Validity of food and nutrient intakes assessed by a food frequency questionnaire among Chinese adults

Background Studies regarding the validity of the food frequency questionnaire (FFQ) and the food composition table (FCT) are limited in Asian countries. We aimed to evaluate the validity of a 64-item FFQ and different methods of constructing the FFQ FCTs for assessing dietary intakes of foods and nutrients among adults in eastern China. Methods A total of 2325 participants (aged 56.2 ± 14.9 years, 51.6% female) from nine cities in Zhejiang province who completed a 64-item FFQ and 3-day 24-hour dietary recalls (24HRs) in 2015 were included. Eight FFQ FCTs were generated covering food items and specific weights estimated using professional knowledge, representative 24HRs data, or the Chinese FCT (CFCT). Energy-adjusted intakes of foods and nutrients were estimated by residual and energy density methods. Spearman correlation coefficients (SCCs) of intakes of 14 food groups and 17 nutrients between FFQ and 24HRs were calculated to evaluate the overall validity of FFQ. Results The average intakes of most food groups and nutrients assessed with FFQ were higher than those assessed using the 24HRs. For the food groups, the averaged energy-adjusted (residual method) SCC between FFQ and 24HRs was 0.27, ranging from 0.14 (starch-rich beans) to 0.49 (aquatic products). For nutrient assessment, the weighted FCT (WFCT) performs the best, and the averaged energy-adjusted (residual method) SCC was 0.26, ranging from 0.16 (iron) to 0.37 (potassium). Similar correlations with 24HRs were observed when using other FFQ FCT in the calculation of nutrient intakes. Conclusion The 64-item Chinese FFQ and the WFCT were reasonably valid to assess the dietary intakes of certain foods and nutrients among adults in eastern China.