Types of plant protein compared

Plant protein isn't one thing. Soy, pea, rice, hemp and fava bean are the sources most often sold, and they don't score the same on protein quality: a 2020 comparative analysis classifies soy as "high quality" by the standard amino-acid-scoring method, while pea, rice, oat, hemp and fava bean — the source in our own blend — fall below the threshold used for that claim.

The sources most often sold as "plant protein"

Soy, pea and rice are the three most common single sources in commercial powders. Hemp and fava bean show up more often in blends. Each comes with its own trade-offs beyond taste: soy is a common allergen and carries naturally occurring isoflavones (plant compounds structurally similar to estrogen, covered in plant protein vs soy); pea and rice are frequently paired together specifically because their amino acid profiles fill in each other's gaps; fava bean is less common as a stand-alone ingredient and shows up mostly in newer blends, including ours.

Protein quality differs by source, measured by DIAAS

The Digestible Indispensable Amino Acid Score (DIAAS) grades a protein by how much of each essential amino acid it supplies and how digestible it is, then compares that against a reference pattern. A 2020 analysis calculated DIAAS for 12 plant-based and 5 animal-based proteins. Casein, egg and potato protein scored above 100 ("excellent quality"). Whey and soy scored 75 or above ("high quality"). Gelatin, rapeseed, lupin, canola, corn, hemp, fava bean, oat, pea and rice all scored below 75 — a category the analysis describes as not meeting the bar for a quality claim. Soy is the one plant source in this dataset that reaches the same tier as whey.

Source	DIAAS tier (2020 analysis)	Common allergen	In our Plant Protein
Soy	High quality (≥75)	Yes — top 9 FDA allergen	No
Pea	No quality claim (<75)	Uncommon but reported	No
Rice	No quality claim (<75)	Rare	No
Hemp	No quality claim (<75)	Rare	No
Fava bean	No quality claim (<75)	Rare	Yes — fava bean protein isolate
Fermented yeast protein	Not tested in this analysis	Uncommon	Yes — YESTEIN™

The same analysis found that combining complementary plant proteins can raise the pooled DIAAS above what either source manages alone — one reason multi-source blends exist. It didn't test a fermented yeast protein, so we can't say where our specific pairing of fava bean isolate and YESTEIN™ lands on this scale; that's a genuine gap, not a number we're rounding up.

What a dose-close trial found for fava bean protein specifically

Quality scores like DIAAS are lab measurements, not the same as a trial in people. The closest human trial we found tested fava bean protein at 0.33 g per kg of body weight — about 23 g for a 70 kg adult, close to the 21 g in our own two-scoop serving — against an amino-acid-free control, in 16 healthy young adults after a bout of resistance exercise. Fava bean protein did not produce a statistically significant increase in muscle protein synthesis over the control, at rest or after exercise. That's one small trial, and it tested fava bean protein generally rather than confirming an identical isolate to ours, but it's the closest dose-matched human data available for the plant source in our blend, and it doesn't support a muscle-building claim at this dose.

Soy is the exception with the most direct evidence

A 2018 meta-analysis of 9 randomized trials (266 adults doing resistance training for at least 6 weeks) found soy protein produced strength and lean-mass gains statistically similar to whey, beef or milk protein. That's the most direct head-to-head result for any plant protein against animal protein. It's a result for soy specifically — it doesn't transfer to pea, rice, hemp or fava bean, which have different amino acid profiles and weren't tested in that comparison.

Where our label sits

Electric Tiger Plant Protein (Chocolate) blends fava bean protein isolate with YESTEIN™ fermented nutritional yeast protein: 21 g of protein per two-scoop serving (34.7 g), 110 calories, 1 g of sugar, 24 servings a tub, as low as $54.47 on subscription (about $2.27 a serving). Every ingredient is printed on the panel; there's no proprietary blend hiding the ratio. The label doesn't print an amino acid breakdown, so we don't call it "complete protein" — see the label.

Questions people ask

Which type of plant protein is highest quality?

By DIAAS scoring specifically, soy is the only plant source in the "high quality" tier in the 2020 analysis above; pea, rice, hemp, fava bean and oat all scored below that threshold. "Highest quality" by this one lab measure doesn't automatically mean "best for your goals" — soy is also the plant protein with the most direct muscle-building trial evidence.

Is pea protein a complete protein?

Not by the DIAAS standard used in the analysis above — it scored below the 75 threshold used for a "high quality" claim, in the same tier as rice, oat, hemp and fava bean.

Is fava bean protein a complete protein?

No, by the same measure. It's classified below the quality-claim threshold, and the closest dose-matched human trial found it didn't raise muscle protein synthesis over a no-protein control at a dose close to what our label provides.

What's the difference between pea protein and rice protein?

Both scored in the same "no quality claim" DIAAS tier in the analysis above. They're commonly paired together in other brands' blends because their individual amino acid gaps differ, so combining them can raise the pooled score — the same logic behind any multi-source blend, including ours.

Does blending plant proteins make them better?

The 2020 analysis found that mixing complementary plant proteins in the right ratio can raise the pooled DIAAS above any single source. That's a measurement of amino acid and digestibility scoring, not a muscle-building trial of a specific blend — including ours, which wasn't tested in that analysis.

Related reading: what is plant protein? a plain guide, plant protein vs soy, and plant protein vs isolate: what "isolate" actually means.