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Table 4 Mean intakes in each quintile based on corresponding serum concentrations and cross-classification between quintiles of intakes and serum concentrations (n = 167)

From: Validity and reproducibility of folate and vitamin B12 intakes estimated from a self-administered diet history questionnaire in Japanese pregnant women

  Corresponding serum concentrations Agreement (% classified into the same or adjacent quintile)1 Discordance (% classified into the opposite quintile)1 Linear trend2
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  1st quintile 2nd quintile 3rd quintile 4th quintile 5th quintile    
  Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD    
Intakes         
   Folate [μg/day] 209 ± 96 258 ± 91 249 ± 91 286 ± 101 296 ± 134 64.7 4.8 0.003
[μg/1,000 kcal] 115 ± 39 145 ± 46 139 ± 49 145 ± 35 164 ± 58 61.1 3.6 0.002
Vitamin B12 [μg/day] 4.62 ± 2.43 6.36 ± 4.20 6.02 ± 2.91 4.88 ± 1.81 6.82 ± 3.17 54.5 4.2 0.029
[μg/1,000 kcal] 2.57 ± 1.29 3.23 ± 1.68 3.20 ± 1.24 2.90 ± 0.84 3.58 ± 1.41 59.9 4.2 0.005
  1. Folate and vitamin B12 intakes were assessed by a self-administered diet history questionnaire (DHQ)
  2. 1Agreement and discordance in quintile ranking was assessed as the percentage classification for the pregnant women based on intake and corresponding serum concentration in the same, adjacent, and opposite quintiles.
  3. 2Linear regression analyses were performed to test for significant linear trends between intakes and serum concentrations, adjusting for research settings. The dependent variables were log-transformed