Folate catabolite excretion is responsive to changes in dietary folate intake in elderly women.
BACKGROUND
The major route of folate turnover is by catabolic cleavage of the C9-N10 bond producing p-aminobenzoylglutamate (pABG) and its primary excretory form, p-acetamidobenzoylglutamate (ApABG). We hypothesize that total pABG (ApABG + pABG) excretion parallels both the mass of body folate pools from which these catabolites originate and the folate-status indicators.


OBJECTIVE
The objective was to determine whether urinary folate catabolite excretion reflects body pool size and parallels the static and functional measures of folate status.


METHODS
Urinary folate catabolite excretion was measured in women (aged 60-85 y) consuming controlled amounts of folate for 14 wk. A low-folate diet (120 microg/d) was consumed (n = 33) for 7 wk, and then subjects were randomly assigned to consume either 200 (n = 14) or 400 (n = 16) microg folate/d. Urinary pABG and ApABG concentrations were measured by HPLC at 0, 7, and 14 wk.


RESULTS
Urinary excretion of total pABG was significantly lower (P = 0.001) after depletion (73.9 +/- 4.7 nmol/d) than at baseline (115 +/- 12.7 nmol/d). This rate of decline (approximately 0.7% per day) is consistent with the kinetically measured rate of turnover of total body folate at moderate folate intakes. The average percentage increase in total pABG in response to folate repletion with 400 microg/d (75%) was significant (P = 0.02). Folate catabolite excretion was significantly (P = 0.0001) associated with serum and red blood cell folate, plasma homocysteine, and DNA hypomethylation after depletion and with serum folate (P = 0.001) and plasma homocysteine (P = 0.0002) after repletion with 400 microg folate/d.


CONCLUSIONS
Total urinary pABG excretion reflects total body folate pool size and is a long-term indicator that parallels functional measures of folate status.
Wolfe
Judith M
JM
Food Science and Human Nutrition Department, College of Agricultural and Life Sciences, University of Florida, Gainesville 32611, USA.
Bailey
Lynn B
LB
Herrlinger-Garcia
Kelli
K
Theriaque
Douglas W
DW
Gregory
Jesse F
JF
Kauwell
Gail P A
GP
D010129:4-Aminobenzoic Acid / Q000652:urine; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D019175:DNA Methylation; D004032:Diet; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood / Q000652:urine*; D005971:Glutamates / Q000652:urine; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D009752:Nutritional Status; D062366:para-Aminobenzoates
D005971:Glutamates; D062366:para-Aminobenzoates; D006710:Homocysteine; C030903:N-(4-acetamidobenzoyl)-L-glutamic acid; D005492:Folic Acid; C011398:4-aminobenzoylglutamic acid; D010129:4-Aminobenzoic Acid