Validation of an FFQ to estimate the intake of fatty acids using erythrocyte membrane fatty acids and multiple 3d dietary records.

Objective: The estimation of dietary intake in population-based studies is often assessed by the FFQ. The objective of our study is to evaluate the validity of an FFQ used to assess dietary fatty acid intake among middle-aged Chinese adults in Southern China.
Design: The method of triads was applied to obtain the validity coefficients (VC) of the FFQ for specific fatty acids. A subsample was randomly selected from an earlier cross-sectional study. The FFQ and 3d dietary records were used for dietary assessment, and the fatty acid composition of erythrocyte membranes was determined as the biomarker.
Results: The Spearman correlation coefficients between the FFQ and 3d dietary records were moderate to good (r = 0.28-0.66). The VC of the FFQ estimated by the method of triads were 0.72, 0.61, 0.65, 0.75 and 0.67 for MUFA, total n-6 fatty acids, alpha-linolenic acid, EPA and DHA, respectively. The VC could not be calculated for SFA, PUFA and total n-3 fatty acids because of negative correlations among the three measurements. But, the correlations between the FFQ and the dietary records were moderate for these fatty acids.
Conclusions: Our FFQ applied in Southern Chinese adults was valid to estimate their dietary fatty acid intake and was thus suitable for use in a large cohort study.