Food facts: everything you need to know about protein


Protein is an essential macro nutrient that we need to eat every day.  It is present in every cell of the human body, which shows why it’s so important. But how much do you know about protein and what are the best sources?

Clinical Nutritionist Suzie Sawyer gives us the low-down on protein: its main benefits, which are the best foods to eat, plus what are the alternatives if you’re vegetarian or vegan?

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Every cell in the human body contains protein: it is a major part of the skin, muscles, organs and glands.  Protein is also used to make the brain’s neurotransmitters (which communicate with other parts of the body), and it is used for growth and development and for the creation of DNA (the key building blocks of life).



Protein is made up of nitrogen-containing molecules called amino acids. They come together in specific combinations to make different types of proteins that form our cells and organs, in much the same way that letters make words to form sentences and paragraphs.

There are actually eight amino acids that are essential for humans; foods that contain all eight are called complete proteins.  Eggs are one example of a complete protein food.



There are two main types of protein – animal and vegetable protein.  Animal protein obviously comes from animal sources such as meat, poultry, fish, dairy produce and eggs.  Animal protein is much more ‘complete’ than vegetable protein, meaning it contains more of the amino acids that make up protein.


Examples of vegetable protein foods include beans, peas, nuts, seeds, soy, tofu, quinoa and lentils.  In order for a vegetarian or vegan to obtain all these essential amino acids, they need to combine both grains and beans during the day (though these don’t necessarily need to be eaten at the same meal).  So for example a corn and beans dish or rice and beans are great combinations.  Quinoa is one of the best sources of protein for vegetarians and vegans: whilst it is a grain, it is also more ‘complete’ than other grains – a great way of topping up those essential amino acids!


There is one source of vegetable protein that is complete – hemp protein.  It’s been around for many thousands of years and also has the benefit of containing some essential fats.  It has a slightly nutty flavour and is a great addition to juices or smoothies for a protein top-up – you certainly don’t need to be vegetarian or vegan to enjoy its benefits!


You should try and eat protein at every meal.  It’s especially important to eat protein at breakfast-time when blood sugar levels are low: by eating a protein-based meal first thing in the morning, such as scrambled or poached eggs perhaps with some wholemeal toast, you’ll start the day with a good level of protein in your system. This will also ensure your energy levels and mood are balanced throughout the day.


Protein is not stored in the body in the same way as fats and carbohydrates, so it needs to be eaten daily. The recommended amount is around 25-30g of protein at each meal.  This is roughly the equivalent of two eggs, a chicken or salmon fillet or a vegetarian chilli con carne containing beans and served with wholegrain rice.  Protein is particularly important for children, whose bodies are growing and developing constantly.


High protein diets have become very popular over the last few years, and whilst some of them may actually contain too much protein, the basic concept of using protein to help with weight loss has merit.

As we know, protein helps to balance blood sugar levels – a key mechanism in managing weight.  If there is too much sugar or glucose in the blood, the body’s natural insulin response will simply send the excess sugar to be stored in the fat cells.  This where a high sugar diet makes effective weight loss very difficult.


Protein also helps the body to feel satisfied for longer, so hunger pangs are controlled and therefore less food is ultimately eaten.  Protein also stimulates the production of CCK, an intestinal hormone that is released after a meal and signals fullness.  It’s actually not true that a carbohydrate-laden meal such as pasta that will keep you feeling fuller for longer – it’s all about the protein.


Everybody needs protein.  However, children are especially at risk of low protein intake, partly because many exist on higher carbohydrate diets that contain lots of pasta or potatoes.  Pasta does contain a small amount of protein but is not sufficient for their daily needs; children should be eating food from the protein groups mentioned above.


The elderly are also at risk of deficiency.  Maintaining muscle mass is particularly important as we age, particularly keeping the legs strong to help prevent falls and broken bones (and protein is a major constituent of bone).  A study published in the American Journal of Clinical Nutrition, found that older men and women who ate the most protein-rich foods lost approximately 40% less muscle mass over three years compared to those who ate the least amount[1].


Certain sectors of the population eat a lot of protein – athletes and body-builders for example.  However, whilst it was once thought that this put additional strain on the kidneys and also caused calcium to be leached from the bones, this is now not thought to be the case. We know that excess amino acids are simply eliminated in the urine from the body.  Therefore, those eating a very high protein diet don’t appear to be at risk.

So in a nutshell, include a range of proteins throughout the day and eat protein at every meal to provide your body with the best support you can.



[1] Houston DK et al.  Dietary protein intake is associated with lean mass change in older, community-dwelling adults.  Am J Clin. Nutr. 81: 150-155


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