Critical Plant Protein Critical Plant Protein is the perfect plant protein blend combining soya protein isolate, pea protein isolate and brown rice protein to deliver a premium quality plant protein powder with a full range of essential amino acids and over 24g of protein per serving. Critical Plant Protein is a good choice for anyone looking to increase their protein intake. Stacked with a high branched chain amino acids profile (BCAAs) leucine, isoleucine and valine, Critical Plant Protein can also help contribute to the growth and maintenance of muscle mass.