OBJECTIVE: To test the efficacy of tyrosine supplementation, as an adjunct to dietary treatment, on neuropsychological test performance in individuals with phenylketonuria. DESIGN: A randomised controlled trial of tyrosine supplementation using a double blind crossover procedure with three four week phases. SETTING: The Hospital for Sick Children, Toronto. PARTICIPANTS: 21 individuals with phenylketonuria (ages 6 to 28 years, mean 11.3). INTERVENTION: Participants were given 100 mg/kg body weight/d of L-tyrosine or L-alanine (placebo). RESULTS: At baseline, performance on several of the neuropsychological test measures was correlated with tyrosine levels. Dietary supplements of tyrosine increased plasma tyrosine concentrations; however, no change in test performance was found across the tyrosine and placebo phases of the study. CONCLUSIONS:Tyrosine supplementation of this type does not appear to alter neuropsychological performance in individuals with phenylketonuria.
RCT Entities:
OBJECTIVE: To test the efficacy of tyrosine supplementation, as an adjunct to dietary treatment, on neuropsychological test performance in individuals with phenylketonuria. DESIGN: A randomised controlled trial of tyrosine supplementation using a double blind crossover procedure with three four week phases. SETTING: The Hospital for Sick Children, Toronto. PARTICIPANTS: 21 individuals with phenylketonuria (ages 6 to 28 years, mean 11.3). INTERVENTION: Participants were given 100 mg/kg body weight/d of L-tyrosine or L-alanine (placebo). RESULTS: At baseline, performance on several of the neuropsychological test measures was correlated with tyrosine levels. Dietary supplements of tyrosine increased plasma tyrosine concentrations; however, no change in test performance was found across the tyrosine and placebo phases of the study. CONCLUSIONS:Tyrosine supplementation of this type does not appear to alter neuropsychological performance in individuals with phenylketonuria.
Authors: A M J van Wegberg; A MacDonald; K Ahring; A Bélanger-Quintana; N Blau; A M Bosch; A Burlina; J Campistol; F Feillet; M Giżewska; S C Huijbregts; S Kearney; V Leuzzi; F Maillot; A C Muntau; M van Rijn; F Trefz; J H Walter; F J van Spronsen Journal: Orphanet J Rare Dis Date: 2017-10-12 Impact factor: 4.123
Authors: Bill Campbell; Colin Wilborn; Lem Taylor; Mike Greenwood; Stephen Schmitz; Rick Collins; Jose Antonio; Paul La Bounty; Mike T Nelson; Tim N Ziegenfuss; Hector L Lopez; Jay R Hoffman; Jeffrey R Stout; Doug S Kalman; Richard B Kreider Journal: J Int Soc Sports Nutr Date: 2013-01-03 Impact factor: 5.150