Summary of protein quality
- The quality of the protein is important for optimum intake
- Quality is taken into consideration when determining the WHO recommended protein intake
- Despite high protein intake, many adults are at risk of deficiency due to poor quality proteins.
- Animal proteins are often higher quality, while plant-based proteins can be lower in quality.
- Combinations of animal protein can still provide similar benefits
Protein is a hot topic. The popularity of protein has exploded as consumers seek out the nutrient. Almost every food product now boasts a ‘high-protein’ claim.
The consumer wants more protein. When it comes to proteins, quality is just as important as quantity.
What does protein quality mean?
In many respects, the quality of protein can be just as important to your diet as its quantity.
Proteins are necessary for the body to produce body proteins.
The most essential amino acids are found in different quantities depending on the source of protein.
Protein quality can be defined as the source of protein’s ability to supply essential amino acids.
It is not just about the availability of amino acids but also their digestibility.
How does the quality of protein affect health?
It is important to consider the quality of the protein when determining the daily recommended amount. The World Health Organisation and Food and Agriculture Organisation both recommend a certain quantity.
WHO/FAO recommends consuming 0.83 g protein daily per kilogram of bodyweight, with a score of Digestible Indispensable Acid Score (DIAAS), which is the best quality of proteins.
However, the quality of protein is frequently neglected. This can result in a protein deficiency.
A study on the subject suggests that many people who are concerned about food security may be underestimating the amount of protein required for a sustainable diet by focusing only on gross protein intake.
The study found that the average adult was deficient in proteins when the quality of the protein is considered.
If the quality of the proteins isn’t taken into consideration, even if there is an abundance available one may still have a deficiency.
In the United States where people are able to get enough protein, a study found that low-quality protein consumption can still lead to nutrient deficiencies.
Animal sources are the main source of high quality proteins
Plant-based protein sources are often inferior to animal sources and scored lower in protein quality tests such as DIAAS.
DIAAS
Food and Agriculture Organisation of the UN (FAO) has endorsed the Digestible Indispensable Amino Acid Score as the best rating for protein quality. It replaces the old Protein Digestibility Corrected Amino Acid Score.
It has also been criticized for focusing too much attention on isolated, individual foods and not enough on the matrix of food (the structure and interactions between the molecules in the food).
The amino acid profiles of plant-based foods are lower and the amino acids available and digestible is less than animal-based food.
Plant-based and animal protein sources are complementary, but both are important.
Protein quality is lower in diets that contain less variety of protein, and especially when they are dominated by plant-based proteins.
Harvard Health states that soy, quinoa and meat are all “complete proteins”. Harvard Health says that these foods contain the amino acids the body requires.
However, other plant-based protein sources may not have all of these amino acids. Vegans and plant-based eaters must ensure that they consume different plant-based protein sources.
According to a study, DIAAS found that the best proteins are pork, eggs, potato, casein and egg proteins. These proteins scored higher than 100%. The DIAAS found that whey and soy protein scores were just under 100% but still very high.
A variety of plant-based protein sources, such as canola and hemp proteins, along with oats, fava beans, rice, corn, lupin, rapeseeds, fava beans, lupin, and rapeseed proteins, are not considered high quality. The study emphasizes that complementary proteins are more likely to be of higher quality.
Quinoa, a high-quality plant source (Yagi Studio/Getty Images).
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