Nahomi Imaeda

Reproducibility of a short food frequency questionnaire for japanese general population

BACKGROUND In epidemiologic field studies, a food frequency questionnaire (FFQ) is one of the most feasible tools to assess usual dietary habits. The purpose of this study is to evaluate the reproducibility of consumption of foods and nutrients assessed with a self-administered short FFQ in a Japanese general population. METHODS We have investigated 1-year interval reproducibility of a self-administered short FFQ, comprising 47 food items, and 8 frequency categories, among 1,918 subjects (844 males and 1,074 females) who participated in health check-up programs in Central Japan. RESULTS Intakes of energy and 24 nutrients along with 15 food groups estimated using the first questionnaire (FFQ1) were approximately equal to those using the second (FFQ2). Spearman’s rank correlation coefficients (CCs) between intakes of nutrients quantified with FFQ1 and FFQ2 in males were distributed as 0.74 - 0.66- 0.55 (maximum - median - minimum), and intraclass CCs (ICCs) as 0.85 - 0.78 - 0.67. Among females, Spearman’s rank CCs were distributed as 0.73 - 0.62 - 0.54, and ICCs as 0.84 - 0.77 - 0.69. Percentages of exact agreement, exact agreement plus agreement within adjacent categories and disagreement according to quintile categorization were 43%, 80%, and 1%, for males, and 42%, 79%, and 1% for females. Reproducibility figures were higher for the elderly than for young people in both sexes. CONCLUSIONS Our FFQ yielded substantially high reproducibility and it may be applicable for assessing consumption of foods/food groups and energy and selected nutrients for the middle-aged and elderly population in Japan.

Relative validity of a semi-quantitative food frequency questionnaire versus 28-day weighed diet records in Japanese female dietitians

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. Pearsons 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 Spearmans rank CCs with energy-adjustment ranged from 0.28 (confectionery)–0.42 to 0.68 (rice). Respective Pearsons CCs for intakes of nutrients were 0.28 (PUFAs)–0.51 to 0.73 (magnesium), and Spearmans 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).European Journal of Clinical Nutrition (2001) 55, 735–742

Soybean products and reduction of breast cancer risk: a case-control study in Japan.

Components of the Japanese diet, which might contribute to the relatively low breast cancer incidence rates in Japan, have not been clarified in detail. Since soybean products are widely consumed in Japan, a case–control study taking account of the menopausal status was conducted using data from the hospital-based epidemiologic research program at Aichi Cancer Center (HERPACC). In total, 167 breast cancer cases were included and 854 women confirmed as free of cancer were recruited as the control group. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by multiple logistic regression analysis. There were reductions in risk of breast cancer associated with high intake of soybean products among premenopausal women. Compared with women in the lowest tertile, the adjusted ORs for top tertile intake of tofu (soybean curd) was 0.49 (95% CI, 0.25–0.95). A significant decrease in premenopausal breast cancer risk was also observed for increasing consumption of isoflavones (OR=0.44; 95% CI, 0.22–0.89 for highest vs lowest tertile; P for trend=0.02). The present study found a statistically inverse association between tofu or isoflavone intake and risk of breast cancer in Japanese premenopausal women, while no statistically significant association was evident with the risk among postmenopausal women.

Discrepancies in dietary intakes and plasma concentrations of fatty acids according to age among Japanese female dietitians.

Objective: To clarify the influences of age on dietary intakes and plasma concentrations of fatty acids (FAs) in Japanese female dietitians.Subjects and methods: In autumn 1996, we estimated dietary FA intakes based on 7 day weighed diet records and analyzed plasma FA concentrations in 79 healthy Japanese female dietitians, and investigated their relationships with age, dividing into three age groups (young (32–42 y), middle-aged (43–50 y) and elderly (51–66 y)).Results: Dietary intakes of total FA, saturated FAs, monounsaturated FAs, n-3 polyunsaturated FAs (PUFAs) and α-linolenic acid (18:3n-3) were significantly highest in the middle-aged group, and lowest in the elderly. Similar trends were observed for dietary intakes of n-6 PUFAs and linoleic acid (18:2n-6), but there were no differences with regard to eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3) and n-3 highly unsaturated FAs (HUFAs=EPA+22:5n-3+DHA). On the other hand, plasma concentrations of all FAs except for arachidonic acid (20:4n-6) demonstrated positive correlations with age. Moreover, plasma concentrations of EPA in all age groups, DHA in the elderly and n-3 HUFAs in the middle-aged and the elderly were all positively correlated with dietary intakes.Conclusions: We should take into account the influence of age on dietary habit and lipid metabolism when interpreting associations between dietary FA intakes and plasma FA concentrations.Sponsorship: This study was supported in part by a grant-in-aid from the Ministry of Education, Science, Sports, Culture and Technology, Japan (06454242).

Validation study of fatty acid consumption assessed with a short food frequency questionnaire against plasma concentration in middle-aged Japanese people

Objective: To assess the relative validity of data for consumption of fatty acids (FAs) measured with a short food frequency questionnaire (FFQ) in comparison with plasma concentration of FAs. Design: In this cross-sectional study, completed FFQs were secured from 177 (92 male and 85 female) employees working for a company in August 2001. Intake of FAs was assessed with the FFQ, and the values were validated against FA concentration in plasma in overnight-fasting blood. Results: Mean9/SD daily intakes of total fatty acids (TFAs) were 44.49/8.0 g day-1 for men and 42.99/7.2 g day-1 for women. Plasma concentration of TFAs were 12.739/3.78 mmol l-1 for men and 10.549/1.75 mmol l-1 for women. Spearman’s rank correlation coefficients, unadjusted and energy-adjusted by the energy-density method and residual method, for n-3 highly unsaturated fatty acids (HUFAs) were 0.37 (p<0.001), 0.38 (p<0.001) and 0.40 (p<0.001) for men, and 0.41 (p<0.001), 0.26 (p<0 .01) and 0.29 (p<0.01) for women, respectively. Conclusions: Relative validity values of data for intake of n-3 polyunsaturated fatty acids (PUFAs) for women and n-3 HUFAs in both genders, assessed with the FFQ compared with FA concentration in plasma, were moderate, but no significant associations were found for saturated fatty acids, monounsaturated fatty acids or n-6 PUFAs. Keywords: fatty acids; food frequency questionnaire; plasma concentration; relative validity

Seasonal variation in consumption and plasma concentrations of fatty acids in Japanese female dietitians.

Objective: To study seasonal variation in intake and plasma concentrations of fatty acids (FAs) in Japanese female dietitians. Subjects and methods: We assessed consumption of FAs based on four season 7 consecutive day weighed diet records from 71 Japanese female dietitians in 1996–1997. Using overnight fasting venous blood, plasma concentrations of FAs were analyzed by gas chromatography. Seasonal variation in consumption and plasma concentrations was examined by ANOVA for repeated values, followed by Tukeys multiple t-test. We calculated Spearmans partial rank correlation coefficients (CCs) between intake and plasma concentrations of FAs. Furthermore, we computed inter-seasonal Spearmans partial rank CCs for consumption and plasma concentrations of FAs. Results: Statistically significant seasonal differences were observed in consumption for most FAs, except for myristic acid, monounsaturated FAs, oleic acid, n-6 polyunsaturated FAs (PUFAs), linoleic acid, γ-linolenic acid, α-linolenic acid, PUFAs/saturated FAs, and n-6 PUFAs/n-3 PUFAs, and for most plasma concentrations, except for stearic acid, γ-linolenic acid, n-3 PUFAs, α-linolenic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and n-3 highly unsaturated FAs (HUFAs). However, statistically significant Spearmans partial rank CCs between intake and plasma concentrations were observed for EPA, DHA, n-3 HUFAs, n-6 PUFAs/n-3 PUFAs and n-6 PUFAs/n-3 HUFAs for almost all seasons. Conclusions: Seasonal variation exists in consumption and plasma concentrations of FAs, so that this should be taken into account in epidemiological analyses, including case–control and cohort studies.

Changes in blood biochemical markers before, during, and after a 2-day ultramarathon

We studied changes in blood markers of 18 nonprofessional, middle-aged runners of a 2-day, 130 km ultramarathon. Blood was sampled at baseline, after the goals on the first and second day, and at three time points (1, 3, and 5/6 days) after the race. Blood indices showed three patterns. First pattern indices showed essentially no changes after the two goals and after the race, including red blood cell indices, gamma-glutamyl transferase, and tumor necrosis factor-α. Second pattern markers, including the majority of indices, were elevated during the race (and also after the race for some parameters) and then returned to baseline afterward, including hemolysis/red blood cell destruction markers (indirect bilirubin) and an iron reservoir index (ferritin), muscle damage parameters (uric acid, creatine kinase, lactate dehydrogenase, and aspartate aminotransferase), renal function markers (creatinine and blood urea nitrogen), liver injury index (alanine aminotransferase), lipid metabolism indices (free fatty acid), reactive oxygen species and inflammation parameters (white blood cells, interleukin-6, and C-reactive protein), and energy production and catecholamines (adrenaline, noradrenaline, and dopamine). Third pattern index of a lipid metabolism marker – triglyceride – decreased during the race periods and started returning to baseline from then onward. Some hormonal markers such as insulin, leptin, and adiponectin showed unique patterns. These findings appeared informative for nonprofessional athletes to know about an optimal physical activity level, duration, and total exercise for elevating physical performance and monitoring physical/mental conditioning as well as for prevention of overtraining and physical injuries.

Changes of Mental Stress Biomarkers in Ultramarathon

We investigated the possible influence of an exhaustive physical exercise on mental stress biomarkers (serotonin, tryptophan, and beta-endorphin) along with dopamine, noradrenaline and free fatty acids in an ultramarathon race in which 45 km was run on the first day and 90 km on the second. We obtained serum samples at 6 different time points during and after the race from 18 Japanese male runners who completed the marathon. Overall changes of serum serotonin and tryptophan concentrations were statistically significant according to ANOVA for repeated measurements (p < 0.05). Serum serotonin levels elevated rapidly on the first day with the post hoc Tukeys test. Tryptophan concentrations inversely decreased during the race, possibly because of utilization for synthesis of serotonin. Levels of beta-endorphin appeared to increase on the first and second days, but were not statistically significant. In conclusion, serum serotonin, tryptophan and beta-endorphin appeared to be used for mental stress markers in physical exercise.

Folate intake and food sources in Japanese female dietitians

ObjectiveTo assess intake of folate/folic acid and food sources in Japanese female dietitians.Subjects and MethodsWe evaluated folate consumption based on four season 7 consecutive day weighed diet records (WDRs) provided by 80 Japanese female dietitians and compared the results with data from a national survey. We then selected informative foods for folate intake on the basis of 2,240 WDRs according to contribution and multiple regression analyses.ResultsDaily folate consumption (mean±SD) among Japanese dietitians was 413±158 μg from raw foods and 343±128 μg from cooked foods. Average residual rate after cooking was 84±8%. Folate intake in summer was lower than that in other seasons by analysis of variance. According to contribution and multiple regression analyses, the major contributors were vegetables, fruit and green tea.ConclusionsDaily folate intake among Japanese female dietitians was far greater than the 200 μg recommended daily allowance for the Japanese. Irrespective of selection methods and raw/cooked foods, major folate sources were found to be green tea along with vegetables and fruit.

Dietary n-3/long-chain n-3 polyunsaturated fatty acids for prevention of sporadic colorectal tumors: A randomized controlled trial in polypectomized participants

To address preventive effects of n-3 PUFAs/LC n-3 PUFAs on CRTs, a randomized controlled trial was conducted. One-hundred four experimental group participants were advised to increase intake of n-3 PUFAs, including fish/shell fish, fish oil supplements and perilla oils, and to decrease consumption of n-6 PUFAs and fats/oils as a whole for 24 months. One-hundred one control group participants were only cautioned to reduce consumption of fats/oils as a whole. Random allocation was satisfactorily attained, and participants sufficiently complied with our regimen. Intakes, plasma concentrations, and compositions of the RBC and sigmoid colon membranes of n-3 PUFAs, LC n-3 PUFAs, EPA and DHA increased, and the ratios of n-6 PUFAs/n-3 PUFAs and AA/LC n-3 PUFAs decreased without any adverse response. Twenty-four months after the intervention, the multivariate-adjusted hazard ratio (95% confidence intervals) was estimated to be 0.805 (0.536-1.209) with a signal towards the reduced CRT incidence.