“Pea protein supplementation, in addition to appropriate training, promoted greater gains in muscle thickness compared to placebo, especially in those who started or resumed muscle building. As there was no difference between the two protein (pea protein, whey protein) groups, Plant-based pea protein can be used as an alternative to whey-based dietary products."
Reference paper: Babault, N., Païzis, C., Deley, G., Guérin-Deremaux, L., Saniez, M.-H., Lefranc-Millot, C., & Allaert, FA (2015). Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, placebo-controlled clinical trial vs. Whey protein. Journal of the International Society of Sports Nutrition, 12(1), 3.