To investigate the association between suicide death and serum cholesterol levels as measured at times close to suicide death.

We conducted a nested case-control study of 41 cases of suicide deaths and 205 matched controls with serum total cholesterol (TC) levels till 3 years before suicide death in a large cohort of Japanese workers.

Individuals in the lowest versus highest tertile/predefined category of TC in a Japanese working population had a three- to four-fold greater risk of suicide death. Each 10 mg/dl decrement of average TC was associated with an 18% increased chance of suicide death (95% confidence interval, 2–35%). Similar results were found for TC levels at each year.

These results suggest that a low serum TC level in recent past is associated with an increased risk of suicide death.

To compare the relative validity of food group intakes derived from a comprehensive self-administered diet history questionnaire (DHQ) and a brief-type DHQ (BDHQ) developed for the assessment of Japanese diets during the previous month using semi-weighed dietary records (DR) as a reference method.

Between November 2002 and September 2003, a 4 d DR (covering four non-consecutive days), a DHQ (150-item semi-quantitative questionnaire) and a BDHQ (fifty-eight-item fixed-portion-type questionnaire) were completed four times (once per season) at 3-month intervals.

Three areas in Japan: Osaka, Nagano and Tottori.

Ninety-two Japanese women aged 31–69 years and ninety-two Japanese men aged 32–76 years.

Median food group intakes were estimated well for approximately half of the food groups. No statistically significant differences were noted between a 16 d DR and the first DHQ (DHQ1) or between the DR and the first BDHQ (BDHQ1) in fifteen (44 %) and fifteen (52 %) food items for women and in fourteen (41 %) and sixteen (55 %) food items for men, respectively, indicating that both questionnaires estimated median values reasonably well. Median Spearman's correlation coefficients with the DR were 0·43 (range: −0·09 to 0·77) for DHQ1 and 0·44 (range: 0·14 to 0·82) for BDHQ1 in women, with respective values of 0·44 (range: 0·08 to 0·87) and 0·48 (range: 0·22 to 0·83) in men, indicating reasonable ranking ability. Similar results were observed for mean values of the four DHQ and BDHQ.

In terms of food intake estimates, both the DHQ and the BDHQ showed reasonable validity.

Although dietary pattern approaches derived from dietary assessment questionnaires are widely used, only a few studies in Western countries have reported the validity of this approach. We examined the relative validity of dietary patterns derived from a self-administered diet history questionnaire (DHQ) among Japanese adults.

The DHQ, assessing diet during the preceding month, and 4 d dietary records (DR) were collected in each season over one year. To derive dietary patterns, 145 food items in the DHQ and 1259 in the DR were classified into thirty-three predefined food groups, and entered into a factor analysis.

Three areas in Japan; Osaka (urban), Nagano (rural inland) and Tottori (rural coastal).

A total of ninety-two Japanese women and ninety-two Japanese men aged 31–76 years.

We identified three dietary patterns (‘healthy’, ‘Western’ and ‘Japanese traditional’) in women and two (‘healthy’ and ‘Western’) in men, which showed a relatively similar direction and magnitude of factor loadings of food groups across the first and mean of four DHQ (DHQ1 and mDHQ, respectively) and 16 d DR. The Pearson correlation coefficients between DHQ1 and 16 d DR for the healthy, Western and Japanese traditional patterns in women were 0·57, 0·36 and 0·44, and for the healthy and Western patterns in men were 0·62 and 0·56, respectively. When mDHQ was examined, the correlation coefficients improved for women (0·45–0·69).

Dietary patterns derived from the DHQ could be used for epidemiological studies as surrogates of those derived from DR.

Previous studies in Western populations have linked caffeine intake with health status. While detailed dietary assessment studies in these populations have shown that the main contributors to caffeine intake are coffee and tea, the wide consumption of Japanese and Chinese teas in Japan suggests that sources of intake in Japan may differ from those in Western populations. Among these teas, moreover, caffeine content varies widely among the different forms consumed (brewed, canned or bottled), suggesting the need for detailed dietary assessment in estimating intake in Japanese populations. Here, because a caffeine composition database or data obtained from detailed dietary assessment have not been available, we developed a database for caffeine content in Japanese foods and beverages, and then used it to estimate intake in a Japanese population.

The caffeine food composition database was developed using analytic values from the literature, 16 d weighed diet records were collected, and caffeine intake was estimated from the 16 d weighed diet records.

Four areas in Japan, Osaka (Osaka City), Okinawa (Ginowan City), Nagano (Matsumoto City) and Tottori (Kurayoshi City), between November 2002 and September 2003.

Two hundred and thirty Japanese adults aged 30–69 years.

Mean caffeine intake was 256·2 mg/d for women and 268·3 mg/d for men. The major contributors to intake were Japanese and Chinese teas and coffee (47 % each). Caffeine intake above 400 mg/d, suggested in reviews to possibly have negative health effects, was seen in 11 % of women and 15 % of men.

In this Japanese population, caffeine intake was comparable to the estimated values reported in Western populations.

To examine relationships between the ratio of energy intake to basal metabolic rate (EI/BMR) and age and body mass index (BMI) among Japanese adults.

Energy intake was assessed by 4-day semi-weighed diet records in each of four seasons (16 days in total). The EI/BMR ratio was calculated from reported energy intake and estimated basal metabolic rate as an indicator of reporting accuracy.

Residents in three areas in Japan, namely Osaka (urban), Nagano (rural inland) and Tottori (rural coastal).

One hundred and eighty-three healthy Japanese men and women aged ≥30 years.

The oldest age group (≥60 years) had higher EI/BMR values than the youngest age group (30–39 years) in both sexes (1.74 vs. 1.37 for men; 1.65 vs. 1.43 for women). In multiple regression analyses, age correlated positively (partial correlation coefficient, β = 0.012, P < 0.001 for men; β = 0.011, P < 0.001 for women) and BMI correlated negatively (β = −0.031, P < 0.001 for men; β = −0.025, P < 0.01 for women) with EI/BMR.

Age and BMI may influence the relative accuracy of energy intake among Japanese adults.