Protein sources and their quality

Many foods contain proteins, and some people tend to believe that a plant-based diet can provide as good a protein intake as a meat-based diet. However, this is not entirely the case. Proteins come in many forms, and just as fat molecules differ between saturated and unsaturated fat there is also a difference in the composition of amino acids in proteins. It is therefore important to distinguish between protein sources, as their content of protein and amino acids differ.

This also means that the quality of the proteins varies. Research shows that protein quality is generally higher in animal than in vegetable food products. In addition, most animal protein sources have higher protein content than the content from vegetables.

Protein quality: What and how?
Plant-based foods are still gaining ground with many people, but this comes at a cost in terms of protein quality. The quality of a food protein can be measured on three different levels - digestibility, utilisation and anti-nutrients.

Digestibility is an important factor in the assessment of protein quality as it refers to the absorption of amino acids in the body. Digestibility varies depending on the source of the protein and is often lower for plant-based proteins than for animal proteins. In general, plant-based proteins have a digestibility of about 50-70%, while animal proteins have a digestibility of about 70-90%.

Utilisation refers to the degree to which an amino acid is absorbed in a form that the body can use, if it is absorbed through the gut at all. Even if an amino acid is digestible, it does not necessarily mean that the body can use it efficiently. Different protein sources may have different levels of utilisation and this can affect protein quality.

Anti-nutrients are a group of substances in food that can inhibit absorption or utilisation of nutrients, including amino acids. These substances are found more extensively in plant-based foods than in animal protein sources. For example, phytic acid can inhibit absorption of protein and minerals. Anti-nutrients thus have a negative impact on protein quality and on the body's ability to utilise amino acids found in food.

A diet with a greater proportion of plant-based protein sources requires more knowledge about protein quality and how to combine different foods to achieve the best possible protein quality. This is because plant-based proteins typically have lower digestibility and utilisation compared to animal proteins and may contain anti-nutrients that can affect the absorption of amino acids. In addition, individual animal protein sources contain all nine essential amino acids. The human body cannot produce the essential amino acids by itself. They must be taken in through what we eat. In most cases, two or more vegetable protein sources are needed to obtain sufficient quantities of all essential amino acids.

Intake of protein across national borders
In general, the Nordic countries do well when it comes to protein intake. This is reflected in the recommendations issued by the respective food authorities. However, the recommended minimum intake of proteins gives a varying picture of how much protein is actually needed in the diet.

The World Health Organization (WHO) recommends a daily intake of proteins based on body weight. The intake is expressed in grams per kg of body weight. This means, for example, that a woman weighing 60 kg with an intake of 2000 calories per day must have a daily intake of 0.83 g of protein per kg of body weight.

The Nordic Nutrition Recommendations (NNR) and the Danish Veterinary and Food Administration (FVST) recommend a daily intake of proteins that differ from WHO’s. NNR and FVST recommend that the intake of proteins should be measured as a percentage of total energy intake (calorie intake) at 10-20%. In their calculations, NNR has taken the Nordic food culture into account. NNR's calculations mean that out of the total amount of energy from the food we eat in a day,10-20% must be energy from protein.

In Germany, the recommended daily intake of protein is estimated at 0.8 g of protein per kg body weight for healthy adults. For a person weighing 70 kg, this corresponds to 56 g protein per day. Studies show that the daily intake of protein in Germany is above the minimum recommendations. For example, the average protein intake is 85 g for men, while the average intake for women is measured at 64 g. Looking at the quality of the protein we consume will become increasingly important in the future. It may appear that we are well covered in terms of quantity, but if the quality is lacking it does not promote or maintain human health.

The Swedish Food Safety Authority recommends a daily protein intake of 15% of the energy intake. This corresponds to approximately 75 g of protein for a person eating 2000 calories a day.

According to the British Nutrition Foundation, the daily reference intake of protein for adults is 0.75 g per kg body weight. This corresponds to approx. 56 g protein per day for men, and 45 g per day for women. This also applies to children, pregnant and lactating women.

UK: https://www.nutrition.org.uk/healthy-sustainable-diets/protein/

Are you interested in knowing more about the amounts of protein in various foods? In this overview, you can take a closer look at the protein content in different foods.