Tyrosine supplementation for phenylketonuria.
Tracey Remmington1, Sherie Smith2
1Department of Women's and Children's Health, University of Liverpool, Liverpool, UK.
The Cochrane Database of Systematic Reviews
|January 11, 2021
Summary
Tyrosine supplementation in phenylketonuria (PKU) significantly increased blood tyrosine levels but did not improve other outcomes. More research is needed, but this is not an active area of study.
Area of Science:
- Metabolic Disorders
- Genetics
- Nutritional Science
Background:
- Phenylketonuria (PKU) is an inherited disorder requiring strict phenylalanine restriction.
- The restrictive PKU diet can be challenging and may lead to tyrosine deficiency.
- Tyrosine deficiency is implicated in neuropsychological issues observed in PKU patients.
Purpose of the Study:
- To evaluate the efficacy of tyrosine supplementation in PKU patients.
- To assess tyrosine's impact on intelligence, neuropsychological performance, growth, and quality of life.
- To determine if tyrosine supplementation is beneficial alongside or instead of a phenylalanine-restricted diet.
Main Methods:
- Systematic review of randomized and quasi-randomized controlled trials.
- Searched multiple databases and contacted manufacturers for relevant studies.
- Included trials involving tyrosine supplementation versus placebo in PKU patients.
Main Results:
- Three trials with 56 participants were included.
- Tyrosine supplementation significantly increased blood tyrosine concentrations.
- No significant differences were observed in other measured outcomes like intelligence or growth.
Conclusions:
- Current evidence does not support routine clinical use of tyrosine supplementation for PKU.
- Further randomized controlled studies are necessary to confirm benefits.
- This review will not be updated due to limited research activity in this area.
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