protein quality

Understanding protein quality in simple terms

Proteins are made up of amino acids linked together in a very complicated three-dimensional structure. Proteins are the building blocks of our body. Every cell in our body has protein and protein has several important functions to perform. Proteins play the role of major structural component of muscle and other tissues in our body, they are also needed to synthesize hormones, enzymes and haemoglobin.

When we are looking for dietary protein what we need to look for in a protein is that the food protein should look like our body protein in composition as much as possible and it should be in sufficient amount.

Amino acids

Proteins are made out of chains of amino acids.  The number and type of amino acids in different proteins is different and they are arranged in different order. There are hundreds of amino acids in nature but there are about 20 which are found in living things. And these twenty are the ones which are important to us.

Amino acids can be divided into three classes based on their necessity by our body. 

  • Essential amino acids,
  • Non-essential amino acids
  • And conditionally essential amino acids.

Essential amino acids cannot be synthesized in the body and have to be provided on a daily basis by our diet. And those that can be synthesized by our body from other dietary components are referred to as non-essential amino acids, we can get by even if our diet does not provide them. Conditional essential amino acids are actually non-essential but in certain conditions such as illness they become essential.

What are complete proteins?

Protein is the only macronutrient that contains nitrogen and is made up of amino acids. Some literature says there are nine and some say that there are ten essential amino acids. A complete protein is a protein that contains all the essential amino acids and in the proportion they appear in human protein or as close to human protein as possible. Those which do not meet these conditions are called incomplete proteins.

A complete protein is also generally described as good quality protein. The quality of protein is measured by looking at these factors

  • Essential amino acid composition,
  • Digestibility
  • Bioavailability of amino acids
  • Relevance to human beings.

To determine whether a protein is complete or not several methods exist such as protein efficiency ratio (PER), biological value (BV), net protein utilization (NPU) and protein digestibility corrected amino acid score (PDCAAS). These tests will tell us whether the protein is having all the essential amino acids in required amounts, whether it is digestible and available to our body for absorption and utilization. In simple word whether it is of good quality of not.

Dietary sources of complete and incomplete proteins

Eggs, fish, poultry, milk and milk products, beef, pork and other proteins of animal origin are complete proteins. They contain all the essential amino acids in the required proportion and are digestible. Some plant proteins also do meet the criteria of a complete proteins for example soyabeans and soy products, quinoa, amaranth etc. 

Proteins from plant sources such as wheat, rice, corn, fruits and vegetables are considered to be incomplete proteins or not so good quality protein. That’s because they do not have all the essential amino acids or in in required amounts. Plant food sources also have lower amounts of proteins compared to non-vegetarian sources.

How to get complete proteins from incomplete proteins?

The essential amino acids lacking/limiting in different plant proteins are different. Therefore, we can strategically combine plant proteins to make them complete proteins. For example, the amino acid which is limiting in cereals is lysine. Lysine is present in legumes and methionine is missing in legumes which is present in cereals. Combine cereals and legumes in a meal and we get complete protein.

Vegetarians do not consume animal proteins at all or if they do it is probably only dairy products. This restricts not only the amount of protein, because animal food sources have more protein, but also the quality of protein is not good.

Role of soya protein  

Soyabean and soya products are rich sources of protein. Soya protein is a plant protein but is considered to be on par with animal protein when it comes to quality of protein. Vegetarians and vegans are always on the look out for plant protein sources which provide sufficient amounts of protein as well as good quality protein. Generally, by mixing complementing proteins we can get a complete protein from plant sources but plant proteins such as soya beans and soya products on their own are complete proteins.

VegPro products are rich source of protein because they have 52 % and the protein is a complete protein. Those looking for complete plant protein can find that in VegPro products which are made from defatted soya flour.

Incorporate VegPro products into your diet regularly to meet protein requirements as they are a rich sources of complete plant protein.

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