title: Betaine is as effective as folate at re-synthesizing methionine for protein synthesis during moderate methionine deficiency in piglets.
abstract: OBJECTIVE
  Both folate and betaine (synthesized from choline) are nutrients used to methylate homocysteine to reform the amino acid methionine following donation of its methyl group; however, it is unclear whether both remethylation pathways are of equal importance during the neonatal period when remethylation rates are high. Methionine is an indispensable amino acid that is in high demand in neonates not only for protein synthesis, but is also particularly important for transmethylation reactions, such as creatine and phosphatidylcholine synthesis. The objective of this study was to determine whether supplementation with folate, betaine, or a combination of both can equally re-synthesize methionine for protein synthesis when dietary methionine is limiting.
  
  
  METHODS
  Piglets were fed a low methionine diet devoid of folate, choline, and betaine, and on day 6, piglets were supplemented with either folate, betaine, or folate + betaine (n = 6 per treatment) until day 10. [1-13C]-phenylalanine oxidation was measured as an indicator of methionine availability for protein synthesis both before and after 2 days of supplementation.
  
  
  RESULTS
  Prior to supplementation, piglets had lower concentrations of plasma folate, betaine, and choline compared to baseline with no change in homocysteine. Post-supplementation, phenylalanine oxidation levels were 20-46 % lower with any methyl donor supplementation (P = 0.006) with no difference among different supplementation groups. Furthermore, both methyl donors led to similarly lower concentrations of homocysteine following supplementation (P < 0.05).
  
  
  CONCLUSIONS
  These data demonstrate an equal capacity for betaine and folate to remethylate methionine for protein synthesis, as indicated by lower phenylalanine oxidation.
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.
authors.forename: Laura E
authors.initials: LE
authors.lastname: McBreairty
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Robinson
authors.affiliation: Diabetes and Nutritional Sciences Division, King's College London, London, SE1 9NH, United Kingdom.
authors.forename: Scott V
authors.initials: SV
authors.lastname: Harding
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.|Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada.
authors.forename: Edward W
authors.initials: EW
authors.lastname: Randell
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.
authors.forename: Janet A
authors.initials: JA
authors.lastname: Brunton
authors.affiliation: Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada. rbertolo@mun.ca.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Bertolo
mesh_terms: D000818:Animals; D001622:Betaine / Q000008:administration & dosage / Q000097:blood*; D002247:Carbon Isotopes / Q000097:blood; D002794:Choline / Q000008:administration & dosage / Q000097:blood; D003545:Cysteine / Q000097:blood; D004032:Diet; D019587:Dietary Supplements; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood*; D006710:Homocysteine / Q000097:blood; D008715:Methionine / Q000096:biosynthesis* / Q000097:blood / Q000172:deficiency*; D008954:Models, Biological; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000097:blood; D014176:Protein Biosynthesis; D013552:Swine
chemical_list: D002247:Carbon Isotopes; D006710:Homocysteine; D001622:Betaine; D010649:Phenylalanine; D005492:Folic Acid; D008715:Methionine; D003545:Cysteine; D002794:Choline
keywords: 1-Carbon metabolism; Betaine; Folate; Piglet; Protein synthesis