Plant proteins: All you need to know

By January 28, 2016Blog
Beans and lentils

This question vegetarians hear regularly is Where do you get your protein? This is an extremely important question in regard to strict vegetarians who exclude all animal products, including dairy, in their diet. All you need to know (or at least pretty much) about plant proteins including smart combinations is in this post. This blog is not meant exclusively for vegans though. I hope it is interesting also for non-vegetarians who want to cut on animal protein.

One of the potential dangers of long-term strict vegetarian diet is a chronic lack of protein. This can lead to weakening of the immune system, the destruction of muscle and bone tissue, and in severe cases to diseases such as senility and degeneration.

What is a complete protein?

The utility of the protein is determined by two factors – its digestibility and amino acid content. Generally, animal proteins have the digestibility index of 90-99%, plant proteins – 70-90%. Corn protein, for example, is absorbed very poorly, but the digestibility of soy-bean is very close to that of animal protein.

All proteins are composed of amino acids. Amino acids can be considered little building blocks. To construct a protein in the human body 20 different building blocks or amino acids must be used. Nine of them are essential. This means that they must be ingested with the food. Our body cannot produce them. Essential acids include phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine and histidine.

Protein synthesis in the human body occurs in an interesting way. First, a protein that we get from foods is split into amino acids. Then, as a result of complex chemical reactions, these separate amino acids are arranged in proteins needed by the body.

All animal proteins are complete, that is, they contain a complete set of essential amino acids necessary for optimal maintenance of protein synthesis in the human body. Plant proteins are generally lacking one or more essential amino acids. For example cereals lack lysine and isoleucine, and legumes lack methionine and tryptophan. However, if you combine cereals and legumes, you get a set of amino acids, which complement each other. In combination, they can become a valuable material for the synthesis of the protein that we need. Therefore vegans are recommended to consume foods that combine complementary proteins.

To determine the quality of protein the so-called protein digestibility-corrected amino acid score (PDCAAS) is used world-wide. The score takes into account the amino acid composition of proteins and protein digestibility, i.e. both parameters described above. Eggs, milk and soybeans have the highest score of 1. Interestingly the meat has a lower score of about 0.9.

Soy-beans contain more protein than other legumes (and this protein is well absorbed by the human body), and they provide all the 9 essential amino acids. 100 grams of tofu contains 8-14 grams of protein. Take a look for Inspiration at my vegan tofu burgers recipe and grilled tofu recipe.

Smart combinations

If properly combined, plant foods can deliver all the essential amino acids, making sure that the protein synthesis in the human body is optimal. In principle, the main rule of the combination of plant proteins is simple: cereals are combined with legumes or nuts or seeds. Some examples of the classic combinations include:

  • Pita and falafel (chickpea croquettes)
  • Sandwich with hummus (chickpea dip)
  • Rice with lentils or beans
  • Porridge with plant “milk”
  • Lentil soup with bread

How much protein a vegan needs?

Under normal circumstances, a healthy adult should consume around 0.8 grams of protein per 1 kg of body mass per day. For example, if your weight is 60 kg, you need 60 × 0,8 = 48 gram protein per day. However, if you’re vegan, you need more protein. It is believed that vegans should consume about 25% more protein, which makes it 1 gram per 1 kg body mass. This assumption is based on the fact that the plant protein on average is digested more poorly. Thus, if you are a vegan and weigh 60 kg, you need 60 gram of protein per day.

If you doubt whether you eat enough protein, a food diary can help you to make a good estimation. Nowadays there are plenty of apps that do all the calculation for you, so you might want to try one out.

Author Lera Krasovskaya

More posts by Lera Krasovskaya

Join the discussion 2 Comments

  • Jennifer says:

    I recently became vegan 1 year ago and I have a three year old son, how can I prepare his school lunch to ensure he is getting enough protein everyday and he is also very gassy from all the veggies and beans is there a way to correct this? Thank you for this web site it’s amazing!

  • Lera Krasovskaya says:

    Dear Jeniffer,

    Raising a healthy vegan child is a true challenge. It is not impossible, but you have to take into account many nutritional aspects. I really recommend a consult with an experienced dietitian.

    For the protein you might try tofu/tempeh, and combination of grains with small amount of lentils. If you soak the lentils in advance it will help to make them easier digestible. Gas is a normal reaction to huge amount of veggies/beans/lentils… Try to use smaller amount and more of grains, nuts, plant yoghurt.

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