Biomarker validation of a long-chain omega-3 polyunsaturated fatty acid food frequency questionnaire.

Long-chain omega-3 PUFA (LC n-3 PUFA) are beneficial for health. To date there is no specific food frequency questionnaire (FFQ) to assess LC n-3 PUFA intakes. The objective of this study is to validate our newly developed FFQ by comparison with LC n-3 PUFA content of both red blood cells (RBC) and plasma, expressed as a percentage of total FA. Fifty-three healthy male and female subjects were recruited from Wollongong, Australia. Average LC n-3 PUFA intakes (mg/d) were estimated using the new FFQ. RBC and plasma FA were assessed using GC. Spearman correlation coefficients were used to assess the linear relationship between FFQ intakes and both RBC and plasma FA. The results show that there were significant Spearman's correlation coefficients between the FFQ intakes and RBC (and plasma) FA for total LC n-3 PUFA, EPA, and DHA (0.50 (0.54), 0.39 (0.54) and 0.40 (0.48), respectively) but not for docosapentaenoic acid. The FFQ was also an effective ranking tool. The FFQ is a valid method based on erythrocyte and plasma FA as biochemical markers. In conclusion, the new FFQ is a valid method that can be used to estimate the LC n-3 PUFA intake of adults.