title: Biochemical and clinical effects of Whey protein supplementation in Parkinson's disease: A pilot study.
abstract: BACKGROUND
  Parkinson's disease (PD) is an oxidative stress-mediated degenerative disorder. Elevated plasma homocysteine (Hcy) is frequently found in the levodopa-treated PD patients, is associated with disease progression and is a marker of oxidative stress. Whey protein is a rich source of cysteine, and branched-chain amino acids (BCAA). It has been shown that supplementation with Whey protein increases glutathione synthesis and muscle strength.
  
  
  OBJECTIVE
  In this study, we conducted a placebo-controlled, double-blind study (NCT01662414) to investigate the effects of undenatured Whey protein isolate supplementation for 6months on plasma glutathione, plasma amino acids, and plasma Hcy in PD patients. Clinical outcome assessments included the unified Parkinson's disease rating scale (UPDRS) and striatal L-3,4-dihydroxy-6-(18)F-fluorophenylalanine (FDOPA) uptake were determined before and after supplementation. 15 patients received Whey protein, and 17 received Soy protein, served as a control group.
  
  
  RESULTS
  Significant increases in plasma concentration of reduced glutathione and the ratio of reduced to oxidized glutathione were found in the Whey-supplemented patients but not in a control group. This was associated with a significant decrease of plasma levels of Hcy. The plasma levels of total glutathione were not significantly changed in either group. Plasma BCAA and essential amino acids (EAA) were significantly increased in the Whey-supplemented group only. The UPDRS and striatal FDOPA uptake in PD patients were not significantly ameliorated in either group. However, significant negative correlation was observed between the UPDRS and plasma BCAA and EAA in the pre-supplemented PD patients.
  
  
  CONCLUSIONS
  This study is the first to report that Whey protein supplementation significantly increases plasma reduced glutathione, the reduced to oxidized glutathione ratio, BCAAs and EAAs in patients with PD, together with a concomitant significant reduction of plasma Hcy. However, there were no significant changes in clinical outcomes. Long-term, large randomized clinical studies are needed to explore the benefits of Whey protein supplementation in the management of PD patients.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Piyaratana
authors.initials: P
authors.lastname: Tosukhowong
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Chanchai
authors.initials: C
authors.lastname: Boonla
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Thasinas
authors.initials: T
authors.lastname: Dissayabutra
authors.affiliation: Chulalongkorn Center of Excellence for Parkinson's Disease and Related Disorders, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand.
authors.forename: Lalita
authors.initials: L
authors.lastname: Kaewwilai
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Sasipa
authors.initials: S
authors.lastname: Muensri
authors.affiliation: National Cyclotron and PET Center, Chulabhorn Hospital, Bangkok, Thailand.
authors.forename: Chanisa
authors.initials: C
authors.lastname: Chotipanich
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Juho
authors.initials: J
authors.lastname: Joutsa
authors.affiliation: Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland.
authors.forename: Juha
authors.initials: J
authors.lastname: Rinne
authors.affiliation: Chulalongkorn Center of Excellence for Parkinson's Disease and Related Disorders, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok 10330, Thailand; Department of Rehabilitation Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Roongroj
authors.initials: R
authors.lastname: Bhidayasiri
mesh_terms: D000596:Amino Acids / Q000097:blood; D000978:Antiparkinson Agents / Q000627:therapeutic use; D001921:Brain / Q000000981:diagnostic imaging; D019587:Dietary Supplements; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D005978:Glutathione / Q000097:blood; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood* / Q000000981:diagnostic imaging / Q000178:diet therapy* / Q000188:drug therapy; D010865:Pilot Projects; D000072078:Positron Emission Tomography Computed Tomography; D019275:Radiopharmaceuticals; D012720:Severity of Illness Index; D030262:Soybean Proteins / Q000008:administration & dosage; D016896:Treatment Outcome; D000067816:Whey Proteins / Q000008:administration & dosage*
chemical_list: D000596:Amino Acids; D000978:Antiparkinson Agents; D019275:Radiopharmaceuticals; D030262:Soybean Proteins; D000067816:Whey Proteins; D006710:Homocysteine; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; D005978:Glutathione
keywords: Homocysteine; Oxidative stress; Parkinson's disease; Plasma amino acid; Soy protein; Unified Parkinson's disease rating scale; Whey protein