Validity of a self-administered food frequency questionnaire used in the 5-year follow-up survey of the JPHC Study Cohort I to assess fatty acid intake: comparison with dietary records and serum phospholipid level.

We compared fatty acid intake estimated from our 138-item food frequency questionnaire (FFQ) with 28-day weighed dietary records among a subgroup of JPHC Study Cohort I (102 men and 113 women), and with the corresponding two serum phospholipid levels (88 men). Spearman rank correlation coefficients between fatty acid intakes estimated from FFQ and intakes estimated from DR were as follows: saturated fatty acid, r=0.61 and r=0.60; monounsaturated fatty acid, r=0.50 and r=0.44; for energy adjusted value and Eicosapentaenoic acid (EPA), r=0.62 and r=0.55; docosahexaenoic acid (DHA), r=0.61 and r=0.50; for percentage of total fatty acid intake in men and women, respectively. Spearman rank correlation coefficients between fatty acid intakes estimated from FFQ and the corresponding serum phospholipid levels (% of total fatty acid) were as follows: EPA, r=0.43 and r=0.59; DHA, r=0.35 and r=0.49; for crude value (g/day) and percentage of total fatty acid intake, respectively. In conclusion, relatively high correlations were observed for SFA, MUFA and marine-origin n-3 polyunsaturated fatty acid, whereas we must take into account the indicator of each fatty acid intake when using the data of fatty acid intake assessed with FFQ for JPHC study.