Probiotic - enhanced pea protein improves skeletal muscle hypertrophy: comparative study with whey in rats

Plant - based proteins are gaining attention as sustainable alternatives to animal - derived sources; however, their limited digestibility and suboptimal amino - acid profile often reduce their anabolic potential. Bacillus coagulans GBI - 30, a spore - forming probi otic, has demonstrated an ability to enhance protein digestion and amino - acid absorption in both in vitro and in vivo studies. The present investigation compared the effects of whey protein, pea protein isolate, and probiotic - supplemented pea protein on sk eletal - muscle hypertrophy in rats. Adult male Wistar rats (n = 32) were randomly divided into four groups: (A) control — standard diet, (B) whey protein supplement, (C) pea protein isolate, and (D) pea protein + B. coagulans GBI - 30 (1 × 10⁹ CFU/day). All gro ups received iso - nitrogenous diets for eight weeks with mild resistance training (ladder - climbing model). Body weight, muscle wet weight (gastrocnemius, soleus), muscle - fiber cross - sectional area, and serum amino - acid concentrations were measured. Molecula r markers of muscle anabolism (p - mTOR, p - S6K) were analyzed by Western blot. Whey and pea protein both significantly increased lean mass and muscle - fiber size compared with the control (p < 0.05). Pea + probiotic supplementation produced the greatest incre ases in muscle wet weight, serum essential amino acids, and activation of mTOR signaling versus pea protein alone (p < 0.01). No adverse effects were observed. Co - administration of B. coagulans GBI - 30 enhances the anabolic efficacy of pea protein, yielding muscle - growth outcomes comparable to or exceeding whey supplementation. Probiotic - fortified plant proteins may thus represent an efficient, sustainable strategy for promoting skeletal - muscle hypertrophy .