In recent years, the growing need to pay attention to diet has led to an increase in the consumption of vegetable proteins compared to animal ones. This to the point of seeing the clear increase in people who choose to prefer a vegetarian and vegan diet. In this regard, proteins were the first target of this change.
In nature, we can find these molecules both in foods of animal and vegetable origin. What distinguishes them is the ability of our body to use these molecules, an aspect that allows them to be classified according to their biological value.
Although they present some aspects of inferiority compared to molecules of animal origin, vegetable proteins also bring many benefits. Let’s get to know them better and thoroughly!
Proteins: what they are
Proteins represent a large group of organic compounds made up of sequences of building blocks known as amino acids. These bricks are linked together through peptide bonds in very different ways and for varying lengths.
The result is an infinite series of possible combinations and, consequently, of protein molecules. Proteins are part, together with fats and sugars, of that category of biological molecules known, in the food sector, as macronutrients.
These are taken by the body only with the diet as some of these amino acids we are not able to biosynthesize them.
Therefore, it is important to constantly include this category of molecules in our diet.
Proteins, as mentioned, can be found both in foods of animal and vegetable origin. There are clearly differences between the two types of proteins. Just think that animal proteins commonly tend to have all 20 amino acids. Instead, often the vegetable ones are deficient in some.
Check out our complete protein guide.
Differences between animal and vegetable proteins
A parameter that is commonly used to distinguish between animal and vegetable proteins is their biological value.
This parameter refers to the ability of a protein molecule to satisfy the body’s metabolic needs for total amino acids and essential amino acids.
It is also influenced by the digestibility of the protein, i.e. by the percentage of protein that is digested and by the corresponding quantity of amino acids present in the gastrointestinal tract.
All this always without losing sight of the percentage of essential amino acids present in this fraction. So:
- Animal proteins have all 20 amino acids, including an adequate amount of the essentials. For this reason they are defined as high biological value.
- Vegetable proteins have partly non-digestible proteins and in any case often lack some amino acids, especially the essential ones. This causes them to be considered of low biological value.
- A substantial difference between animal and vegetable proteins is their digestibility. To define this aspect, the CD is considered. It indicates the percentage of food that is actually absorbed and corresponds to the ratio between ingested and absorbed nitrogen. For example, the egg is the food that has the highest CD among all protein foods. Conversely, plant foods have medium-low coefficients.
In nature, there is no distinction between animal or vegetable proteins. What distinguishes this category of molecules is the food from which they are obtained. In fact, there may commonly exist protein molecules that are found in both animal and vegetable foods.
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As can be easily understood, these proteins are obtained from foods of plant origin, among which are:
- Algae (primarily spirulina).
- Cereals and processes obtained from cereals (the main ones being wheat muscle and seitan).
- Dried fruit (walnuts, pecans, Brazilian nuts, hazelnuts, almonds, pine nuts but also legumes included in the category of dried fruits such as cashews and peanuts).
- Legumes (beans, chickpeas, lentils, broad beans, peas).
- Oilseeds (sesame, hemp, chia, flax, sunflower).
- Soy (for example beans and edamame) and derivatives obtained from the processing of this legume (tofu, tempeh, miso, tamari shoyu).
In small quantities, proteins can also be obtained by consuming fruits and vegetables but in a negligible fraction of a person’s nutritional needs.
Vegetable proteins: quality and biological value
From a qualitative point of view, there are no substantial differences between animal and vegetable proteins. What changes is their biological value. This concept, generally indicated by the letters VB, means the amount of nitrogen actually absorbed and used by the body.
This value is considered net of urinary and faecal losses. The biological value refers to that of the food which is considered as the best quality protein source, ie the egg, which has a BV equal to 100%. What does this mean?
It is understood that in order to obtain protein completeness by exclusively taking foods of plant origin, it is necessary to pay some attention.
For example, you should always associate cereals and legumes. In a nutshell, supporting compliance with a Mediterranean diet based on pasta or legume soups makes it possible to compensate for the low biological value of the proteins in these foods.
Amino acid deficiency
Therefore, in general, vegetable proteins should be considered qualitatively less complete than animal proteins.
This is essentially due to the lower biological value linked to the lack of essential amino acids.
For example, if we consider cereals, these would be especially deficient in tryptophan and lysine. In fact, these amino acids have a very important biological role as they are directly involved in the biosynthesis of vitamin B3.
Conversely, legumes have proteins rich in these amino acids but deficient in methionine and cysteine. Therefore, their consumption as the only protein source would risk causing reduced growth of hair, hair and nails.
This is why the combination of foods, especially if you consume only foods of plant origin, becomes fundamental.
Clearly this combination does not necessarily have to be made in the same meal (for example with pasta and legumes). It would be enough to add the “deficient” vegetable source in the next meal to ensure optimal needs. In biology, this phenomenon is known as protein complementation.
Vegetable and animal proteins: the daily protein dose
There is a precise balance between proteins of animal and vegetable origin which should be ingested in the diet. This is established by the Reference Intake Levels of Nutrients and Energy for the Italian population (LARN).
In fact, according to LARN, proteins must supply 15-20% of the total daily energy, 2/3 of these proteins must derive from products of animal origin, 1/3 from products of vegetable origin.
Therefore, imagining a person who takes about 1500 Kcal daily, he should not exceed 70 g of protein. Of these, 23-24g should come from foods of plant origin.
Sources of vegetable proteins
There are many vegetable protein sources. However, an important clarification needs to be made. Very often the protein content is referred to the product before cooking.
In the case of plant foods, this process significantly alters the protein content in 100 grams of food. Just think of legumes.
In this case, although dry they have a protein content equal to or greater than 20g/100g, cooking drastically reduces it by more than 50%.
At the extreme, we can get to canned peas which see a reduction in protein in 100g of product from 21.7g to 5.1g (reduction of 76.5%!).
All this while keeping the intake of other macronutrients such as fats and, above all, sugars unchanged.
It is what is considered the vegetable protein source par excellence. In this regard, it must be said that dried legumes have a protein content similar to that of meat (around 25-30%).
Despite this, this is significantly reduced in fresh ones, in soaked ones and, even more, in cooked ones. The limiting amino acids in this category of foods are cysteine and methionine, i.e. two molecules belonging to the category of sulfur amino acids.
In fact, they owe this name to the fact that they have sulfur in their chemical structure. belong to you:
- Soy (although we will see later that there are differences).
- Lupins, but also peanuts and cashews, although the latter are considered on a par with dried fruit.
Discover our guide on legumes.
Cereals are foods known more for their carbohydrate intake than for their protein content. Despite this, they are able to provide a moderate amount of protein. It is good to consume especially the wholemeal ones.
In fact, part of the protein is stored right in the bran. This category includes bread, pasta and rice but also barley, spelt, oats, millet and rye.
Among the most protein cereals are:
- avena (16.4g of protein).
- Rye (16g).
- Farro (15,1g).
Vegetable proteins: derivatives of cereals (wheat muscle, seitan and others)
Some processes plan to make the most of the protein part of the cereal, generating foods that are much richer in protein than the original cereal.
An example above all is seitan. This food involves a wheat processing aimed at extracting the protein component (especially the…