When being vegan is not ok for my body? And why do we need protein?

Does the problem of protein supply in the diet deserve attention, what are they needed for, and are we able to produce them ourselves?

Protein functions:

  • The main structural material of cells.
  • Enzymatic catalysis (enzymes – biocatalysts enabling mild reaction)
  • Transport and storage (e.g. haemoglobin, myoglobin – oxygen transfer proteins, ferritin – iron-storage protein)
  • Mechanical-structural functions (a component of cell membranes, material supportive strengthening – collagen, elastin, a component of hair, nails, feathers)
  • Orderly movement (muscle spasms)
  • Immune protection (antibodies – highly specific proteins that recognize foreign substances)
  • Source of energy (10 – 15%)

Remember that proteins in every living organism undergo constant exchange, i.e. reconstruction, decomposition and synthesis. How often does protein exchange take place?

  • Body fluid proteins – a half-exchange period of several days
  • Structural proteins, found in connective tissues – every few months

The more biologically active a given protein is, the shorter its half-exchange period is.

  • In humans in myocardium, liver, plasma, intestine, pancreas and kidneys within about 10-20 days, half of the proteins are replaced with new, synthesized from amino acids supplied in dietary proteins.
  • The half-life (“half-life”) for muscle, skin and skeleton proteins is about 160 days. This period is the longest for connective tissue proteins, e.g. for collagen, it is estimated at about 300 days.

Half of the whole set of proteins in the human body is renewed on average within 80 days.

To replace a set of proteins, the body needs building material in the form of providing the right amino acids from food.

Athletes know this well, especially those who care about muscularity. Why?

It is the most important building element. Without proteins, growth, development of our body and tissue reconstruction, e.g. muscle tissue, will not be possible. During each workout, micro-injuries occur on our muscles and it is proteins that rebuild our muscle tissue. However, this is not their only function. They also build bones, cartilage and hair.

Even collagen is mostly made of proteins, its main component is glycine. In order for collagen to form, a whole series of complicated processes must occur. Other substances and enzymes are involved in each of these processes. Theoretically, this process should take place endogenously, however, due to various polymorphisms and needed substrates, production can be significantly hindered. In order for our body to produce collagen, glutamic acid and choline are needed, which is also mainly found in animal products. Any deficiencies at individual stages will result in reduced collagen production. This problem occurs quite often, which is why a whole army of collagen products is available on the market. Problems with collagen and glycine deficiency occur most often on a vegan diet and in addition gluten-free, in which sufficient supply of wholesome protein was not taken care of. In a short time, collagen deficiencies are not visible, but after 10-15 years, the skin condition of a person who is on a low-protein diet will be much worse than that of their equals.

Proteins are also part of the immune bodies, they are the basic component of blood, lymph and milk. It is also a carrier of some vitamins and minerals. What specific proteins does the human body need?

Each protein molecule is made up of many amino acids. Over 300 naturally occurring amino acids are currently known.

As we have already established, amino acids are the basic structural units of proteins.

Each amino acid is made up of amino (-NH 2), carboxy (-COOH), hydrogen (H) and R side chain. All these elements are covalently attached to the carbon atom. There are 20 different amino acids in proteins: they differ in structure and properties of the side chain (side chains differ in size, shape, electric charge, ability to form hydrogen bonds, and chemical reactivity).

The protein of all living organisms consists mainly of 20 amino acids, which are α-amino acids containing an asymmetric carbon atom with the L configuration (except glycine).

Amino acids can be divided into four groups: endogenous, exogenous, relatively endogenous, or exogenous. 

  • endogenous amino acids – this group includes amino acids that our body can produce. These include: alanine, glycine, asparagine, aspartic acid, glutamine, glutamic acid, proline, serine,
  • essential amino acids – our body cannot produce them by itself and we must provide them with food and supplements. These include lysine, methionine, leucine, isoleucine, valine, threonine, phenylalanine, tryptophan.
  • relatively endogenous amino acids – they arise in the body from exogenous amino acids, these are: tyrosine (formed from phenylalanine), cysteine ​​(formed from methionine)
  • relatively exogenous amino acids – the body produces them in small amounts: histidine, arginine.

The division of amino acids due to polarity:

  • non-polar ( uncharged) – the hydrophobic nature of glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, proline
  • polar(charged – hydrophilic character serine, threonine, cysteine, tyrosine, asparagine, glutamine, aspartic acid, glutamic acid arginine, histidine. 

Division depending on the number of amino and carboxyl groups:

  • monoamine carboxylic (neutral), glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, tryptophan,
  • monoamine dicarboxylic acid (acid), aspartic acid, acid
  • glutiniclysine, arginine, histidine.

Division of amino acids due to b femoral:

  • sulfuric (cysteine, cystine, methionine)
  • with a hydroxyl group (serine, threonine)
  • aromatic (tyrosine, phenylalanine, tryptophan)
  • hydrophobic (valine, leucine, isoleucine)

Nutritional value of proteins

We are talking about the nutritional value of protein and the biological value of protein (this value on people or animals).

The nutritional value of protein results from its amino acid composition and depends on the amount and mutual proportions of exogenous amino acids contained in a given protein and the digestibility of the protein, i.e. the degree of release and absorption of amino acids during the digestive process in the digestive tract (Liebig’s barrel). An exogenous limiting amino acid, which is the least relative to the amount required for protein biosynthesis and which limits the use of other amino acids. So not the one that has the least in a given protein, but the one which is the least in relation to the body’s needs. As a rule, vegetable proteins are poorer, only some plant products, e.g. soy, can be 100% meat substitutes. Animal proteins are usually more digestible than plant ones. Protein digestibility is measured as a percentage, it is the ratio of the amount digested and absorbed to the consumed.

Protein nutrition measures. WAO Limiting Amino Acid Index (CS – chemical score), which is a comparison of the amino acid composition of the tested protein with the standard (egg protein or FAO standard), finding the amino acid that is the least relative to the standard and we express it in %. This indicator does not take into account digestibility.

The biological value of WBB (BV – biological value). It is a measure of the effectiveness of meeting the building needs of the animal body. Unfortunately, in all these classifications, plant proteins fall much less than animal ones. That is why on a vegetarian and vegan diet it is very important to take care of wholesome protein. 

The basic source of protein for humans is food. The best for our body will be wholesome protein. They contain exogenous amino acids in their composition. Such a protein will also be for us the best digestible and nutritious for the body. Their sources are: 

  • Eggs
  • Poultry
  • Beef
  • Fish
  • Seafood

As we already know, there are also partly defective proteins. They contain essential amino acids, but at least one of them is not enough. 

Such protein contains:

  • Legumes
  • Whole wheat bread
  • Groats
  • Cereals
  • Nuts

The problem of protein supply on a vegan diet is actually a challenge. Tofu, soy products, legumes, mushrooms and nuts are considered sources of vegan protein. You also have to remember that it is not just about providing some protein, but many different amino acids. Is this impossible? Of course not! We can provide the body with a full package of needed amino acids also on a vegan diet, how to do it in practice?

How to combine plant products to get a full aminogram?

To obtain a full-fledged amino acid profile, the principle of combining products according to the category:

  • Leguminous vegetables: beans, lentils, peas, chickpeas is used.
  • Cereals and pseudocereals: bread, pasta, rice, rye, oatmeal, buckwheat, quinoa, millet.
  • Nuts and seeds: peanuts, cashews, walnuts, almonds, sunflower, sesame, pumpkin seeds.
  • Soy products: soy milk, tofu, tempeh.

Here is an example of favorable connections with protein products in meals:

  • beans or chickpeas with pasta whole grain
  • brown rice with lentils
  • vegetables with pasta whole grain and sunflower seeds or pumpkin
  • wheat bread with peanut butter
  • lentil soup with potatoes
  • tofu with vegetables and rice
  • milk soy and oatmeal
  • chickpeas vegetables
  • quinoa with broccoli 
  • bread sandwiches with hummus
  • breadcrumbs with whole grain bread
  • buckwheat with chickpeas and pumpkin seeds

A varied diet is a sufficient way to provide all amino acids – both in traditional and vegan diets. However, the more restrictions we put on the diet, the harder it is to take care of the supply of the full protein package and the more effort we should make to see if we really lack anything.

Often, by combining two types of protein in one meal, we get wholesome food in terms of amino acid composition, but this does not happen from the machine. Most plant-based proteins do not contain essential amino acids, e.g. cereal products are low in lysine, legumes lack methionine. But by combining cereal products with legumes, we get high-quality protein. Particularly important amino acids that we should pay attention to are methionine (critical to methylation, i.e. the functioning of the body) and lysine, often called limiting amino acids, because they are slightly less in plant products. Most vegetables, legumes, seeds and cereals contain relatively few of these amino acids. The exceptions are soy and quinoa, which are primarily rich in methionine. A better source of methionine is whole grains that should be present daily in the plant diet. When it comes to lysine, seeds, nuts and seeds will be a good source. To provide a full pool of amino acids it is worth combining these products in one meal, but it is not necessary if they appear on the menu throughout the day.

As you can see above, it is possible to provide all amino acids on plant diets, but you have to do it wisely. If for some reason we cannot eat pods or nuts (thyroid problems, histamine intolerance, allergies, etc.), it is not possible for us to meet the body’s meatless diet.

I often come across the argument: But on a raw, vegetable diet, I cured the thyroid gland and many diseases ….

Everything is correct. Just think that you gave up not only sources of full-value protein, but also rolls, cakes, cheeses, processed products (containing huge amounts of toxic substances), pizzas, etc. This allowed you to cleanse the body of toxins and reset the system to factory settings. For many people, this can be a way to get rid of diseases, but a raw diet, in this case, is a kind of healing fast. If you stop at this stop for many years or permanently, deficiencies of protein and other substances will increase. You will not notice it quickly, it is only after a few years that it turns out that in the number of wrinkles you have overtaken your peers, and it will only be the tip of the iceberg.

The issue of the harmful effects of meat consumption is often misinterpreted. Each time the test results depend on the intention of the researcher. If someone wants to prove the harmfulness of eating meat, they will reach for tests in which the effects of consuming bacon, sausages, etc. were checked. It is analogous to prove that the vegetable diet is unhealthy. It is always important what product we choose, whether from eco production, free from pesticides and antibiotics, whether it is a highly processed product, etc. From the point of view of our health, the most important is whether our diet is varied and balanced. This applies to both plant and traditional diets.

You can read more about it here:


and here:


The path of balance is difficult .. often it is much easier to enter the so-called ism (neologism defining an equal type of clinging to a given ideology). When we are strongly attached to one path, it is easier for us not to succumb to temptation, and food temptations are among the most difficult to overcome …

Many people, also now considered by some as the authority, can confidently claim that the topic of protein is overrated and not very significant. Unfortunately, when we look closely at how mitochondria, or power plants, work in our cells, and how it works the methylation cycle turns out that the importance of protein in our diet is fundamental!


Anila Popławska



Ciborowska, A. Rudnicka Dietetyka. Nutrition of a Healthy and Sick Man PZWL 2014

T.Colin Campbell Modern principles of nutrition, Galaxy 2016Ś Śl

Scientific editors Daniel, Artur Mamcarz Medycyna Lifestyle, PZWL 2018

http://zb.eco.pl/publication/aminokwasy-w-zywienie-wegetarianskim- p1532l1


http://mentalhealthdaily.com/2015/03/21/undermethylation-vs-overmethylation- causes-symptoms-treatments /