Soy Protein
Soy protein is a complete plant protein extracted from soybeans. It contains every essential amino acid, has a long research history, and matches whey in most muscle-building studies. Soy isolate is the most refined form and is used in many ready-to-drink shakes.
Why It Matters
Soy is the rare plant protein that does not need to be blended with anything else to be complete. Despite decades of internet noise about phytoestrogens, large reviews of clinical data find no measurable feminizing effect at typical supplement doses (20 to 40g per day) in either men or women.
How to Spot It on a Label
Look for soy protein isolate (SPI) on the label, ideally as the sole protein source. Soy protein concentrate is a lower-grade form often used in bars. Some products call out 'non-GMO soy' for buyers who prefer that.
Examples from real products
Related Terms
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