peer reviewed protein

The science

peer reviewed protein

Wondering if yeast protein actually works? Fair question. It's new to most people. Researchers have spent the last few years measuring it against the leading proteins. Everything they published is below, summarized plainly and linked in full.

Matched whey,
head to head.

Does yeast protein build muscle like whey? Researchers ran the gold-standard test to find out: randomized, double-blind, placebo-controlled, nobody knew who was drinking what. Eight weeks later, the yeast group had gained as much lean muscle and strength as the whey group. And the men who weren't eating enough protein? They gained the most of anyone, while the placebo group lost muscle.

  • Human · Randomized
  • Double-blind
  • Placebo-controlled
  • n=79 · men 40+
  • 8 weeks · 40g/day

Lean mass gained · all participants

+828g

about 1.8 lb of lean muscle · yeast · 8 weeks

  • Placebo
  • Whey
  • Yeast protein
0g
300
600
900
+448g Placebo
+741g* Whey
+828g* Yeast Protein
Lean mass gained · all participants
Group grams of lean mass gained
Placebo +448g
Whey +741g*
Yeast Protein +828g*

Lean mass gained · men eating too little protein

+867g

about 1.9 lb · yeast — while placebo lost muscle

  • Placebo
  • Whey
  • Yeast protein
0g
300
600
900
-99g Placebo
+440g* Whey
+867g* Yeast Protein
Lean mass gained · men eating too little protein
Group grams of lean mass gained
Placebo -99g
Whey +440g*
Yeast Protein +867g*

*Statistically significant (p < 0.05). Left panel: significant vs own baseline; the yeast-vs-placebo difference across all participants was not statistically significant. Right panel: men eating under 1.2g protein/kg/day (48 of 79 participants) — here the yeast group's gain was significant vs placebo. Total-body lean mass by DEXA. All groups performed the same resistance-training program.

Briskey et al., 2024. Journal of Food and Nutrition Research, 12(5), 292–300.

Six months later,
still moving forward.

Protein matters more as you get older, but does yeast protein hold up in real life? In a 6-month trial, adults in their 70s took 20g a day. They walked faster and scored higher on physical-performance tests, while the group that took nothing declined. Only the yeast group improved enough for researchers to call it clinically meaningful.

  • Human · Randomized
  • n=92 · avg age 73
  • 24 weeks · 20g/day
  • Control: no supplement

Physical performance · SPPB score change

+0.9

yeast — the clinically meaningful threshold · p=0.002

  • No supplement
  • Whey
  • Yeast protein
-1 0 +1
Yeast protein +0.9
Whey +0.3
No supplement -1.7
Physical performance · SPPB score change
Group SPPB points, change from baseline
Yeast protein +0.9
Whey +0.3
No supplement -1.7

Walking speed change · m/s

+0.2

m/s yeast · both proteins beat control · p=0.003

  • No supplement
  • Whey
  • Yeast protein
-0.1 0 +0.1 +0.2
Yeast protein +0.2
Whey +0.1
No supplement -0.1
Walking speed change · m/s
Group metres per second, change from baseline
Yeast protein +0.2
Whey +0.1
No supplement -0.1

SPPB = Short Physical Performance Battery, a standard 12-point test of balance, walking, and standing up from a chair. Between-group differences significant for SPPB (p=0.002) and walking speed (p=0.003); researchers generally consider a +0.1 m/s change in walking speed meaningful — the yeast group doubled that. Muscle mass and grip strength did not differ significantly between groups — the measured benefit was function. The control group received no supplement (not a placebo).

Bai et al., 2026. Food Science & Nutrition, 14(3), e71552.

Whey-level essentials.
No animal required.

Your body can't make nine of the amino acids it needs, they have to come from food. So researchers measured six proteins side by side: how much of the essential stuff does each one actually deliver? Yeast protein landed right next to whey, and far ahead of every plant protein tested.

  • Animal + lab digestion model
  • Six proteins compared
  • Indispensable amino acids · mg per g protein
Whey isolate 528 Whey concentrate 511 Yeast protein 508 Soy 398 Pea 384 Wheat 303
0mg indispensable amino acids / g protein
Group mg indispensable amino acids / g protein
Whey isolate 528
Whey concentrate 511
Yeast protein 508
Soy 398
Pea 384
Wheat 303

Same study · leucine — the amino acid that flips the muscle-building switch

98.6

mg per g protein — nine-tenths of whey, 22–44% more than any plant

Whey isolate 116.7 Whey concentrate 110.7 Yeast protein 98.6 Soy 80.5 Pea 77.3 Wheat 68.6
0mg leucine / g protein
Same study · leucine — the amino acid that flips the muscle-building switch
Group mg leucine / g protein
Whey isolate 116.7
Whey concentrate 110.7
Yeast protein 98.6
Soy 80.5
Pea 77.3
Wheat 68.6

Same study · in-vivo PDCAAS (protein quality, 1.00 is the ceiling)

Yeast protein 1.00 Whey 1.00 Soy 0.98 Pea 0.89
0
Same study · in-vivo PDCAAS (protein quality, 1.00 is the ceiling)
Group
Yeast protein 1.00
Whey 1.00
Soy 0.98
Pea 0.89

Indispensable (essential) amino acid content per gram of protein, measured across six commercial protein isolates/concentrates. Yeast protein also recorded the highest indispensable-to-dispensable amino acid ratio (0.91) of the six, the highest valine content of all six proteins, and total BCAAs on par with whey concentrate (236 vs 239 mg/g, calculated from the paper's amino-acid table). PDCAAS measured in growing rats; values in people may differ. 1.00 is the maximum score.

Cao et al., 2025. Food Chemistry, 463, 141178.

Absorbed like whey.

The oldest knock on a non-dairy protein: "sure, but does your body actually use it?" Researchers ran yeast protein through a five-hour simulation of the human gut, the same kind of model used to study medicines, and measured how much protein was ready to absorb. The answer: the same amount as whey, down to a tenth of a percent.

  • Human GI simulation (TIM-1)
  • Ex-vivo fermentation · 11 human donors
  • Protein ready to absorb after 5 hours
Yeast protein 48.6%
Whey 48.7%
vs

One-tenth of a percent apart. Statistically, that's a tie. (And no — the other half isn't wasted. Digestion keeps going past the five-hour mark; what the test shows is that both proteins move at the same pace.)

Group % of protein bio-accessible after 5 hours
Yeast protein 48.6%
Whey 48.7%

Cumulative bio-accessible protein after 5 hours of simulated gastric + small-intestine digestion (TIM-1 model). The two values were statistically comparable.

Caron et al., 2025. Food Research International, 208, 116098.

Less gas than
whey or soy.

The reason many people quit whey isn't the taste, it's how it makes them feel. Researchers fed all three proteins to real human gut microbes in a lab model (no stomachs were harmed) and measured the gas produced as each one fermented. Yeast protein made the least: 27% less than whey, 19% less than soy.

  • Lab model · human gut microbes
  • 6 donors · ages 50–65
  • Dose modeled: 40g/day

Gas produced during fermentation · indexed, whey = 100

27%

vs whey · −19% vs soy — and the strongest gut-barrier support of the three

Whey 100 Soy 90 Yeast protein 73
0 · lower is better
Gas produced during fermentation · indexed, whey = 100
Group vs whey · −19% vs soy — and the strongest gut-barrier support of the three
Whey 100
Soy 90
Yeast protein 73

Gas normalized per unit of beneficial short-chain fatty acids produced; index calculated from the paper's reported differences (−27% vs whey, −19% vs soy; whey set to 100). Ex-vivo model using gut microbiomes from six men aged 50–65 — not a human feeding trial. The same study found yeast protein gave the gut lining's barrier the strongest reinforcement of the three proteins.

Van den Abbeele et al., 2026. Frontiers in Microbiology, 16:1697734.

The research behind yeast protein.

Every study, strongest evidence first: what kind of study it was and what it found. No cherry-picking.

Spacemilk guides

Yeast protein, explained

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