Plant-based proteins: differences, best sources and how to reach RDA

Before talking about plant-based proteins, a few words about proteins and amino acids in general.
Every cell of our organism is composed by proteins: not only muscles, bones, skin, hair and blood, but also that invisible and miraculous part of every living being, such as hormones and enzymes.
All proteins are made up of amino acids, which owe their name to their composition; in fact they contain an amino group (-NH2) and an acid group (carboxyl group -COOH) and thanks to the peptide bond that acts as a glue, they make up proteins together.
Although the amino acids present in nature are several hundreds, those that concern our diet are only about twenty; 9 of these [1] are called essential: because the body is not able to synthesize them and therefore we must introduce them through food.

Differences between plant and animal proteins

Protein foods can be of either animal or plant origin. Their origin results in different bioavailabilities.
The term bioavailability refers to the evaluation of amino acids under three key points, able to influence the percentage of amino acid obtainable by the body from a specific food: digestibility, chemical integrity and the presence of substances interfering with the absorption.

– animal proteins contain all essential amino acids, therefore defined as complete; they have a high bioavailability (>95%: the body does not have to perform complex conversions to reach the desired amino acids) and therefore a high biological value; a fact that gives them the adjective “noble” (or sometimes “simple”).

– plant-based proteins have a lower biological value, i.e. relatively low bioavailability (between 50-90%): the body is not able to assimilate all the proteins present.
This is due to the presence of inhibitors of digestive enzymes and antagonists of digestion, defined as antinutrients.
Last but not least, plant-based proteins do not offer a complete profile of essential amino acids: except for soy, amaranth and quinoa.
Generally we can say that plant-based proteins have lower levels of leucine, methionine, lysine and tryptophan: in particular cereals are poor in lysine and legumes in methionine.

What has been said up to now could frighten those who are thinking about reducing or eliminating meat consumption for reasons concerning health or ethical-environmental issues: cancel any fear, there is nothing to be afraid of!
Although the world of plants does not offer the same bioavailability of animal proteins, the difference can be easily bridged with a few extra grams of protein and a varied diet.
 

How much protein should an adult consume?

Proteins are used in the production of vital substances such as hemoglobin, enzymes, and hormones. That’s why protein intake is essential for the growth and repair of body cells; the transmission of nerve impulses; the body’s defense through immune responses; and the normal functioning of muscles, since protein is the main structural component of muscle tissue, just as it is for other tissues in the body.
By ensuring that the body is getting the right amount of protein, we are basically continuing to be alive and healthy [2].
 

Protein requirements

There are guidelines to determine the needs of nutrients for populations: in Italy there are the LARN (Levels of reference intake of nutrients and energy for the Italian population).
According to which:

– Italian adults, male and female, between 18 and 60 years old, and non-athletes should introduce minimum 0.71 g of protein per body weight per day (The average requirement is 0.71 while the recommended intake for the population is 0.90 g of protein per body weight). But universally, 0.83 g of protein per body weight is recommended.
This means that my husband (Italian), who can be defined as an omnivore, with his 72 kilos should take minimum 51 grams of protein per day; using the universal proportion instead he should introduce 60 grams of protein.

– for pregnant and lactating women, an additional 0.5 to 21 grams of protein should be considered;

– for people over 60 years old it is advisable to use an increased coefficient: 1.1 g of protein/body weight;
 

And for my vegan friend?

I would feel more comfortable suggesting to him the international recommendations for vegans on protein intake: 0.9 g protein/body weight while for vegetarians who still eat eggs, milk and derivatives the international ratio for omnivores which is 0.83 g protein/body weight is more than perfect [2]. Which means, about 63 grams of protein for my vegan friend of 70 kilos, for my lacto-ovo vegetarian friend consider only 58 grams of protein with the same weight.

…Eating without compromising on taste: 

for breakfast

– 100 ml soy drink (3.3g) or 100 ml oat drink (1.5g) or 100 g of soy yogurt (3.5g)
– 30g tahini with grape molasses (4g) or 30g almond cream (10g) 

for lunch

– sautèed Brussels sprouts (5g) or a purslane salad (5g)
– barley salad with seasonal vegetables (about 16g) or a plate of fusilli with broccoli and pea puree (about 25g), or an easily veganizable risotto like this one (5g) 

for dinner

– a sliced tomato with 100g of guacamole (4g), or a side dish of rice, leeks and carrots (4g)
– a generous lentil soup (10g) or a vegetable curry soup (6g)
– vegan kokorec (16g) or a plant-based burger (22g) 

bread

– 60g of spelt sourdough bread (7g), to be divided at meals

So there you have it all, without even mentioning snacks and/or fruit.

Especially for those who live in Western countries and lead a varied and balanced diet such as the one just described, the absorption of plant-based proteins does not differ much from animal proteins: as we have seen, obtaining 60 grams of protein is more than easy, even without the aid of isolated plant-based protein powders.
Different for those who live in less fortunate areas of the world and consequently follow diets based on repetitive and limited foods (for example based on corn, sorghum, rice etc).
In this case it would not be wrong to compensate for the poor quality of plant-based proteins by increasing the quantity of food: 1 gram of protein per body weight could be sufficient.

Although vegetable proteins are incomplete, it does not mean that essential amino acids do not exist at all: there is always a minimum of all amino acids.
And here I would like to dispel another myth: it is not mandatory to take all essential amino acids in the same meal; the important thing is to take them all throughout the day [3].
 

What we risk if we exceed protein requirements

As it is easy to deduce from these considerations, in the Western part of the world we very often exceed by far the recommendations regarding protein requirements, with consequent damage to the environment, to the animals involved and to the human body.
Especially when it comes to animal proteins, abundance is never synonymous with well-being: their digestion requires a greater effort for kidneys, pancreas, liver, stomach and intestine, due to the management of “processing residues”.
Damage to digestive organs is not limited to wear and tear: IARC – The International Agency for Research on Cancer – has defined red meat as a possible carcinogen (Group 2A); and put the processed red meats (like sausages) in the same category (Group 1) of carcinogens, in the company of smoking and asbestos (although of course not at the same level of danger)[4].
In order not to ask our vital organs for continuous efforts, we should move towards a balanced diet based on a limited intake of proteins of animal origin, giving priority to plant-based proteins.

As provided for in the CHEtarian diet, thanks to which it is possible to conduct a truly healthy and balanced diet, without eliminating meat altogether, but reducing the amount in a significant way.

DISCOVER HERE WHY REDUCING MEAT CONSUMPTION IS A HEALTHY ACT AND AT THE SAME TIME AN ENVIRONMENTALIST CHOICE

Plant-based proteins

Only few foods do not contain protein; apples and celery, are among the rare plant foods with negligible levels of protein.
But in general it must be said that the enormous advantage of plant-based proteins lies in their potential unlimited intake (except for some varieties such as oil seeds and nuts); a fact that, as mentioned earlier, guarantees the easy achievement of requirements without any worries.
Broccoli, for example, contains just 3 grams of protein per 100g, but eating a half a pound of it, together with some pine nuts and sun-dried tomatoes, is very simple and tasty: think of it as a side dish, a snack, or as a condiment for a pasta dish; if you want, every day, without any sense of guilt or danger to your health, or harm to other living beings.
 

The types of plant-based proteins

We can roughly group proteins of vegetable origin in:

– seeds (chia, hemp, pumpkin, sesame, sunflower, flax, etc.);
– dried fruits (pine nuts, walnuts, almonds, hazelnuts, pistachios etc);
– legumes (soybeans, beans, peas, lentils, broad beans, lupins etc);
– cereals (such as wheat, spelt, barley, rye, oats etc);
– pseudo-cereals (quinoa, buckwheat, amaranth etc);
– fruits (avocado, peach nuts, kiwi, bananas etc);
– vegetables (broccoli, asparagus, spinach, zucchini, Brussels sprouts, etc.);
– soy and wheat derivatives (tempeh, miso, tofu and seitan);
– algae (such as spirulina, wakame etc.) I want to include them among the vegetables, although they also have “animal characteristics”;
– mycoproteins (a protein produced from fungus, like Quorn);
 

25 most popular plant-based protein foods used in vegetarian and vegan diets

Table based on data obtained from the work of FAO and WHO [5]

From now on you have all the information you need to fill your shopping cart in the best way possible.
Have a lovely day and good revolution to all

Bibliography
1) Review – Maximizing the intersection of human health and the health of the environment with regard to the amount and type of protein produced and consumed in the United States. Gardner CD, Hartle JC, Garrett RD, Offringa LC, Wasserman AS Nutr Rev. 2019 Apr 1; 77(4):197-215.
2)Joint WHO/FAO/UNU Expert Consultation. Protein and amino acid requirements in human nutrition. World Health Organ Tech Rep Ser 2007; 935
3) Young V.R., Pellett P.L. Plant proteins in relation to human protein and amino acid nutrition. Am. J. Clin. Nutr. 1994;59:1203S–1212S. doi: 10.1093/ajcn/59.5.1203S.
4) International Agency for Research on Cancer. Volume 114: Consumption of red meat and processed meat. IARC Working Group. Lyon; 6–13 September, 2015. IARC Monogr Eval Carcinog Risks Hum (in press).
5) Food and Agriculture Organization/World Health Organization United Nations University. Energy and protein requirements. Report of joint FAO/WHO/UNU expert consultation. Geneva: World Health Organization. 1985.

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