Table 4

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

Corresponding serum concentrations

Agreement (% classified into the same or adjacent quintile)¹

Discordance (% classified into the opposite quintile)¹

Linear trend²

p

1^st quintile

2^nd quintile

3^rd quintile

4^th quintile

5^th 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

Folate and vitamin B₁₂ intakes were assessed by a self-administered diet history questionnaire (DHQ)

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.

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

Shiraishi et al. Nutrition Journal 2012 11:15   doi:10.1186/1475-2891-11-15