| Question | Yeast protein | Plant protein |
|---|---|---|
| Biological source | Fungi | Peas, soy, grains or other plants |
| Amino acids | All nine indispensable amino acids possible | Varies; soy is complete, others differ |
| Major allergens | Yeast is not on U.S. major-allergen list | Soy and wheat are major allergens |
| Production | Controlled fermentation | Agriculture plus fractionation |
| Evidence base | Emerging | Varies widely by plant source |
Bottom line
No protein source is universally best. Species, formulation, amino-acid profile, digestibility, allergens, taste and production all matter.