Validity of a diet history questionnaire estimating β-carotene, vitamin C and α-tocopherol intakes in Japanese pregnant women

We investigated the validity and reproducibility of a self-administered diet history questionnaire (DHQ) that estimates the intakes of β-carotene, vitamin C and α-tocopherol. Ninety-five healthy women with singleton pregnancies in the second trimester were examined at a university hospital in Tokyo. The intakes of β-carotene, vitamin C and α-tocopherol assessed by the DHQ were compared to the corresponding serum concentrations. To assess the reproducibility, 58 pregnant women completed it in two sessions within a 4-5 week interval. We found significantly positive correlations between the energy-adjusted intakes and serum concentrations of β-carotene and vitamin C (r = 0.254 and r = 0.323, respectively). However, α-tocopherol intake was not associated with the corresponding serum concentration. The intraclass correlation coefficients of the two-time DHQ were 0.743 (β-carotene), 0.665 (vitamin C) and 0.718 (α-tocopherol). DHQ has acceptable validity and reproducibility for β-carotene and vitamin C intakes in Japanese pregnant women.