A comparison of methods of assessment of dietary selenium intakes in Otago, New Zealand

The aims of the present study were (1) to compare three methods of assessme nt of dietary Se intake, i.e. chemical analysis of duplicate diets, diet re cords and a food-frequency questionnaire (FFQ) designed specifically for Se , and (2) to determine dietary Se intakes of residents of Otago, New Zealan d. The FFQ was completed by 110 free-living adults. Diet records (3 d) and duplicate diet collections were carried out by forty-three of these subject s chosen on the basis of low blood Se concentration, and during a period wh en consumption of the high-Se foods fish, kidney, liver and Brazil nuts was discouraged. Mean Se intakes were similar for duplicate diet analysis (29 (SD 13) mu g/d) and diet record assessments (28 (SD 15) mu g/d). Estimates of intakes from the FFQ for the subgroup of forty-three subjects were highe r (51 (SD 26) mu g/d) than those from duplicate diets and diet records. Val ues from duplicate diet analysis and diet record assessments were strongly correlated (r 0.7, P = 0.0001), but difference plots indicated a lack of ag reement between the two methods. Thus, diet record assessment was not adequ ate for predicting dietary Se intakes of individuals. Significant correlati ons were found for relationships between Se intake from duplicate diets (mu g/kg body weight per d) and plasma Se, Se intake from diet records (mu g/d and mu g/kg body weight per d) and plasma Se; and Se intake from the FFQ a nd whole-blood Se. Se intakes from duplicate diets and diet records were si milar to those reported previously for New Zealanders, but lower than the r ecommended intakes in the USA (National Research Council, 1989), Australia (Truswell et al. 1990) and the UK (Department of Health, 1991) and the Worl d Health Organization/Food and Agriculture Organization/International Atomi c Energy Agency (1996) normative requirement.