Research
L-Phenylalanine
14 peer-reviewed studies curated from PubMed and Semantic Scholar.
Studies
Sorted by quality and recency
Emerging therapeutic and cosmeceutical applications of phenylalanine and its metabolites.
This systematic review examines the pharmacological and cosmetic applications of phenylalanine and its metabolites, highlighting their antioxidant, antimicrobial, anti-inflammatory, and neuromodulatory properties. The review suggests potential benefits for skin health, pigmentation regulation, microbiome modulation, and mood-related dermatoses.
Effects of L-Phenylalanine on Energy Intake and Glycaemia-Impacts on Appetite Perceptions, Gastrointestinal Hormones and Gastric Emptying in Healthy Males.
This study evaluated the effects of intragastric L-phenylalanine on appetite perceptions, energy intake, and glycaemic response in 16 healthy, lean males. Phe-10 g stimulated plasma CCK and suppressed energy intake, while both Phe-10 g and Phe-5 g stimulated insulin and glucagon. Phe-10 g reduced plasma glucose levels in response to a mixed-nutrient drink, but phenylalanine had no effect on gastric emptying.
A randomised placebo controlled exploratory study of vitamin B-12, lofepramine, and L-phenylalanine (the "Cari Loder regime") in the treatment of multiple sclerosis.
A randomised placebo-controlled study on the 'Cari Loder regime' involving vitamin B-12, lofepramine, and L-phenylalanine in multiple sclerosis patients. The study found that patients improved by 2 GNDS points after starting vitamin B-12 injections, with an additional 0.6 points improvement from lofepramine and L-phenylalanine.
The effects of phenylalanine on exercise-induced fat oxidation: a preliminary, double-blind, placebo-controlled, crossover trial.
A double-blind, placebo-controlled, crossover trial with six healthy male volunteers examined the effects of phenylalanine supplementation on exercise-induced fat oxidation. Phenylalanine intake increased plasma glycerol and glucagon concentrations and decreased the respiratory exchange ratio during exercise, suggesting enhanced fat oxidation.
Effects of L-phenylalanine on energy intake in overweight and obese women: interactions with dietary restraint status.
RCT examining the effects of L-phenylalanine on energy intake in overweight and obese women. No overall effect was found, but interactions with dietary restraint status were detected. Energy intake was 11% lower following high-dose Phe for women with low rigid restraint, while no effects were noted for others. High-dose Phe increased nausea ratings, but reduced intake was noted only for those with low nausea ratings.
Dietary restraint and menstrual cycle phase modulated L-phenylalanine-induced satiety.
RCT examining the effects of L-phenylalanine on satiety in women across menstrual cycle phases. L-phenylalanine reduced daily energy intake by 9% compared to control, with greater effects in the follicular phase for women with low dietary restraint. The study suggests that menstrual cycle phase and dietary restraint status modulate the satiety response to L-phenylalanine.
Effect of L-phenylalanine supplementation and a high-protein diet on pharmacokinetics of cefdinir in healthy volunteers: an exploratory study.
Exploratory study on the effect of L-phenylalanine supplementation and a high-protein diet on the pharmacokinetics of cefdinir in six healthy male volunteers. The study found no changes in plasma concentrations and urinary excretion of cefdinir, suggesting that L-phenylalanine and high-protein diet do not upregulate intestinal and renal oligopeptide transport in the examined dose and duration.
MRI changes in multiple sclerosis following treatment with lofepramine and L-phenylalanine.
A randomized placebo-controlled trial involving 15 MS inpatients, with 8 receiving lofepramine and L-phenylalanine and 7 on placebo. The active group showed a significant reduction in lesion number on T1-weighted MRI scans compared to placebo. Ventricular volume increased less in the treated group, correlating with changes in MS-related symptoms and activities of daily living scores.
L-phenylalanine and UVA irradiation in the treatment of vitiligo.
An open trial with 149 patients over 18 months and a double-blind trial with 32 patients over 6 months evaluated the efficacy of L-phenylalanine combined with UVA therapy for vitiligo. Oral L-Phe loading resulted in peak plasma levels and a slight increase in plasma tyrosine. Positive response with various grades of repigmentation was observed, with optimal L-Phe dose being lower than 50 mg/kg/day.
Oral and topical L-phenylalanine, clobetasol propionate, and UVA/sunlight--a new study for the treatment of vitiligo.
Open trial on 70 patients with evolutive vitiligo treated with oral and topical L-phenylalanine, sunlight or UVA lamps, and clobetasol propionate. 90.9% showed improvement, with 68.5% achieving 75% or more improvement, especially on the face. No biochemical abnormalities were found.
Phenylalanine alters the mean power frequency of electroencephalograms and plasma L-dopa in treated patients with phenylketonuria.
Blinded, cross-over study in 8 older patients with phenylketonuria examining the effects of phenylalanine on brain function. Elevated plasma phenylalanine was associated with decreased mean power frequency of electroencephalograms and plasma L-DOPA, indicating reversible negative effects on brain electrical function.
Treatment of attention deficit disorder with DL-phenylalanine.
Nineteen patients with attention deficit disorder were given a 2-week double-blind crossover of DL-phenylalanine versus placebo. Thirteen subjects completed the study, showing significant improvement in mood and mood lability. However, benefits were lost within 3 months on open drug, and L-phenylalanine produced no clinical effect.
Regulation of pancreatic and gallbladder function by absorption of intrajejunal phenylalanine in man.
The study investigated the effects of varying loads of intraduodenal L-phenylalanine on pancreatic and gallbladder function in 32 healthy volunteers. L-phenylalanine absorption in the proximal jejunum increased pancreatic secretion and bilirubin outputs, with a significant correlation between pancreatic secretion and L-phenylalanine absorption rates.
[Metabolic changes in aromatic amino acids and monoamines in infantile autism and development of new treatment related to the finding].
The study developed a method using stable isotopes to measure turnover rates of aromatic amino acids in autistic patients. Disturbances in phenylalanine and tryptophan uptake were found, suggesting decreased supply to the brain. Treatments with L-DOPA, 5 HTP, and R-THBP showed mixed effects, with some patients improving and others experiencing symptom aggravation.