Although small fish are an important source of micronutrients, the relationship between their intake and mortality remains unclear. This study aimed to clarify the association between intake of small fish and all-cause and cause-specific mortality.

We used the data from a cohort study in Japan. The frequency of the intake of small fish was assessed using a validated FFQ. The hazard ratio (HR) and 95 % confidence interval (CI) for all-cause and cause-specific mortality according to the frequency of the intake of small fish by sex were estimated using a Cox proportional hazard model with adjustments for covariates.

The Japan Multi-Institutional Collaborative Cohort Study.

A total of 80 802 participants (34 555 males and 46 247 females), aged 35–69 years.

During a mean follow-up of 9·0 years, we identified 2482 deaths including 1495 cancer-related deaths. The intake of small fish was statistically significantly and inversely associated with the risk of all-cause and cancer mortality in females. The multivariable-adjusted HR (95 % CI) in females for all-cause mortality according to the intake were 0·68 (0·55, 0·85) for intakes 1–3 times/month, 0·72 (0·57, 0·90) for 1–2 times/week and 0·69 (0·54, 0·88) for ≥ 3 times/week, compared with the rare intake. The corresponding HR (95 % CI) in females for cancer mortality were 0·72 (0·54, 0·96), 0·71 (0·53, 0·96) and 0·64 (0·46, 0·89), respectively. No statistically significant association was observed in males.

Intake of small fish may reduce the risk of all-cause and cancer mortality in Japanese females.

To examine the demographic and lifestyle characteristics related to the dietary inflammatory index (DII™) score and to evaluate the association between DII score and disability among older people in Japan.

Cross-sectional design. The DII score was calculated from nutrient intake information obtained from a FFQ. Disability was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence questionnaire. Overall disability and disability in each component of everyday competence, that is, instrumental activities of daily living (IADL), intellectual activities and social participation, were assessed. Those with a deficit in one or more activities were defined as disabled.

Five non-urban areas in Japan.

A total of 1642 Japanese older people aged 65 years or older.

Women, residents of Oga-shi, and those with a higher education and greater frequency of shopping followed a more anti-inflammatory diet, while those living alone and residents of Minamiawaji-shi had higher dietary inflammation. A pro-inflammatory diet was associated with higher odds of overall disability and disability in each component of competence: overall disability, OR (95 % CI) = 1·26 (1·16, 1·36); IADL disability, OR (95 % CI) = 1·16 (1·07, 1·26); disability in intellectual activities, OR (95 % CI): 1·30 (1·20, 1·40); and disability in social participation, OR (95 % CI) = 1·20 (1·11, 1·29).

Sex, living alone, education, frequency of shopping and area of residence were shown to be determinants of DII score in Japanese older people. DII score was positively associated with disability.

Self-reported energy intake (EI) estimation may incur systematic errors that could be attenuated through biomarker calibration. We aimed to confirm whether calibrated EI was comparable to total energy expenditure (TEE) measured using the doubly labelled water (DLW) technique.

Cross-sectional study.

General older population from the Kyoto–Kameoka Study, Japan.

This study included sub- and main cohorts of 72 and 8058 participants aged≥ 65 years, respectively. EI was evaluated using a validated FFQ, and calibrated EI was obtained using a previously developed equation based on the DLW method. TEE was considered representative of true EI and also measured using the DLW method. We used a Wilcoxon signed-rank test and correlation analysis to compare the uncalibrated and calibrated EI with TEE.

In the sub-cohort, the median TEE, uncalibrated EI and calibrated EI were 8559 kJ, 7088 kJ and 9269 kJ, respectively. The uncalibrated EI was significantly lower than the TEE (median difference = –1847 kJ; interquartile range (IQR): –2785 to –1096), although the calibrated EI was not (median difference = 463 kJ; IQR: –330 to 1541). The uncalibrated (r = 0·275) and calibrated EI (r = 0·517) significantly correlated with TEE. The reproducibility was higher for calibrated EI (interclass correlation coefficient (ICC) = 0·982) than for uncalibrated EI (ICC = 0·637). Similar findings were observed when stratifying the sample by sex. For medians, uncalibrated EI was lower (about 17 %) than calibrated EI in the main cohort.

Biomarker calibration may improve the accuracy of self-reported dietary intake estimation.

We aimed to examine missing data in FFQ and to assess the effects on estimating dietary intake by comparing between multiple imputation and zero imputation.

We used data from the Okazaki Japan Multi-Institutional Collaborative Cohort (J-MICC) study. A self-administered questionnaire including an FFQ was implemented at baseline (FFQ1) and 5-year follow-up (FFQ2). Missing values in FFQ2 were replaced by corresponding FFQ1 values, multiple imputation and zero imputation.

A methodological sub-study of the Okazaki J-MICC study.

Of a total of 7585 men and women aged 35–79 years at baseline, we analysed data for 5120 participants who answered all items in FFQ1 and at least 50% of items in FFQ2.

Among 5120 participants, the proportion of missing data was 3·7%. The increasing number of missing food items in FFQ2 varied with personal characteristics. Missing food items not eaten often in FFQ2 were likely to represent zero intake in FFQ1. Most food items showed that the observed proportion of zero intake was likely to be similar to the probability that the missing value is zero intake. Compared with FFQ1 values, multiple imputation had smaller differences of total energy and nutrient estimates, except for alcohol, than zero imputation.

Our results indicate that missing values due to zero intake, namely missing not at random, in FFQ can be predicted reasonably well from observed data. Multiple imputation performed better than zero imputation for most nutrients and may be applied to FFQ data when missing is low.