title: Plasma pyridoxal 5'-phosphate in the US population: the National Health and Nutrition Examination Survey, 2003-2004.
abstract: BACKGROUND
  No large-scale, population-based study has considered the descriptive epidemiology of vitamin B-6 status with use of plasma pyridoxal 5'-phosphate (PLP), the indicator of vitamin B-6 adequacy used to set the current Recommended Dietary Allowance, which is < or = 2 mg/d for all subgroups.
  
  
  OBJECTIVE
  We sought to examine the epidemiology of vitamin B-6 status in the US population.
  
  
  METHODS
  In > 6000 participants aged > or = 1 y in the National Health and Nutrition Examination Survey (2003-2004), we considered relations between plasma PLP and various subject characteristics and examined trends in plasma PLP and homocysteine with vitamin B-6 intake, both overall and in selected subgroups.
  
  
  RESULTS
  In males, plasma PLP decreased with age after adolescence only in nonusers of supplemental vitamin B-6. Regardless of supplement use, plasma PLP concentrations of women of childbearing age were significantly lower than those of comparably aged men, and most oral contraceptive users had plasma PLP < 20 nmol/L. The prevalence of low plasma PLP was significantly > 3% at vitamin B-6 intakes from 2 to 2.9 mg/d in all subgroups and at intakes from 3 to 4.9 mg/d in smokers, the elderly, non-Hispanic blacks, and current and former oral contraceptive users. Intakes from 3 to 4.9 mg/d compared with < 2 mg/d were associated with significant protection from low plasma PLP in most subgroups and from hyperhomocysteinemia in the elderly.
  
  
  CONCLUSIONS
  Vitamin B-6 intakes of 3 to 4.9 mg/d appear consistent with the definition of a Recommended Dietary Allowance for most Americans. However, at that intake level, substantial proportions of some population subgroups may not meet accepted criteria for adequate vitamin B-6 status.
authors.affiliation: Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA. martha.morris@tufts.edu
authors.forename: Martha Savaria
authors.initials: MS
authors.lastname: Morris
authors.forename: Mary Frances
authors.initials: MF
authors.lastname: Picciano
authors.forename: Paul F
authors.initials: PF
authors.lastname: Jacques
authors.forename: Jacob
authors.initials: J
authors.lastname: Selhub
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D018673:Nutrition Policy; D009749:Nutrition Surveys; D009751:Nutritional Requirements; D009752:Nutritional Status; D011732:Pyridoxal Phosphate / Q000097:blood*; D012737:Sex Factors; D014481:United States; D025101:Vitamin B 6 / Q000008:administration & dosage* / Q000097:blood*; D026681:Vitamin B 6 Deficiency / Q000097:blood / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D006710:Homocysteine; D011732:Pyridoxal Phosphate; D025101:Vitamin B 6