Validation study of fatty acid consumption assessed with a short food frequency questionnaire against plasma concentration in middle-aged Japanese people

Objective: To assess the relative validity of data for consumption of fatty acids (FAs) measured with a short food frequency questionnaire (FFQ) in comparison with plasma concentration of FAs. Design: In this cross-sectional study, completed FFQs were secured from 177 (92 male and 85 female) employees working for a company in August 2001. Intake of FAs was assessed with the FFQ, and the values were validated against FA concentration in plasma in overnight-fasting blood. Results: Mean9/SD daily intakes of total fatty acids (TFAs) were 44.49/8.0 g day-1 for men and 42.99/7.2 g day-1 for women. Plasma concentration of TFAs were 12.739/3.78 mmol l-1 for men and 10.549/1.75 mmol l-1 for women. Spearman’s rank correlation coefficients, unadjusted and energy-adjusted by the energy-density method and residual method, for n-3 highly unsaturated fatty acids (HUFAs) were 0.37 (p<0.001), 0.38 (p<0.001) and 0.40 (p<0.001) for men, and 0.41 (p<0.001), 0.26 (p<0 .01) and 0.29 (p<0.01) for women, respectively. Conclusions: Relative validity values of data for intake of n-3 polyunsaturated fatty acids (PUFAs) for women and n-3 HUFAs in both genders, assessed with the FFQ compared with FA concentration in plasma, were moderate, but no significant associations were found for saturated fatty acids, monounsaturated fatty acids or n-6 PUFAs. Keywords: fatty acids; food frequency questionnaire; plasma concentration; relative validity