Is Seitan A Complete Protein? [Data]

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Summary:

  • Whether or not seitan is a complete protein depends on the seitan recipe used
  • Most seitan recipes will be low in lysine, because vital wheat gluten is low in lysine
  • Adding ingredients like chickpea flour and nutritional yeast to seitan, which are both common, can potentially make it a complete protein

When you think of complete protein, you think of animal protein sources like eggs, meat, and milk.

As a vegan, you won’t find an argument from me that animal proteins are more convenient and generally higher quality.

But, there are some good sources of plant protein as well.

Tofu is a complete protein for example, and while seitan isn’t quite a complete protein, it’s quite close. 

As long as you’re getting a bit of protein from other sources to balance out your overall amino acid intake, seitan can be a useful source of protein, especially for athletes.

Complete Protein Definition 

There’s no perfect definition of a complete protein, but the general idea is that if you only ate one food (for some reason), you could get all the essential amino acids you need in sufficient quantities.

The best current definition of a complete protein that I could find is this set by the World Health Organization (WHO) (1).

WHO amino acid requirements chart

There are 2 columns:

  • mg/kg per day – Multiply this by your body weight in kilograms to find out how much of each essential amino acid you need per day (the minimum).
  • mg/g of protein – This is essentially the percent of each amino acid in the protein itself (not considering overall amount of protein in the food). You need a certain balance of amino acids to use them most effectively.

The Amino Acid Profile of Seitan

This is tricky, since seitan describes any recipe that mainly uses vital wheat gluten.

There are hundreds of seitan recipes, all with different ingredients.

Some just call for spices, while others also add in ingredients like chickpea flour or nutritional yeast, which will affect the overall amino acid profile.

For now, we’ll just look at the amino acid profile of vital wheat gluten. But I’ll circle back to those other ingredients later.

Below is vital wheat gluten’s amino acid profile in terms of percentages (of protein), which isn’t that easy to find. I had to grab it from a research paper (2).

 Complete Protein (min %)VWG protein (%)
Histidine1.51.7
Isoleucine34.1
Leucine5.97.2
Lysine4.51.4
Methionine+Cysteine1.63.5
Phenylalanine+Tyrosine37.2
Threonine2.32.8
Valine3.95.4

Vital wheat gluten has a relatively high amount of every essential amino acid except for lysine.

The second way we need to look at it is how much of each amino acid can you realistically get from eating seitan.

I looked at the amount in 100 grams of wheat gluten (that’s 75.2 grams of protein) below just because you typically look at nutritional values of food per 100 grams. 

Typically, you’re not going to be eating that much vital wheat gluten in one sitting, but it is possible.

 Needed per day (mg for 65 kg adult)In 100g of Wheat Gluten (mg)
Histidine6501275
Isoleucine13003075
Leucine25355400
Lysine19501050
Methionine+Cysteine9752625
Phenylalanine+Tyrosine16255400
Threonine9752100
Valine16904050

Even half of serving (50g) is enough to get an average person’s RDA in almost all the essential amino acids, which is pretty incredible.

Unfortunately, it still sucks for lysine unless you’re eating an obscene amount.

What About Other Protein Sources In Seitan?

Now’s the time to circle back.

Many recipes include chickpea flour or nutritional yeast.

Well, it just so happens that chickpeas (and other legumes) are some of the best plant sources of lysine. They are low in methionine, but gluten has tons of that, so they’re a good combination.

It’s hard to find an amino acid profile for nutritional yeast, but I eventually tracked one down (3):

In a 15 gram (1/4 cup) serving of nutritional yeast, you’d get 8 grams of protein from nutritional yeast, and 520 mg of lysine. Still not quite a complete protein, but pretty close.

Summary: Seitan Is Typically Not a Complete Protein

It has plenty of most essential amino acids, but seitan is quite low in lysine.

Adding chickpea flour or nutritional yeast to a recipe definitely helps. In some cases it might make the seitan a complete protein, but in most cases it’ll fall a bit short.

That’s not a huge deal, just make sure you’re getting protein sources from other sources than exclusively seitan.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. Chemical engineer turned semi-professional soccer player and freelance nutrition writer. I've been vegan for years and try to make life easier for others by sharing what I've learned.

2 comments

  • Thank you so much for all the research and information. I would appreciate it if you could let us know some of the protein sources we could use in addition to seitan to get the complete protein in our daily meals. For the record, I’m not vegan. I’m vegetarian. Consequently, I probably get all the amino acids I need on a daily basis. My proteins include dairy, nuts, seeds, eggs, grains, and occasional seitan, which I love, btw. It’s just hard to get locally.