Guide
Fava bean protein vs pea protein: what's actually different
Fava bean and pea protein are both plant protein isolates with amino acid profiles the DIAAS scoring system places in the same lower quality tier, below whey. The one direct trial to compare them found pea protein raised blood amino acids more than fava bean at a matched dose, though a separate 12-week trial found pea protein performed no differently than whey overall.
Fava bean protein isolate and pea protein isolate are both plant proteins scored in the same lower amino-acid-quality tier, below whey. The one direct trial to compare them, at a matched dose, found pea protein raised blood amino acids more than fava bean did over the following 3 hours.
| Fava bean protein isolate | Pea protein | |
|---|---|---|
| Source | Vicia faba (fava bean) | Yellow split peas |
| Protein content, isolate form (dry weight) | About 90%, via acid extraction and isoelectric precipitation | Varies by product; not directly measured in the studies below |
| DIAAS quality tier (2020 review) | No quality claim (below 75) | No quality claim (below 75) |
| Blood amino acid response at matched dose (2023 trial) | Lower than pea and whey in the same trial | 28% higher than fava bean over 3 hours |
| 12-week muscle trial (50 g/day) | Not tested in that trial | No significant difference from whey overall |
Fava bean protein isolate: best for, what the evidence shows, watch out for
Best for: anyone choosing it for reasons other than a documented amino-acid-response edge over pea protein — allergy profile, sourcing or a product's other ingredients, for example. What the evidence shows: the one direct human trial found 0.33 g/kg of the isolate, taken right after a leg workout, didn't raise the muscle-building response above a protein-free control; a different, more processed fava bean peptide hydrolysate (not the isolate) has shown positive results at 2.4–20 g/day in separate small trials — see fava bean protein benefits for that distinction. Watch out for: in the one head-to-head trial available, it raised blood amino acids less than pea protein at a matched dose.
Pea protein: best for, what the evidence shows, watch out for
Best for: anyone comparing plant protein sources on the strength of a head-to-head trial, since pea has more direct data against both whey and fava bean than most plant proteins. What the evidence shows: a 2023 trial found pea protein raised blood amino acids significantly more than fava bean protein at the same dose, and a separate 12-week trial found pea protein performed no differently than whey overall on muscle thickness or strength, though it was the only one of the two to differ significantly from a placebo, in a subgroup of the weakest-starting participants. Watch out for: that 50 g/day dose is more than double a typical single protein serving — check whatever product you're considering against its own label rather than that trial's number.
What the head-to-head trial found
A 2023 trial in Nutrients gave 9 healthy young men 0.33 g/kg body mass of whey, pea, or fava bean protein isolate as a single meal-size dose, then tracked blood amino acids for 3 hours. Total indispensable amino acids made up 58% of whey's amino acid composition, 46% of pea's, and 42% of fava bean's. The rise in blood amino acids was 41% greater with whey than pea, 57% greater with whey than fava bean, and pea exceeded fava bean by 28%. It's a small trial — 9 men, one dose, one measurement window — and it measured blood amino acid levels, not muscle growth over time.
What a longer pea-protein trial adds
A separate double-blind, placebo-controlled trial gave 161 men 25 g of pea protein or whey twice daily (50 g/day total) for 12 weeks of upper-body resistance training. Muscle thickness increased over time in all groups, with only a trend toward a difference between pea and whey overall (p=0.09); in a subgroup of participants who started weakest, pea protein's thickness gains were significantly greater than placebo's, while whey's weren't. Strength gains didn't differ significantly between groups. No equivalent multi-week training trial exists for fava bean protein isolate alone — the only direct fava bean data is the single-dose trial above.
Protein quality: DIAAS
A 2020 review calculated Digestible Indispensable Amino Acid Scores (DIAAS) for 17 animal- and plant-based proteins using published amino acid and digestibility data. Whey and soy were classified "high quality" (DIAAS at or above 75); pea and fava bean, along with oat, rice, hemp, corn, canola, rapeseed, lupin and gelatin, fell into the review's "no quality claim" category (below 75). Neither pea nor fava bean protein has a documented amino-acid-quality edge over the other by this measure.
Questions people ask
Is pea protein better than fava bean protein?
In the one head-to-head trial available, pea protein raised blood amino acids more than fava bean protein at a matched dose. Both scored in the same lower DIAAS quality tier, so the gap between them is smaller than either has with whey.
Which is better for building muscle?
The head-to-head trial measures a blood amino acid response over hours, not muscle gained over weeks. Pea protein has a separate 12-week muscle trial showing results similar to whey overall; there's no equivalent training study for fava bean protein isolate alone.
Can I use fava bean and pea protein together?
No trial we found tested the two combined. A 2020 DIAAS review found that mixing complementary plant proteins generally raised the pooled amino-acid score, which is a reasonable basis for pairing them, though it wasn't tested for this specific pair.
Related reading: fava bean protein vs whey and fava bean protein benefits.
Sources
- An Investigation of the Protein Quality and Temporal Pattern of Peripheral Blood Aminoacidemia following Ingestion of 0.33 g·kg(-1) Body Mass Protein Isolates of Whey, Pea, and Fava Bean in Healthy, Young Adult Men In 9 healthy men given the same 0.33 g/kg dose of each, whey protein isolate raised blood amino acids significantly more over the next three hours than fava bean protein isolate did, reflecting whey's higher indispensable amino acid content.
- Comprehensive overview of the quality of plant- And animal-sourced proteins based on the digestible indispensable amino acid score A 2020 review classified whey as a "high quality" protein by DIAAS score, while fava bean protein fell below the quality-claim threshold used in the same review, in the same tier as pea, oat and rice protein.
- The Effect of Fava Bean (Vicia faba L.) Protein Ingestion on Myofibrillar Protein Synthesis at Rest and after Resistance Exercise in Healthy, Young Men and Women: A Randomised Control Trial In 16 healthy adults, drinking 0.33 g/kg of fava bean protein isolate right after a leg workout did not raise the muscle-building response above a protein-free control.
- Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein In a 12-week trial in 161 men, pea protein and whey protein (each dosed at 50 g/day, more than double our serving) produced no significant difference between them on muscle thickness or strength gains; only pea protein differed significantly from placebo, and only in a subgroup of the weakest starting participants.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.