Differences between vegetable protein and animal protein

Plant foods proteins and animal foods proteins


Why are animal protein and plant protein different?

The most noticeable difference between animal and plant protein source is its nutritional quality.

Animal proteins contain all the essential amino acids, whereas plant foods, have to be combined to get to have all the essential amino acids.

However, this is not the only difference.

If we take into account factors such as absorption and availability of these proteins in our body, the animal protein is better assimilated than vegetable protein.

Absorption of animal protein and vegetable protein

vegetarian protein-rich food
Foods rich in protein in an ovolactovegetarian diet: vegetables, eggs, dried fruits and dairy.

Animal protein is better absorbed than plant protein, or, what is the same, vegetable protein has less absorption than that one from animal origin.

About 90% of animal protein is absorbed, while vegetable absorption attains about 60 or 70%.

Why does protein absorption depend on?

This is mainly due to the following factors:

  • Molecule structure: animal and vegetable proteins have a different structure, and our body can easily assimilate the animal one.
  • Interactions with fats, nucleic acids, fiber: These components present in the food can reduce the absorption of proteins.
  • Antinutritional factors: as enzyme inhibitors present in some foods (eg trypsin inhibitors in raw vegetables) or tannins (they combine with the proteins, preventing their absorption).
  • Cooking: Proper cooking helps to better digest food proteins. Raw or undercooked vegetables can be indigestible
  • Diseases: Some diseases may condition the absorption of amino acids: trypsinogen deficiency, Hartnup’s syndrome, cystinuria, cystic fibrosis…

The required amount of protein intake depends on their origin. For example, to meet the same protein needs, you should consume more in case of ingesting plant protein.

Digestibility of animal and plant proteins

Protein digestibility refers to how much of absorbed protein is consumed by the organism. In terms of nutrition it is called coefficient of net protein utilization (NPU), and scientifically, this value is measured by subtracting the ingested nitrogen from fecal nitrogen.

Digestibility is related to the presence of essential amino acids: If food has a limiting amino acid, or conversely, if it contains all the essential amino acids.

Animal foods are more digestible because they contain all the essential amino acids (and has no limiting amino acids), which improves the utilization of these components so that the body can manufacture its own proteins.

Animal proteins have a very high digestibility: 98% in the egg (the largest). The use of plant proteins is 85%, since they lack some essential amino acid (limiting amino acids).

Biological value of proteins and their combination

The biological value of a protein is defined as the proportion of absorbed protein that is used by the body.

For a protein to be used by the body, it is necessary that the protein contains all essential amino acids in the required proportions:

  • Animal proteins are of high biological value because they contain all the essential amino acids. The food with the highest biological value is egg protein or albumin (value 1, the maximum reference used), followed by milk protein or casein (value 0.9). Meat and fish have a biological value between 0.75 and 0.8.
  • Vegetable proteins are of lower quality because they contain essential amino acids but some of them in small amounts (which is termed limiting amino acid). Wheat protein has a biological value of 0.5. For this reason we must combine plant foods to avoid these shortcomings, actually getting nutritious dishes in all aspects, not just at the protein level.


Legumes are deficient in methionine


Nuts are deficient in lysine


Grains are deficient in lysine
Chickpea with couscousThe combination of food causes all amino acids to be provided.

The table shows how the combination of two plant foods manages to obtain proteins of higher biological value. * More information: Combining proteins

Foods of animal and vegetable origin

Despite all the above considerations, we must not forget the nutritional value of food. The plant foods are absolutely necessary for health because they provide:

Animal foods, in general, should be consumed in moderate doses more mainly because they provide:

Diferencias entre la proteína animal y vegetal, vegetarianismo

Summary of the differences between animal and vegetable protein explained above, prepared by Botanical-online.

Conclusion: A balanced diet

Vegetable protein has disadvantages with respect to animal protein, because it is more difficult to assimilate for the body, and also does not provide all essential amino acids. Nutritionally is not as complete and not as well absorbed as animal protein, which requires us to combine plant foods with each other to get the right amount of protein.

The combination of vegetable proteins can not only help solve some of the above drawbacks, but may also be a very nutritive mixture.

However, people with special protein needs are highly recommended to consume foods rich in animal protein, to avoid the risk of major nutritional deficiencies. For example, a lacto-ovo-balanced vegetarian diet can be very healthy.

In case of choosing a vegetarian diet, the peculiar characteristics of the vegetable protein force us to choose plant foods more carefully, combine them properly in a varied way to meet our protein needs.

We can live perfectly without meat or fish, although abstaining from eating this kind of food requires a greater commitment when planning and preparing weekly menus.

* Go on reading: Protein combinations, limiting amino acids,

punto rojo More information on essential fatty acids

This article was endorsed by Elisenda Carballido - Dietitian nutritionist. Postgraduate in Phytotherapy and master in Nutrition and Metabolism.
Written by Editorial Botanical-online team in charge of content writing

11 September, 2022

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