This has got to be the most frequently asked question about veganism: Where do vegans get protein from? Let me spoil it right away: vegans get their protein from food. But let us take a deep dive into this insane fear of protein deficiency among vegans. We will look at the biochemistry of what proteins actually are and put into perspective how much protein adults really need.
What is a protein?
Before we start exploring where vegans get their protein or how much protein a human being even requires, we should take a step back. People love talking about protein sources and calculating how many grams they would need according to their body weight or fitness goals. Very rarely do they ask what a protein even is.
If we speak in very broad categories, protein is one of the three main macronutrients alongside carbohydrates and fat. Food labels usually list all three, because they are the nutrients that provide the actual energy, in other words the calories, in any food product. Apart from these, you will also usually find fibre and salt in the general nutritional information.
The macronutrient information on food labels usually refers to 100 g of the product. For a 100 g block of firm tofu, the label may for example state 13 g of protein. What is important to know is that these numbers are always estimates. Scientists cannot directly measure the actual protein content of food items, but instead calculate it based on the nitrogen content of each item.
Since neither water, fibre nor the other two macronutrients contain nitrogen, its presence is a clear indicator of protein. The nitrogen itself is part of the single amino acids that make up any protein. Apart from nitrogen, all amino acids also contain carbon, hydrogen and oxygen. Two of the 21 amino acids, cysteine and methionine, also contain sulfur.
Every protein is made up of chains of amino acids. Depending on the purpose of the protein, these chains can vary a lot in length as well as in their exact composition and sequence of amino acids.
We don’t need protein – We need amino acids
There are 20 amino acids in total that are used to build proteins in living organisms. These amino acids can be divided into three categories: essential, non essential and conditionally essential. Essential amino acids are those that the body cannot produce on its own. This means they must be obtained through food.
The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Non essential amino acids can be produced by the body itself. They are alanine, asparagine, aspartic acid, glutamic acid and serine.
Conditionally essential amino acids are usually produced by the body, but may need to be obtained through food under certain conditions such as illness or stress. These include
arginine, cysteine, glutamine, glycine, proline and tyrosine.
Our body needs all 20 of these amino acids in order to build protein. The word build is the key word here, because this is exactly what most people do not realise. When we eat food that contains protein, our body does not simply take that protein and place it where it is needed.
Instead, it breaks all the protein down into its individual amino acids and then pieces them together again like a puzzle to build exactly the protein it needs at that moment. When people dismiss plant protein, they often argue that animal protein is better for the human body because it is more similar to human protein and therefore more readily available.
While the idea of similarity is broadly correct, the conclusion people draw from it is not. Whether we eat animal protein or plant protein, the body does not simply take it over as it is. It breaks it down into amino acids and uses those building blocks to create the proteins it actually needs.
So how much protein do we need?
Since it is already difficult enough to measure whole protein, we will not literally talk about grams or daltons of amino acids. For the sake of simplicity, we will stick to the language that is commonly used. So how much protein do humans need? In order to answer that, we first need to look at what exactly we need protein for.
Protein is mainly associated with growth, and many people think of muscles first. But growth in this context does not just mean muscle growth. Protein is needed to build and maintain tissue throughout the body, including muscles, organs, skin and connective tissue, and it also plays an important role in many enzymes and hormones.
As adult human beings, however, growth is not really much of a goal anymore. Apart from the individual desire to build more muscle mass, most processes in the body are about maintenance rather than growth. In fact, unwanted growth, such as tumors or other excess tissue, is usually a mild to severe health concern.
The time in our lives when it is really all about growth is the very beginning, especially during the first year of life, when growth is faster than at any other stage. Newborn babies in particular have to grow fast in order to become more resilient and increase their chances of long term survival and strength.
It is therefore very interesting to look at how much protein newborn babies need and then move on to children, teenagers and eventually fully grown adults.
Our very first growth – The protein content in breast milk
The first food of newborn human babies, as intended by nature, is mother’s milk. The milk a mother produces for her own child is one of the most fascinating nutritional substances in the world. Human breast milk is tailored to the needs of the nursing infant. There is evidence that the baby’s saliva interacts with the mother’s breast during feeding, allowing the mother’s body to respond to the baby’s current needs.
Milk composition can change over time and even during a single feeding. When a woman nurses two children of different ages, for example a newborn and an older infant, each breast can indeed produce milk with slightly different compositions to meet the needs of each child.
So what about protein? The protein content of human breast milk is surprisingly low. On average, it contains roughly 1 to 1.3 grams of protein per 100 millilitres, which corresponds to about 5 to 7 percent of total energy. In colostrum, the first milk produced after birth, the protein content is usually at its highest.
As the baby grows, the protein content goes down. A fully breastfed baby usually drinks around 700 to 800 ml of milk per day. If human breast milk contains around 1 to 1.3 g of protein per 100 ml, that adds up to only around 7 to 10 g of protein per day.
At the stage of maximum growth, when growth is needed more than ever, this range of daily protein intake is enough to thrive. With adults, protein requirements are often calculated per kilogram of body weight, so let us do the same for babies to make the comparison easier.
At around one month of age, with an average body weight of about 4.5 kg (10 lbs), this equals roughly 1.7 to 2.2 g of protein per kilogram of body weight. At three months, with a body weight of around 6 kg (13.2 lbs), it drops to about 1.25 to 1.6 g/kg.
By six months, at around 7.5 kg (16.5 lbs), it is about 1.0 to 1.3 g/kg. At around twelve months, with an average body weight of roughly 9.5 kg (21 lbs), it drops further to about 0.8 to 1.0 g/kg. And here we are entering the range that is commonly considered the protein requirement for fully grown adults (0.8 g/kg).
If protein requirements are already decreasing during a phase of life in which we are still growing, that is infancy and childhood, why do people assume that a fully grown adult would still need the same amount of newly supplied protein through food?
Children stock up and adults recycle
When a child grows, it literally needs to create new material to make bones, tendons and muscles longer, new tissue to increase the size of each organ, and new skin to cover all of this new body mass. During growth, the human body therefore constantly needs new building blocks, and proteins, or rather amino acids, play a major role in this.
However, protein does not work like a brick that has a fixed long term place in a house. It is highly dynamic and is constantly being broken down and rebuilt in different ways in the human body. Even a muscle that appears steady in its size is constantly replacing proteins. The human body, from that perspective, is a super recycle machine.
Of course, this is not an adult only phenomenon. Even in infants and children, proteins are constantly recycled, but in order to support all that new growth, more amino acids are needed. Adults can manage all that recycling with fewer newly added amino acids. That does not mean, of course, that we can rely on recycling alone.
Recycling is highly efficient, but not perfect. Some amino acids are always used for energy or converted into other substances, and their nitrogen is eventually excreted as urea in the urine. This is why even adults need a regular supply of new amino acids through food.
The unreasonable fear of protein deficiency
Unlike fat or carbohydrates or, behold, the actually super important fibre, protein has been hyped for many years now. For some reason, there is such a widespread fear of protein deficiency, whereas by comparison almost nobody worries about not getting enough carbs, fats, fibre or even vitamins and minerals.
And yet, the reality is the total opposite. Not getting enough carbs leaves us low in energy. Not getting enough essential fatty acids can cause real health problems. A deficiency in certain vitamins and minerals is incredibly common in modern societies and can result in all sorts of issues. However, a protein deficiency simply is not a thing.
It is not biologically impossible, of course, but for almost everyone who has regular access to food, any food, there are enough amino acids coming in to replenish what is lost through recycling and energy use. Vegans never have to worry about protein.
I could of course list all those high protein vegan foods, like you might see in any other article on this topic, but it is not even needed. You do not need to worry about getting enough protein, end of story.
