Effect of seasonality on the estimated mean value of nutrients and ranking ability of a self administered diet history questionnaire
Effect of seasonality on the estimated mean value of nutrients and ranking ability of a self administered diet history questionnaire
Year: 2014
Authors: Suga, H. Asakura, K. Sasaki, S. Nojima, M. Okubo, H. Hirota, N. Notsu, A. Fukui, M.
Publication Name: Nutr J.
Publication Details: Volume 13; Issue 51; Pages 2 – 10
Abstract:
Background We examined the effect of seasonality on the validity (ability to estimate the mean intake of a group and ranking ability) of nutrient intakes estimated with a comprehensive self administered diet history questionnaire (DHQ) developed for the assessment of Japanese diets during the preceding one month, using semi weighed
dietary records (DRs) as a reference method. Methods This study was conducted in three areas in Japan (Osaka, Nagano, and Tottori). The study population included 92 Japanese men aged 32 to 76 years and 92 Japanese women aged 31 to 69 years (30 from Osaka, 31 from Nagano, and 31 from Tottori for each sex). A DHQ and a four day DR were completed four times at 3 month intervals, once per season. The effect of seasonality was examined by the level of agreement among seasons using mean nutrient intake and correlation coefficients. Results Significant differences in estimated energy adjusted intakes of 42 selected nutrients between the average of DRs administered 16 times throughout a year and that of the DHQ administered four times in each season (fall, winter, spring, and summer) were observed for 30, 29, 30, and 31 nutrients for men and 21, 28, 30, and 31 nutrients for women, respectively. Pearson correlation coefficients between the DRs and the DHQs for energy adjusted intakes of the 42 nutrients showed significant inter season differences in 11 nutrients for men and 13 nutrients for women. Particularly, correlation coefficients of fat, monounsaturated fat, polyunsaturated fat, n 6 polyunsaturated fat, alpha linolenic acid, and cholesterol in spring and cryptoxanthin in summer for men, and fat, saturated fat, and monounsaturated fat in spring and summer and thiamin and iron in summer for women were markedly altered by seasonality. Conclusions Mean nutrient intake estimated by the DHQ varied by season, indicating that any consideration of nutrient intake estimated by the DHQ as a yearly average intake may be problematic. In contrast, the effect of seasonality on the ranking ability of the DHQ was relatively small, and thus the use of a DHQ to rank individuals by nutrient intake is acceptable for epidemiological studies, regardless of season. (Authors abstract)
dietary records (DRs) as a reference method. Methods This study was conducted in three areas in Japan (Osaka, Nagano, and Tottori). The study population included 92 Japanese men aged 32 to 76 years and 92 Japanese women aged 31 to 69 years (30 from Osaka, 31 from Nagano, and 31 from Tottori for each sex). A DHQ and a four day DR were completed four times at 3 month intervals, once per season. The effect of seasonality was examined by the level of agreement among seasons using mean nutrient intake and correlation coefficients. Results Significant differences in estimated energy adjusted intakes of 42 selected nutrients between the average of DRs administered 16 times throughout a year and that of the DHQ administered four times in each season (fall, winter, spring, and summer) were observed for 30, 29, 30, and 31 nutrients for men and 21, 28, 30, and 31 nutrients for women, respectively. Pearson correlation coefficients between the DRs and the DHQs for energy adjusted intakes of the 42 nutrients showed significant inter season differences in 11 nutrients for men and 13 nutrients for women. Particularly, correlation coefficients of fat, monounsaturated fat, polyunsaturated fat, n 6 polyunsaturated fat, alpha linolenic acid, and cholesterol in spring and cryptoxanthin in summer for men, and fat, saturated fat, and monounsaturated fat in spring and summer and thiamin and iron in summer for women were markedly altered by seasonality. Conclusions Mean nutrient intake estimated by the DHQ varied by season, indicating that any consideration of nutrient intake estimated by the DHQ as a yearly average intake may be problematic. In contrast, the effect of seasonality on the ranking ability of the DHQ was relatively small, and thus the use of a DHQ to rank individuals by nutrient intake is acceptable for epidemiological studies, regardless of season. (Authors abstract)
Epidemiologic studies in the nutritional field strongly depend on the validity of the methods used to estimate the habitual nutrient intake and food consumption of
participants. Dietary questionnaires place a low burden on the respondent, take relatively little time to complete, and are cost effective in large populations, and are often
used to estimate dietary intake. As food and nutrient intake vary by season, many questionnaires attempt to avoid the effects of seasonality by asking about the intake of food during the previous year. The influence of seasonality on the validity of a dietary questionnaire can be addressed from several aspects. The most common methods are comparison of the means and standard deviations, which assess absolute levels of nutrient intake, and the correlation coefficients, which assess the ability to rank subjects according to their nutrient intake. Sasaki et al. have developed a comprehensive self administered diet history questionnaire (DHQ) for the assessment of Japanese diets. The DHQ is a self administered, semi quantitative questionnaire that asks about the consumption frequency and portion size of selected foods to estimate dietary intake during the preceding month. In this study, the effect of seasonality on the validity of the DHQ from the perspective of absolute level and ranking ability was assessed. Also DHQ was used to evaluate whether there are seasons which are unsuitable for estimating habitual nutrient intake, using a 16 day dietary record (DR) as reference. Mean nutrient intake estimated by the DHQ varied according to season, indicating that any consideration of nutrient intake estimated by the DHQ as a yearly average intake may be problematic. The DHQ is a questionnaire which assesses the previous month’s dietary intake, and seasonal variance in mean values estimated by it may therefore represent the true seasonal variance of nutrient intake. On the other hand, the correlation coefficients between the DR and each of the questionnaires showed significant differences for some nutrients, suggesting that seasonality affected the ranking ability of the DHQ for a limited number of nutrients. In this study, the mean intake for energy and most of the 42 nutrients estimated by the DHQ differed significantly from those estimated by the DR, and varied according to season. Kobayashi et al. reported significant differences between mean intakes estimated by the DHQ and by the DR for energy and many energy adjusted nutrients. A significant difference in correlation coefficients between fall and the other seasons in 11 nutrients for men and 13 for women was found. This implies that seasonality can affect the ability to rank individuals according to their intake of these nutrients. There was no significant seasonal difference in the number of food and beverage items appeared in the DR and the DHQ. These results imply the need for caution in administering epidemiological studies which extend over two or more seasons. This study showed that the DHQ has acceptable ranking ability over timescales of 1 year, although the ability to estimate mean values is reasonable for only a limited number of nutrients regardless of the season of dietary questionnaire administration. The findings suggest that values for energy and most nutrients estimated on single administration of the DHQ are acceptable for large scale epidemiological studies in Japan. (Editors comments)
participants. Dietary questionnaires place a low burden on the respondent, take relatively little time to complete, and are cost effective in large populations, and are often
used to estimate dietary intake. As food and nutrient intake vary by season, many questionnaires attempt to avoid the effects of seasonality by asking about the intake of food during the previous year. The influence of seasonality on the validity of a dietary questionnaire can be addressed from several aspects. The most common methods are comparison of the means and standard deviations, which assess absolute levels of nutrient intake, and the correlation coefficients, which assess the ability to rank subjects according to their nutrient intake. Sasaki et al. have developed a comprehensive self administered diet history questionnaire (DHQ) for the assessment of Japanese diets. The DHQ is a self administered, semi quantitative questionnaire that asks about the consumption frequency and portion size of selected foods to estimate dietary intake during the preceding month. In this study, the effect of seasonality on the validity of the DHQ from the perspective of absolute level and ranking ability was assessed. Also DHQ was used to evaluate whether there are seasons which are unsuitable for estimating habitual nutrient intake, using a 16 day dietary record (DR) as reference. Mean nutrient intake estimated by the DHQ varied according to season, indicating that any consideration of nutrient intake estimated by the DHQ as a yearly average intake may be problematic. The DHQ is a questionnaire which assesses the previous month’s dietary intake, and seasonal variance in mean values estimated by it may therefore represent the true seasonal variance of nutrient intake. On the other hand, the correlation coefficients between the DR and each of the questionnaires showed significant differences for some nutrients, suggesting that seasonality affected the ranking ability of the DHQ for a limited number of nutrients. In this study, the mean intake for energy and most of the 42 nutrients estimated by the DHQ differed significantly from those estimated by the DR, and varied according to season. Kobayashi et al. reported significant differences between mean intakes estimated by the DHQ and by the DR for energy and many energy adjusted nutrients. A significant difference in correlation coefficients between fall and the other seasons in 11 nutrients for men and 13 for women was found. This implies that seasonality can affect the ability to rank individuals according to their intake of these nutrients. There was no significant seasonal difference in the number of food and beverage items appeared in the DR and the DHQ. These results imply the need for caution in administering epidemiological studies which extend over two or more seasons. This study showed that the DHQ has acceptable ranking ability over timescales of 1 year, although the ability to estimate mean values is reasonable for only a limited number of nutrients regardless of the season of dietary questionnaire administration. The findings suggest that values for energy and most nutrients estimated on single administration of the DHQ are acceptable for large scale epidemiological studies in Japan. (Editors comments)
