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.