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Protein quality and why it matters

The egg is widely known to be a nutritional powerhouse when it comes to protein and many other important nutrients! In fact, just one large egg contains 6g of protein, as well as 13 essential vitamins and minerals. What fewer people know is that eggs are one of the main sources of the highest quality protein available1. But what do we mean when we say ‘high-quality protein’ and why does it matter?

What it protein and why is it essential?

Proteins are the main building blocks of the body, repairing tissue and allowing our cells to function properly. They are essential to muscle growth, they support our immune systems, and aid child growth.


Professor, MD, DMSc Arne Astrup, member of the International Egg Nutrition Centre’s (IENC) Global Egg Nutrition Expert Group and Director of the Healthy Weight Center, Novo Nordisk Foundation in Copenhagen, explains how protein can benefit different age groups: “It is particularly essential for growing children, to support their development, and the elderly and those suffering from illness, as it helps maintain vital organs and tissues.”

Protein consists of amino acids – but not always the same combinations and ratios. The body uses around 21 amino acids to build different proteins. Nine of these cannot be produced by the body alone, so must be obtained through food – these are known as essential amino acids.

Protein can be found in a range of foods – from beans to beef – but the quality of the protein can vary greatly from source to source.

What do we mean by 'protein quality' and how is it assessed?

Professor Astrup explains: “The quality of protein mainly depends on the composition of different amino acids in the food, and their bioavailability to be digested and absorbed.”

For example, eggs contain all nine essential amino acids, making them a complete protein. Furthermore, the ratio and pattern in which these amino acids are found makes them the perfect match for the body’s needs.

The protein in eggs is also highly digestible - the body can absorb and use 95% of it!


These two factors mean that eggs are one the best sources of high-quality protein available. Scientists have even used eggs as a benchmark for evaluating the protein quality in other foods2.

What are the benefits of consuming high-quality protein?

While the protein in all foods offers health benefits, the higher the quality of the protein, the more easily it can be digested and processed by the body3. This means that your body can reap more benefits from every bite you take.


Professor Astrup explains that a sufficient amount of high-quality protein is essential to good health: “It supports strong bones, muscles, and vital organs, as well as hormone production and disease defence, including immune response to infections.

“Protein also helps to maintain a healthy body weight due to its satiety effect. The combination of protein and dietary fibres make you feel fuller for longer, helping to prevent overweight and obesity.”

We have cracked it

We have always loved eggs for their delicious taste and their versatility… and now we have another incredible reason! Not only are eggs packed with protein, but the protein they contain is high-quality – easily digestible with the right composition of all nine essential amino acids.


"Eggs have a high content of high-quality protein,” Professor Astrup concludes, “which is excellent for human consumption as well as being easy to incorporate into all three daily meals.”

Next time you consider which protein sources to include in your diet, remember that it is not just about quantity, but quality too!



2 Institute of Medicine of the National Academies

3 The Incredible Egg

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