The Influence Of Oral Tyrosine And Tryptophan Feeding On Plasma Catecholamines In Man
Notes for this study:
||pg/ml. Placebo: 4.2 ± 0.16 Tyrosine: 4.4 ± 0.28
||Non-randomized controlled trial
|Number of Subjects
In a double-blind, placebo-controlled crossover trial with unclear randomization, 12 healthy male participants took 7.5 g of tyrosine or placebo, or 3 g of tryptophan or placebo daily for 7 days before crossing over (that is, subjects didn't take both tyrosine and tryptophan, only either and placebo).
Plasma free and conjugated norepinephrine declined statistically significantly when taking tyrosine. Free epinephrine was lower and conjugated epinephrine was higher, but the difference wasn't statistically significant. Dopamine was lower, L-dihydroxyphenylalanine was higher, and renin wasn't different, none of which were statistically significant. There weren't statistically significant differences for urinary hormones, blood pressure, or heart rate.