title: Pyridoxic acid excretion during low vitamin B-6 intake, total fasting, and bed rest.
abstract: Vitamin B-6 metabolism in 10 volunteers during 21 d of total fasting was compared with results from 10 men consuming a diet low only in vitamin B-6 (1.76 mumol/d) and with men consuming a normal diet during bed rest. At the end of the fast mean plasma concentrations of vitamin B-6 metabolites and urinary excretion of 4-pyridoxic acid tended to be higher in the fasting subjects than in the low-vitamin B-6 group. The fasting subjects lost approximately 10% of their total vitamin B-6 pool and approximately 13% of their body weight. The low-vitamin B-6 group lost only approximately 4% of their vitamin B-6 pool. Compared with baseline, urinary excretion of pyridoxic acid was significantly increased during 17 wk of bed rest. There was no increase in pyridoxic acid excretion during a second 15-d bed rest study. These data suggest the possibility of complex interactions between diet and muscle metabolism that may influence indexes that are frequently used to assess vitamin B-6 status.
authors.affiliation: Biochemistry Department, Fort Wayne State Developmental Center, IN, USA.
authors.forename: S P
authors.initials: SP
authors.lastname: Coburn
authors.forename: K G
authors.initials: KG
authors.lastname: Thampy
authors.forename: H W
authors.initials: HW
authors.lastname: Lane
authors.forename: P S
authors.initials: PS
authors.lastname: Conn
authors.forename: P J
authors.initials: PJ
authors.lastname: Ziegler
authors.forename: D L
authors.initials: DL
authors.lastname: Costill
authors.forename: J D
authors.initials: JD
authors.lastname: Mahuren
authors.forename: W J
authors.initials: WJ
authors.lastname: Fink
authors.forename: D R
authors.initials: DR
authors.lastname: Pearson
authors.forename: W E
authors.initials: WE
authors.lastname: Schaltenbrand
mesh_terms: D000328:Adult; D001510:Bed Rest; D004032:Diet; D005215:Fasting / Q000097:blood / Q000652:urine*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000097:blood; D011735:Pyridoxic Acid / Q000097:blood / Q000652:urine*; D011736:Pyridoxine / Q000493:pharmacokinetics*; D026681:Vitamin B 6 Deficiency / Q000097:blood / Q000652:urine*
chemical_list: D011735:Pyridoxic Acid; D011732:Pyridoxal Phosphate; D011736:Pyridoxine