Is pea protein complete?

Whether you’re a nutritionally-concerned vegan, a frequent exerciser looking to supplement protein, or just interested in dietary choices, you may have asked yourself, “is pea protein complete”? Is it nutritionally sufficient to use as my main protein source? Unfortunately, the internet is full of poorly referenced blog articles indirectly citing one another. This post is different! We’re going to break pea protein down into its constituent parts, and answer the question properly. We’ve examined scientific papers ourselves and have got the graphs to prove it. 

What do we mean by ‘a complete protein’?

Protein is a macro-nutrient, meaning it’s one of the major types of nutrients we need in our diet. Proteins themselves are made up from ‘amino acids’. To function correctly the human body needs 21 amino acids. The body can make the majority of these itself. But 9 of 21 amino acids cannot be produced in the body, so need to be obtained from food. A ‘complete protein’ is a protein that contains the 9 essential amino acids (EAAs).

What quantity of amino acids do we need from protein?

A generally accepted dietary recommendation is for the average person to eat around 0.7g of protein per kg of body weight. A bit more if you’re exercising regularly and perhaps looking to bulk up. In addition to eating the correct amount of protein, this protein should also contain the correct amounts of amino acids needed by the human body. This is so you don’t become nutritionally deficient, and then need to supplement and eat a higher quantity of protein than is considered part of a ‘normal’ diet. 

The reputable World Health Organisation released a review paper in 2007 entitled ‘Protein and amino acid requirements in human nutrition’. This paper reviews and recommends amino acid intake for humans. So we can see in the table below that there are guidelines for EAA intake based on 100g of protein, and per kg of body mass. There are called amino acid profiles. 

EAA type WHO guide EAA content g/100g WHO guide, EAA intake, g/kg body mass
Histidine 1.5 0.01
Isoleucine 3.0 0.02
Leucine 5.9 0.04
Lysine 4.5 0.03
Methionine 3.8 0.01
Phenylalanine 3.8 0.03
Threonine 2.3 0.02
Tryptophan 0.6 0.00
Valine 3.9 0.03

But how do these WHO requirements compare to the amino acid profile of pea protein? 

What quantity of amino acids does pea protein provide?

Information on the internet can be unreliable. So I dug in and found different numbers from different sources regarding the amount of amino acids contained in pea protein. I have considered 8 sources, including 2 scientific papers (here and here), and 6 manufacturer claims from packaging of pea protein powders. I took an average of these values, as seen in the below table.

EAA type EAA content, average pea protein, g/100g
Histidine 1.5
Isoleucine 3.2
Leucine 6.4
Lysine 5.2
Methionine 1.0
Phenylalanine 4.0
Threonine 3.0
Tryptophan 1.1
Valine 3.9

 

So is pea protein complete?

The quick answer is yes – pea protein is complete. It contains all 9 of the essential amino acids required by our bodies. But it’s a bit low on 1 amino acid in particular – methionine.

We compare the numbers in the graph below. For methionine, the red column (pea protein amount) is much lower than the blue column (WHO guide value).

This means that if pea protein was the only source of protein in your diet, you may be deficient in methionine, dependent on your body size and protein intake. 

is pea protein complete, amino acid graph 600w

 

What quantity of amino acids do we need to intake?

As discussed above, the WHO paper gives guidelines on the amount of amino acids we require (complete protein). These are outlined in the table above, with values based on the food type, ‘WHO guide EAA content g/100g’ and based on body mass ‘WHO guide, EAA intake, g/kg body mass’. You can approximate the amount of amino acids you require, based on your mass. 

If we assume an 80kg person, they’ll need an amount of amino acids as shown in the following graph (in blue).

I’ve also added how much 1 scoop of average pea protein provides (in red).

is pea protein complete, amino acid graph 2 600w

You should be able to see that 1 typical scoop (30g) of pea protein powder is not sufficient for most EAAs, for an 80kg person. However, to avoid being deficient, you can simply adjust (increase in this case) the quantity of pea protein you eat. Go to 2 scoops! ‘Protein content and amino acid composition of commercially available plant-based protein isolates’ makes this point clearly.

If our 80kg person wanted to meet the WHO guide amounts for amino acid intake, from eating pea protein only, they’d need to eat an amount of pea protein as shown on the following graph:

is pea protein complete, amino acid graph 3 600w

You should be able to see that an 80kg person can get most of their EAA needs from 2 scoops of pea protein powder (excluding methionine). 

However, if I obtained all my amino acids from pea protein, i’d need to eat around 77g of protein, which puts me over the daily recommended amount of protein.

Recalling that we should have around 0.7g of protein per kg of body weight, an 80kg person should eat around 60g of protein per day. So we’re 17g over our recommended dietary intake.

This isn’t really a big difference, and probably doesn’t matter. But… another option would be to obtain the deficient amino acid from another source that is richer in the missing amino acid. I could eat a mix of different protein sources to stay within my protein limit, and gain the spectrum of amino acids needed. Add in some brown rice, various beans, maybe a pasture raised egg depending on your lifestyle choice.

More info and further reading

If you would like to read more about pea protein, check out our page on pea protein smoothies. What’s not to love about an easy, nutritionally-effective, and time-efficient snack?

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