title: High dietary folate supplementation: effects on diet utilization and methionine metabolism in aged rats.
abstract: BACKGROUND
  Folate supplementation or food fortification is being nowadays recommended because of its effect on the prevention of neural tube defects and the lowering of homocysteine levels. We have previously reported a negative effect of high dose folate supplementation on dietary metabolic protein utilization in pregnant and virgin rats.
  
  
  OBJECTIVE
  To determine the effects of such folate supplementation on nutritional and some biochemical markers in aged rats.
  
  
  METHODS
  Aged male Wistar rats were given free access either to a folate supplemented diet (40 mg/kg diet) or a control diet (1 mg/kg diet) for 29 days following a week adaptation period. Two critical periods were used for metabolic balance studies (experimental days 1 to 8 and 22 to 29), involving the determination of digestive and metabolic protein utilization. Several biochemical markers involved in the methylation cycle were also determined.
  
  
  RESULTS
  Data show that long term high folate supplementation reduces nitrogen digestive function in aged rats (P<0,03) during the second metabolic period (days 22 to 29). However, supplementation did not alter metabolic protein utilization. Plasma homocysteine and serum vitamin B6 and B12 levels, hepatic S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations -and thus methylation ratio, SAM/SAH-, were neither affected by folate supplementation.
  
  
  CONCLUSIONS
  Folate supplementation at high doses may have a negative effect on diet utilization, related to protein status.
authors.affiliation: Sección de Nutrición y Bromatología, Departamento de Ciencias Biomédicas I, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid, Spain. achontu@ceu.es
authors.forename: M
authors.initials: M
authors.lastname: Achon
authors.forename: E
authors.initials: E
authors.lastname: Alonso-Aperts
authors.forename: G
authors.initials: G
authors.lastname: Varela-Moreiras
mesh_terms: D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000652:urine; D019175:DNA Methylation; D004041:Dietary Fats / Q000378:metabolism; D004044:Dietary Proteins / Q000097:blood / Q000652:urine; D019587:Dietary Supplements; D005492:Folic Acid / Q000008:administration & dosage*; D008297:Male; D008715:Methionine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015415:Biomarkers; D004041:Dietary Fats; D004044:Dietary Proteins; D005492:Folic Acid; D008715:Methionine