title: Amino acid supplementation in l-dopa treated Parkinson's disease patients.
abstract: BACKGROUND
  The correlation between Parkinson disease and malnutrition is well established, however a protein-restricted diet is usually prescribed because of potentially negative interactions between dietary amino acids and l-dopa pharmacokinetics. This strategy could increase the risk of further nutritional deficits.
  
  
  METHODS
  A monocentric, prospective, randomized, double-blind pilot study was performed on two groups of Parkinson-affected, protein-restricted, patients: Intervention (n = 7; amino acid supplementation twice daily) and Placebo (n = 7; placebo supplementation twice daily). At enrolment, after 3- and 6-month supplementation, neurological evaluations (UPDRS III, Hoenh-Yahr scale, l-dopa equivalent dose assessment) were performed and blood sample was collected to define insulin sensitivity (QUICKI index) and oxidative stress (oxidized and reduced glutathione). Repeated measure ANCOVA was applied to define time effect and time × treatment interaction.
  
  
  RESULTS
  Participants were comparable at baseline for all assessed parameters. Neurological outcomes and l-dopa requirement were comparable in both group after 6-month of supplementation, without time × treatment interaction. The decrease in insulin sensitivity, as assessed by QUICKI index, observed after 6 months in both groups, was greater in Placebo than in Intervention (time effect p < 0.001; time × treatment interaction p = 0.01). Moreover, despite no changes in total erythrocyte glutathione concentrations, oxidized glutathione levels decreased by 28 ± 17% in the Intervention while increased by 55 ± 38% in Placebo (time effect p = 0.05; time × treatment interaction p = 0.05), after 6-month supplementation.
  
  
  CONCLUSIONS
  Amino acid supplementation, assumed with shrewd temporal distribution, did not show detrimental effects on neurological and pharmacological control in protein-restricted Parkinson-affected patients, chronically treated with l-dopa. Furthermore, daily amino acid supplementation partially counteracted insulin resistance development and the loss in antioxidant availability.
authors: University of Udine, Clinica Neurologica, Department of Experimental and Clinical Medical Sciences, Italy.
authors: A
authors: A
authors: Cucca
authors: University of Trieste, Clinica Medica, Department of Medical, Surgical and Health Sciences, Italy.
authors: S
authors: S
authors: Mazzucco
authors: University of Trieste, Clinica Neurologica, Department of Medical, Surgical and Health Sciences, Italy.
authors: A
authors: A
authors: Bursomanno
authors: University of Trieste, Clinica Neurologica, Department of Medical, Surgical and Health Sciences, Italy.
authors: L
authors: L
authors: Antonutti
authors: University of Trieste, Clinica Medica, Department of Medical, Surgical and Health Sciences, Italy.
authors: F G
authors: FG
authors: Di Girolamo
authors: University of Trieste, Clinica Neurologica, Department of Medical, Surgical and Health Sciences, Italy.
authors: G
authors: G
authors: Pizzolato
authors: University of Trieste, Clinica Neurologica, Department of Medical, Surgical and Health Sciences, Italy.
authors: N
authors: N
authors: Koscica
authors: University of Udine, Clinica Neurologica, Department of Experimental and Clinical Medical Sciences, Italy.
authors: G L
authors: GL
authors: Gigli
authors: University of Trieste, Clinica Neurologica, Department of Medical, Surgical and Health Sciences, Italy.
authors: M
authors: M
authors: Catalan
authors: University of Trieste, Clinica Medica, Department of Medical, Surgical and Health Sciences, Italy. Electronic address: biolo@units.it.
authors: G
authors: G
authors: Biolo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000008:administration & dosage*; D001786:Blood Glucose / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D018753:Diet, Protein-Restricted; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D007980:Levodopa / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D018384:Oxidative Stress; D010300:Parkinson Disease / Q000188:drug therapy*; D010865:Pilot Projects; D011446:Prospective Studies; D016896:Treatment Outcome; D014280:Triglycerides / Q000097:blood
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007328:Insulin; D014280:Triglycerides; D007980:Levodopa; D002097:C-Reactive Protein; D005978:Glutathione
keywords: Amino acid supplementation; Insulin sensitivity; Motor fluctuations; Parkinson's disease; l-Dopa treatment