daily intake of 56.25 grams. This is roughly equivalent to about 15% of daily calories. However, children, pregnant and breastfeeding mothers have greater needs, and arguably as we age, to protect against (muscle wasting). Athletes and frequent exercisers will also need more.
The quality of protein is also important, dependent on the variety of amino acids in the food source, which impacts how biologically available they are for us to use. Combining plant sources such as rice and lentils can help ensure the full range of amino acids are being consumed. Protein in excess can cause damage, particularly to those with kidney disease because of the excess nitrogen that the kidneys have to work harder to get rid of.
Best sources
Unsurprisingly, meat, fish, eggs, nuts, seeds, dairy products, pulses, beans and grains provide us with the range of amino acids needed. Whilst vegans can certainly get adequate protein from their diet, most plant sources do not contain the full spectrum of the 20 amino acid therefore, variety and food combining is
required. Vegan protein powders made from pea, hemp, soy, and rice are growing in popularity, also as an alternative to whey based powders for those with dairy
intolerances.