Supplement · Protein & amino acids
Soy protein isolate
A complete plant protein that supports muscle much like whey.
- Evidence
- Gold· human data
- Sources cited
- 1
- Last reviewed
- 22 July 2026
Soy protein isolate is a complete plant protein containing all the essential amino acids in useful amounts, which sets it apart from most single plant proteins. It is a long-standing vegan option for reaching protein targets.
The muscle evidence is solid: when total protein and leucine are adequate, soy supports training much like whey, if marginally less potently per gram. Concerns that normal soy intakes disrupt testosterone or oestrogen are not borne out in controlled human studies.