A loose heap of golden-yellow nutritional yeast flakes. ← The FormularyMuscle & performance

Fermented yeast protein

Also known as YESTEIN, nutritional yeast protein
BEVIDENCE

The ingredient that makes a single-plant protein complete.

The honest take
Pairing two plant sources to make one complete protein is old, unglamorous food science. It works, it needs no story, and the story is usually where plant protein goes wrong.
What it is
Protein grown by fermenting yeast, then dried. Not an extract of anything; the yeast is the crop.
How it works
Complementary proteins: two incomplete sources whose gaps do not overlap.
What it does
Fills the amino acid gaps a single plant source leaves. Fava is low in methionine; yeast protein is not.
Who it's for
Anyone eating plant protein who would rather not think about amino acid profiles.
How to use it
Whatever the product it sits inside says.
What to expect
Nothing distinguishable from any other protein.
The research
Judge a plant protein by its full amino acid profile, not its total grams.

Read the labelNutritional yeast is not the same as brewer's yeast, and neither causes candida — a claim we do not make and you should ignore elsewhere.

Evidence grades describe how well an ingredient is studied — A well-supported, C emerging — not a promise of results. Educational, not medical advice. Doses are typical ranges; follow the label on the product.