Correlation of folate catabolites in spot urine with 24 hour urine and blood folate concentrations.

<p><b><i>Comparison of folate catabolites in spot urine and 24 hour urine.</i></b> Creatinine normalized concentration of para-aminobenzoylglutamate (pABG) (A) and para-acetamidobenzoylglutamate (apABG) (B) in spot urine is correlated with daily excretion in 24 hour urine. <b><i>Correlations of urinary pABG with plasma and red blood cell folate, a comparison between baseline and week 12.</i></b> Scatterplots for para-aminobenzoylglutamate (pABG)/creatinine in spot urine related to plasma folate and red blood cell folate concentrations, at baseline (C, E, n = 51) and week 12 (D, F, n = 25). For ease of comparison, dashed lines in C, D, E and F indicate the lowest value of the respective biomarker at week 12.</p

Time course of plasma, red blood cell folate, urinary pABG and apABG during folic acid supplementation.

<p>Time course of the median concentrations (error bars = inter quartile range (IQR)) of plasma folate (nmol/L) (A), red blood cell folate (nmol/L) (B), pABG (nmol/mmol creatinine) (C) and apABG (nmol/mmol creatinine) (D) during folic acid supplementation. Significant changes from baseline: *: p = 0.005 and **: p≤0.001 (Wilcoxon’s test).</p

Description of participants and biochemical parameters during habitual diet (baseline).

<p>Values are given as median, IQR in parentheses. Results of the two baseline measurements were averaged, if valid data were available from both examinations. Relations between variables were analyzed by Spearman’s rank correlation. Significance level:</p>*<p>p<0.05,</p>**<p>p<0.001. pABG: para-aminobenzoylglutamate, apABG: para-acetamidobenzoylglutamate, MMA: methylmalonic acid, ratio_p/ap: ratio of pABG to apABG.</p>†<p>One extreme outlier was excluded.</p

Time course of urinary apABG and pABG after folic acid intake (short-term study).

<p>Time course (medians, error bars = inter quartile range (IQR)) of urinary apABG (nmol/mmol creatinine) (A) and pABG (nmol/mmol creatinine) (B), in fasted state (black line) and after oral intake of 400 µg folic acid (dashed line) during the first three hours. (C) Time course of the ratio between pABG and apABG (ratio_p/ap) in spot urine without (black) and with (dashed line) intake of folic acid at time 0. Significant differences from time point 0 are marked with an asterisk (*: p≤0.05, Wilcoxon’s test). (D) Histograms of observed frequencies of ratio_p/ap in spot urine in non-dosed state (light grey bars) and 2 h after oral folate intake (dark grey bars), displayed with continuous kernel density function estimates (black lines).</p

RCF, PF, urinary folate catabolites during folic acid supplementation (week 6, 12).

<p>Values are given as median and IQR in parentheses, relations between variables were analyzed by Spearman’s rank correlation. pABG: para-aminobenzoylglutamate, apABG: para-acetamidobenzoylglutamate, RCF: red blood cell folate, PF: plasma folate. Spearman’s rank correlation significance level:</p>*<p>p<0.05. Significance of changes from baseline was calculated using Wilcoxon’s test and given as p-value.</p

Flow chart of study selection process.

<p>Flow chart of study selection process.</p