Evaluation of relative intake of fatty acids according to the Northern Sweden FFQ with fatty acid levels in erythrocyte membranes as biomarkers.

OBJECTIVE To evaluate the validity of the Northern Sweden eighty-four-item FFQ to estimate intake of fatty acids relative to 24 h diet recalls (24-HDR) and fatty acids in erythrocyte membranes. DESIGN Participants, randomly recruited from the population-based Västerbotten Intervention Project, answered the eighty-four-item FFQ. During the following year each participant carried out ten 24-HDR. Intake of fatty acids measured by the FFQ was compared with intake by the 24-HDR and fatty acid levels in erythrocytes. SETTING The county of Västerbotten in northern Sweden. SUBJECTS Ninety-six men and ninety-nine women. RESULTS Spearman correlation coefficients (rs) between intakes of the fatty acids 14 : 0, 15 : 0, 16 : 0, 17 : 0, 18 : 2n-6, 18 : 3n-3, 20 : 5n-3 and 22 : 6n-3 estimated by the FFQ and the 24-HDR were all significant and ranged from 0.29 (22 : 6n-3 in men and women) to 0.60 (16 : 0 in men), whereas significant correlations between FFQ-estimated intake and erythrocyte membrane content were only seen for milk fatty acids 14 : 0, 15 : 0 and 17 : 0 (rs = 0.23-0.34) and fish fatty acids 20 : 5n-3 and 22 : 6n-3 (rs = 0.42-0.51). CONCLUSION The Northern Sweden eighty-four-item FFQ gives a satisfactory estimate of the intake of fish fatty acids (20 : 5n-3 and 22 : 6n-3) and milk fatty acids (15 : 0 and 17 : 0), whereas its validity for fatty acids 18 : 2n-6 and 18 : 3n-3, derived mainly from vegetable oils, cannot be shown.