Protein: The Building Blocks of Life

What are proteins?

We all have some sort of idea about proteins being important. Debates about veganism or vegetarianism often involve the question of getting enough protein. Protein powder is a well-known supplement for people trying to build out muscle. But most people do not know much about protein other than that they need it. In this blog, we will unpack all you could ever want to know about protein so read on.

Proteins are frequently called the building blocks of life because they are found everywhere: in our cells, bones, muscles, blood, hormones, enzymes and more. It is thanks to proteins that our body has any sort of structure to it. To get a bit more technical, a protein is a complex structure that consists of either just a few or up to thousands of amino acids, depending on what structure this protein is supporting. When protein enters our body, it is mainly used to build new tissue, hormones, cells and provide energy.

Alongside carbohydrates and lipids, proteins are one of the three macromolecules that provide energy to our body. We require large amounts of macromolecules to sustain life. Each gram of protein provides 4 calories of energy. Proteins are also one of the most common components in our body, as 15% of our body weight is made up of protein. This may initially not sound a lot. But if we consider that 60% is water, it is almost half of the solid body mass. The other part is fat (20% - depending on gender and activity level) and minerals (5%).


What are amino acids?

If proteins are the building blocks of life, amino acids are the building blocks of proteins. Amino acids are small building blocks that are put together in special order of bonds or structures to make proteins. There are 20 different amino acids, 9 of which are considered “essential amino acids.” The catch with these 9 essentials is that our body cannot produce them from scratch, so they must be supplied from our diet. The nine essential amino acids are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. If our bodies are lacking in any one of these 9 essential amino acids is insufficient, protein synthesis, aka the building of new cells, hormones or tissues, will be compromised. So it is really important to make sure you are getting the right amount and quality of proteins in your diet.


What do proteins do in our bodies?

The better question would be “what don’t do proteins in our body?” They are involved in so many processes in our bodies that the comprehensive list would be too long, so here are some of the highlights:

Cell growth: There is hardly a process in the body where proteins are not involved. For example, a newborn baby consists of more than 10 trillion body cells. For the development of each of those cells, protein is required.

Enzymes and hormones: Many enzymes and hormones are proteins. Let’s take an example of an enzyme: lactase is the enzyme that splits up lactose from dairy products in the intestine to make it available to our body. If someone is lacking the enzyme, he is unable to digest dairy and is called “lactose intolerance”. So intolerances are basically missing enzymes, as opposed to allergies, which are a problem with the immune system.


How do we get proteins?

There are two main protein providers: diet and the body. Our body has a very efficient recycling system to gain new proteins from breaking down old cells. This indispensable process is constantly occurring and necessary to maintain health of all our tissues and organs functional.

Protein in food: There are endless discussions about the amount and type of protein in our diet. Since Dr. Atkins kicked of the low carb avalanche, every foodie out there knows that proteins can be found in animal products like meat, eggs, fish, and dairy or vegetable products like legumes, beans or soy. But it’s not as simple as knowing whether food has protein in it. There are different levels of protein quality based on factors like composition and digestibility.


What is protein quality?

1. Composition:

As we have mentioned, the 9 essential amino acids must come from our food. A food that contains all 9 essential amino acids is called a “complete protein”. All animal foods contain the 9 essential amino acids. Plant foods are usually missing one or more, so they are called “incomplete proteins”. The missing amino acid is the “limiting amino acid”. For example, beans are low in methionine and cysteine, so these two are the limiting amino acids.

This is one of the main arguments meat eaters make against vegan or vegetarian diets. But that is an incomplete understanding of how our body uses protein from our diets. It is definitely possible to get complete protein needs from plants, so long as they are strategically combined to cover all the 9 essential amino acids together.

One study (1) analysed the amino acid composition of more than 1200 plant-based foods to identify the most balanced and the most unbalanced Indispensable Amino Acid (IAA) patterns. The following two tables are the outcome of this study. The first table shows foods with the most balanced IAA pattern and the second one foods with the most imbalanced IAA patterns. Most of these might not be the first foods that come to mind when thinking of protein sources, but that is further proof of how much protein is misunderstood. The most efficient plant pairings found were sweet corn/tomatoes, apple/coconut, and sweet corn/cherry. Who would have thought corn and tomatoes were such protein all-stars?

Top single plant-based foods with the most balanced IAA patterns resulting in the highest IAA efficiencies:

Wheat based formulated nuts

Wheat germ


Pickle relish








Top single plant-based foods with the most unbalanced IAA pattern resulting in the lowest IAA efficiencies.


IAAs most in excess (+) or deficient (−)

Macadamia nuts

(−) lysine; (−) methionine+cysteine

Corn-based breakfast cereals

(−) lysine; (+) leucine

Degermed cornmeal

(−) lysine; (+) leucine

Wakame seaweed

(+) valine; (−) histidine; (−) lysine

Peeled cucumber

(+) tryptophan; (−) histidine

Prepared mustard

(−) tryptophan

Peas with edible pods

(+) valine; (−) histidine


(+) tryptophan; (−) methionine+cysteine


(−) tryptophan; (−) methionine+cysteine


(−) lysine

Brazil nuts

(+) methionine+cysteine


  1. Digestibility:

The second important factor to determine the quality of a protein is its digestibility, or how well our bodies can break down the protein taken with food and put it to use. There are different methods used to test the digestibility of a protein. Animal protein can be highly digested (90%), legumes also do have a high digestibility (70-80%), some grains and other vegetable product do have lower rates (60-90%).

Digestibility in protein is so important that is has its own rating: the Protein Digestibility Corrected Amino Acid Score (PDCAAS) is a score that combines different measurements to determine the quality of protein. It includes the amino acid composition as well as digestibility. PDCAAS is the currently most accepted and widely used method.  

Thanks to its composition and digestibility, spirulina is one of the leading sources of plant-based protein. While most plants are considered incomplete proteins, spirulina is a notable exception. This blue algae has an impressive nutrient portfolio, as it contains all the 9 essential amino acids required to consider it a complete protein, as well as many other important vitamins and minerals. It also is easier to digest than many other sources of protein. A study (2) concluded that spirulina has a high digestibility (83-84%) because it lacks cellulose cell walls and therefore does not require special processing in order to become digestible.


Recommended protein intake:

The general recommendations are about 0,8g/kg body weight per day. Different circumstances require higher quantities such as pregnancy or lactation. Athletes also need a higher level of protein.

There are innumerable topics in the world of nutrition, health, and wellness where protein is a central element. Just to name a few: protein and its role in endurance sports, in bodybuilding, in weight loss and as well in diseases, like chronic kidney disease. Due to the amount of research and opinions that exist in each one of these topics, they cannot be discussed in detail here. But the consensus among these studies is that getting sufficient protein without overdoing it is key to vitality. A well balanced, mainly plant-based diet is the most recommended form of nutrition nowadays. This will give you a healthy balance between macro and micronutrients is the best way to cover the body’s needs and support an optimal functioning.


Bottom line:

Proteins are one of the three macromolecules and are the building blocks of life. They are made of amino acids, nine of which are essential and not able to be produced by our body. This means they have to be taken with food. Proteins have a long list of responsibilities in our bodies, starting from cell growth to oxygen supply, production of hormones and much more. We can take protein with food. Different sources of protein offer different qualities. Animal food has a higher protein concentration than plant-based food, but plant-based foods can be combined wisely to offer the same protein quantities.