title: Betaine as a determinant of postmethionine load total plasma homocysteine before and after B-vitamin supplementation.
abstract: OBJECTIVE
  Betaine is a substrate in the betaine-homocysteine methyltransferase reaction, converting homocysteine to methionine. There are only sparse data on plasma betaine as a determinant of the plasma total homocysteine (tHcy) concentration.
  
  
  RESULTS
  Ninety patients undergoing coronary angiography were randomized into 4 groups administered oral: (1) folic acid (0.8 mg), vitamin B12 (0.4 mg), and vitamin B6 (40 mg); (2) folic acid and vitamin B12; (3) vitamin B6 alone; or (4) placebo. Nonfasting blood samples were collected at baseline and 3, 14, and 28 days and 3, 6, and 12 months after treatment start. A 4-hour methionine-loading test (0.1 g/kg) was performed at baseline and after 3 months. At baseline, median (interquartile range) plasma betaine was 36.9 micromol/L (range: 30.3 to 46.8) and was increased by 15% after methionine loading. The postmethionine load (PML) increase in tHcy was inversely related to plasma betaine (beta=-0.29, P=0.02) and even more strongly to PML betaine (beta=-0.47, P<0.001). After 3 months of intervention, the relation between the PML increase in tHcy and PML betaine was weakened (beta=-0.33, P=0.007).
  
  
  CONCLUSIONS
  Plasma betaine is a strong determinant of the PML increase in tHcy in subjects not supplemented with B-vitamins.
authors.affiliation: Locus for Homocysteine and Related Vitamins, University of Bergen, N-5021 Bergen, Norway.
authors.forename: Pål I
authors.initials: PI
authors.lastname: Holm
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Bleie
authors.forename: Per M
authors.initials: PM
authors.lastname: Ueland
authors.forename: Ernst A
authors.initials: EA
authors.lastname: Lien
authors.forename: Helga
authors.initials: H
authors.lastname: Refsum
authors.forename: Jan E
authors.initials: JE
authors.lastname: Nordrehaug
authors.forename: Ottar
authors.initials: O
authors.lastname: Nygård
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001622:Betaine / Q000097:blood / Q000378:metabolism*; D002794:Choline / Q000097:blood; D017023:Coronary Angiography; D019587:Dietary Supplements; D004334:Drug Administration Schedule; D005215:Fasting; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage; D005500:Follow-Up Studies; D006710:Homocysteine / Q000097:blood* / Q000378:metabolism; D006801:Humans; D008297:Male; D008715:Methionine / Q000097:blood / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism; D008875:Middle Aged; D012521:Sarcosine / Q000031:analogs & derivatives* / Q000097:blood; D012737:Sex Factors; D014805:Vitamin B 12 / Q000008:administration & dosage; D025101:Vitamin B 6 / Q000008:administration & dosage; D014803:Vitamin B Complex / Q000008:administration & dosage*
chemical_list: D006710:Homocysteine; D014803:Vitamin B Complex; D001622:Betaine; C025138:dimethylglycine; D025101:Vitamin B 6; D005492:Folic Acid; D008715:Methionine; D008780:Methyltransferases; D002794:Choline; D014805:Vitamin B 12; D012521:Sarcosine