Piperine improved the safety of swallow by : ( a ) reducing the prevalence of unsafe swallows by -34.48 % ( P = 0.004 ) at 150 M and -57.19 % ( P < 0.001 ) at 1 mM , and the severity score of the penetration-aspiration scale from 3.25 0.51 to 1.85 0.27 ( P = 0.003 , 1 mM ) ; and ( b ) shortening the time to laryngeal vestibule closure from 0.366 0.024 to 0.270 0.022 s with 150 M piperine ( P < 0.001 ) and from 0.380 0.032 to 0.306 0.028 s with 1 mM piperine ( P < 0.05 ) .