Validity of a 98-item Food Frequency Questionnaire for the Japan Nurses’ Health Study

Background & Aims: We developed a 98-item semi-quantitative Food Frequency Questionnaire (FFQ) for participants in the Japan Nurses’ Health Study (JNHS) to examine habitual dietary and nutrient intake among working women. The validity of the developed FFQ was examined on the basis of two 7-day diet records (7dDRs; 14 records in total).Methods: The 7dDRs were provided by 36 female nurses from August to October 2007 and February to April 2008. A semi-quantitative 98-item FFQ (JNHS-FFQ) was administered in October 2007, and the two 7dDRs were used to evaluate its validity.Results: The validity of the JNHS-FFQ was examined on the basis of the dietary intakes documented in the two 7dDRs. The median Pearson’s correlation coefficient was 0.39 for crude total energy intake and 0.34 for energy-adjusted intake. The energy intake estimated from the JNHS-FFQ was higher than the actual intake according to the DRs, and the correlation coefficients between the DRs and JNHS-FFQ data ranged from -0.04 (iodine) to 0.62 (copper) for crude intakes and -0.12 (zinc) to 0.56 (polyunsaturated fat) for energy-adjusted intakes.Conclusions: The JNHS-FFQ is useful for epidemiological studies aiming to estimate the nutrient intakes of Japanese working women.