A cross-sectional study was conducted to clarify the associations of lifestyle factors (habitual exercise, alcohol intake and smoking habit) and plasma fatty acid (FA) concentrations as biomarkers of dietary FA intakes. We collected 7-d weighed diet records, lifestyle information and blood samples from 15 male and 79 female Japanese dietitians, and estimated dietary FA intakes and analyzed plasma FA concentrations. Plasma concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and (n-3) highly unsaturated FA (HUFA) derived from marine foods, but not linoleic and alpha-linolenic acid from plant origins, demonstrated positive correlations with dietary intakes (r = 0.303-0.602, P < 0.05) in both genders. Multiple linear regression analyses adjusted for age, BMI, total energy intake, fat (or respective FA) consumption and lifestyle factors showed that dietary intakes of EPA, DHA and (n-3) HUFA were positively associated with age in men (P < 0.05) and negatively associated with BMI in women [P < 0.01 for DHA and (n-3) HUFA]. The plasma concentrations of EPA, DHA and (n-3) HUFA in women were found to be positively associated with age and marine oil (or respective FA) intake (P < 0.01), and negatively associated with total energy intake [P < 0.05 for EPA and (n-3) HUFA]. Lifestyle factors were not associated with dietary FA intakes and plasma FA concentrations. These findings suggest that the plasma concentrations of EPA, DHA and (n-3) HUFA might be useful biomarkers for the assessment of relative FA intakes without considering associations with habitual exercise, alcohol intake and smoking habit.

The relative contributions of variability by person were largest for all nutrients, followed by those due to sequence of days, season and day of week. Within-individual variation was greater than between-individual variation. Minimal days necessary for ascertaining major nutrients were in general fewer than micro-nutrients.

Objective: To assess the relative validity of a semi-quantitative food frequency questionnaire (SQFFQ) against 28 day weighed diet records (WDRs). Subjects and methods: The SQFFQ was administered to 106 (21 male and 85 female) Japanese dietitians in Aichi Prefecture in autumn, 1996 and four-season consecutive 7 day WDRs were carried out during 1996 -1997. We evaluated validity of intakes of 15 foods and 31 macro-and micro-nutrients based on the SQFFQ against those according to 28 day WDRs among 79 Japanese female dietitians. Results: Mean daily intakes of selected foods and nutrients determined by the SQFFQ were generally equivalent to those measured by 28 day WDRs. Pearson's de-attenuated correlation coefficients (CCs) with log-transformation and energy-adjustment between intakes of selected foods and nutrients quantified by the SQFFQ and 28 day WDRs (minimum -median -maximum) ranged from 0.17 (beverages) -0.52 to 0.74 (rice), and Spearman's rank CCs with energy-adjustment ranged from 0.28 (confectionery) -0.42 to 0.68 (rice). Respective Pearson's CCs for intakes of nutrients were 0.28 (PUFAs) -0.51 to 0.73 (magnesium), and Spearman's rank CCs ranged from 0.23 (n-3 PUFAs) -0.45 to 0.71 (magnesium). Favorably higher agreement for intakes of foods=nutrients was achieved along with lower disagreement. Conclusions: Satisfactorily higher relative validity was attained in Japanese female dietitians with the SQFFQ. This calibrated questionnaire seems therefore appropriate for administration to Japanese dietitians to clarify associations between diet and health=disease. Sponsorship: A grant-in-aid from the Ministry of Education, Science, Sports and Culture (06454242). Descriptors: Japanese female dietitians; relative validity=calibration; semi-quantitative food frequency questionnaire; weighed diet records

Background:We designed a data-based semi-quantitative food frequency questionnaire to clarify the relationship between food intake and lifestyle-related diseases among middle-aged Japanese. Methods: A total of 351 middle-aged individuals were recruited to a one-day weighed diet record survey in 1994. In all, 586 foods were consumed. Intakeof 31 nutrients including energy, protein, fat, carbohydrate, vitamins, minerals and dietary fiber by food was computed by multiplying the weight of food consumed by its nutrient content. First, 252 foods with up to 90 cumulative 0/0 contribution to nutrientintakewere selected. Of these, foods having apparently the same/similar nutrient content were combined into 206 foods by research dietitians. Next, 183 foods with up to 0.90 cumulative multiple regression coefficient and 90 cumulative % contribution were chosen. At this stage an additional food grouping was made. Results: Finally, 102 foods/recipes were included in the questionnaire: rice (2 items), bread and noodles (11), eggs, milkand dairyproducts (10), soybean, soybean products andotherbeans (7), meat including beef, pork and chicken (12), fish (5), other fish, shellfish and fish products (10), green-yellow vegetables (8), other vegetables and mushrooms (7), edible roots (2), seaweeds (3), seeds (2), fruits (8), beverages (7) and confectioneries (8). The frequencies were classified intoeight categories. Portion size was calculated for the respective foodslargelyfrom the one-day weighed diet record. Conclusions:The developed semi-quantitative food frequency questionnaire substantially coveredthe intakeof 31 nutrients andmaybecompetentto rankmiddle-aged Japanese efficiently.