Dietary and biochemical assessment of the folate status of a group of young women of childbearing potentia

A sample of 229 young women of childbearing potential (14-20 years) was recruited from Southern Ontario to: (1) estimate intakes of folate and vitamin $rm Bsb{12}$ using a food frequency questionnaire (FFQ) and a 3-day weighed food record (3d-WFR) and to compare these intake estimates with biochemical indices; (2) explore the vitamin determinants (folate and vitamin $rm Bsb{12}$) of serum homocysteine; and (3) determine the effect of oral contraceptive agents (OCA), tobacco, and alcohol use on serum folate, homocysteine and vitamin $rm Bsb{12}$ as well as red blood cell (RBC) and buccal cell folate.;Using cut-off values of 6.7 nmol/L for serum folate, 317 nmol/L for RBC folate, and 118 pmol/L for serum vitamin $rm Bsb{12}$: 11.3% (n = 25/221), 2.9% (n = 3/108) and 4.9% (n = 11/224) of participants, respectively, had blood concentrations indicative of folate and vitamin $rm Bsb{12}$ deficiency. Using 15 $rmmu mol/L$ as a cut-off for serum homocysteine, 1.6% (n = 3/188) of participants had elevated homocysteine concentrations.;Median folate and $rm Bsb{12}$ intakes estimated from the FFQ were larger than those from the 3d-WFR (572 versus 386 $rmmu g/day$ and 4.9 versus 1.9 $rmmu g/day,$ respectively; n = 105). Correlation coefficients between the 3d-WFR and serum and RBC folate were r = 0.65, $P < 0.01;$ r = 0.50, $P < 0.01,$ respectively and those for the FFQ were r = 0.48, $P < 0.01;$ r = 0.42, $P < 0.01,$ respectively. The correlations between serum vitamin $rm Bsb{12}$ and $rm Bsb{12}$ intake estimated from the 3d-WFR and the FFQ were r = 0.32, $P < 0.01$ and r = 0.25, $P < 0.05,$ respectively. Excluding supplement users decreased these correlations but all associations remained significant except the association between serum $rm Bsb{12}$ and $rm Bsb{12}$ intake as estimated by the FFQ.;Folate intake (r = -0.25, $P < 0.001)$ but not $rm Bsb{12}$ was inversely associated with serum homocysteine concentration. RBC folate (r = -0.36, P = 0.003) and serum $rm Bsb{12}$ (r = -0.36, $P < 0.01)$ but not serum folate (r = -0.12, $P = 0.1119)$ were inversely associated with serum homocysteine concentrations. Multiple regression analysis, which included folate intake as a covariate, revealed that OCA use (n = 48), alcohol use (n = 139) and smoking (n = 38) were not significantly associated with serum folate or RBC folate levels. Serum vitamin $rm Bsb{12}$ levels were not associated with smoking or alcohol but were on average 33% lower in OCA users than non-users. Serum homocysteine levels were not associated with smoking or OCA use but were on average 13% higher in alcohol users than nonusers.;The present findings suggest that in young women of child bearing potential: (1) the FFQ and 3d-WFR give different estimates of folate and $rm Bsb{12}$ intake; (2) the FFQ and 3d-WFR are valid measures of assessing vitamin $rm Bsb{12}$ and folate intake; (3) RBC folate, serum $rm Bsb{12},$ and folate intakes but not serum folate are negatively associated with serum homocysteine; (4) currently available OCAs and smoking do not have a negative impact on biochemical folate indices; (5) OCAs do have a negative impact on serum $rm Bsb{12}$ concentrations; and (6) although alcohol use was not associated with serum and RBC folate, it appears to be associated with higher homocysteine concentrations. (Abstract shortened by UMI.).