Pyridoxic acid excretion during low vitamin B-6 intake, total fasting, and bed rest.
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.
Coburn
S P
SP
Biochemistry Department, Fort Wayne State Developmental Center, IN, USA.
Thampy
K G
KG
Lane
H W
HW
Conn
P S
PS
Ziegler
P J
PJ
Costill
D L
DL
Mahuren
J D
JD
Fink
W J
WJ
Pearson
D R
DR
Schaltenbrand
W E
WE
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*
D011735:Pyridoxic Acid; D011732:Pyridoxal Phosphate; D011736:Pyridoxine