Hiroko Tsuruoka

Coffee and green tea consumption is associated with insulin resistance in Japanese adults.

OBJECTIVE Higher coffee and green tea consumption has been suggested to decrease risk of type 2 diabetes, but their roles in insulin resistance (IR) and insulin secretion remain unclear. This study examined the association between habitual consumption of these beverages and markers of glucose metabolism in a Japanese working population. MATERIALS/METHODS Participants were 1440 Japanese employees (1151 men and 289 women) aged 18-69years. Consumption of coffee and green tea was ascertained via a validated brief diet history questionnaire. Multilevel linear regression was used to estimate means (95% confidence intervals) of fasting insulin, fasting plasma glucose, homeostatic model assessment of IR (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β) and glycated hemoglobin (HbA1c) with adjustment for potential confounding variables. RESULTS Coffee consumption was significantly, inversely associated with HOMA-IR (P for trend=0.03), and the association appeared to be confined to overweight subjects (BMI≥25kg/m(2)) (P for trend=0.01, P for interaction=0.08). Unexpectedly, green tea consumption was positively associated with HOMA-IR (P for trend=0.02), though there was no dose-response relationship among daily consumers of green tea. Neither coffee nor green tea consumption was associated with HOMA-β and HbA1c. CONCLUSIONS Our findings indicate that coffee consumption may be associated with decreased IR, but not with insulin secretion. The positive association between green tea consumption and IR warrants further investigation.

Macronutrient intake and depressive symptoms among Japanese male workers: the Furukawa nutrition and health study

This study was aimed to examine the cross-sectional association of protein, carbohydrate, and fat intake with depressive symptoms among 1794 Japanese male workers aged 18-69 years who participated in a health survey. Dietary intake was assessed with a validated self-administered diet history questionnaire. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Odds ratio of depressive symptoms (CES-D scale of ≥16) was estimated by using multiple logistic regression with adjustment for covariates including folate, vitamin B6, vitamin B12, polyunsaturated fatty acid, magnesium, and iron intake. Multivariable-adjusted odds ratio of depressive symptoms for the highest quartile of protein intake was 26%, albeit not statistically significant, lower compared with the lowest. The inverse association was more evident when a cutoff value of CES-D score ≥19 was used. The multivariable-adjusted odds ratios (95% confidence intervals) for the highest through lowest quartile of protein intake were 1.00 (reference), 0.69 (0.47-1.01), 0.69 (0.44-1.09), and 0.58 (0.31-1.06) (P for trend=0.096). Neither carbohydrate nor fat intake was associated with depressive symptoms. Our findings suggest that low protein intake may be associated with higher prevalence of depressive symptoms in Japanese male workers.

Bedtime and Sleep Duration in Relation to Depressive Symptoms among Japanese Workers

Bedtime and Sleep Duration in Relation to Depressive Symptoms among Japanese Workers: Nobuaki SAKAMOTO, et al. Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine—

Dietary patterns derived by reduced rank regression (RRR) and depressive symptoms in Japanese employees: The Furukawa nutrition and health study

Depression has been linked to the overall diet using both exploratory and pre-defined methods. However, neither of these methods incorporates specific knowledge on nutrient-disease associations. The aim of the present study was to empirically identify dietary patterns using reduced rank regression and to examine their relations to depressive symptoms. Participants were 2006 Japanese employees aged 19-69 years. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Diet was assessed using a validated, self-administered diet history questionnaire. Dietary patterns were extracted by reduced rank regression with 6 depression-related nutrients as response variables. Logistic regression was used to estimate odds ratios of depressive symptoms adjusted for potential confounders. A dietary pattern characterized by a high intake of vegetables, mushrooms, seaweeds, soybean products, green tea, potatoes, fruits, and small fish with bones and a low intake of rice was associated with fewer depressive symptoms. The multivariable-adjusted odds ratios of having depressive symptoms were 0.62 (95% confidence interval, 0.48-0.81) in the highest versus lowest tertiles of dietary score. Results suggest that adherence to a diet rich in vegetables, fruits, and typical Japanese foods, including mushrooms, seaweeds, soybean products, and green tea, is associated with a lower probability of having depressive symptoms.

Low Serum 25-Hydroxyvitamin D Concentrations Are Associated with Increased Likelihood of Having Depressive Symptoms among Japanese Workers

BACKGROUND Accumulating evidence suggests a protective role of vitamin D against mood disorders; however, epidemiologic studies are scarce in working populations. OBJECTIVE We investigated cross-sectionally the association of serum vitamin D status and depressive symptoms among Japanese workers. METHODS Participants were 1786 employees (9% women), aged 19-69 y, who received health check-ups and participated in a nutrition and health survey. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured with the use of a competitive protein binding assay. Depressive symptoms were assessed by using the Center for Epidemiologic Studies Depression (CES-D) scale. Logistic regression was used to estimate ORs with adjustment for potential confounding variables including dietary factors. RESULTS Overall, 92% of study participants had suboptimal vitamin D status [25(OH)D <30 μg/L]. Depressive symptoms were inversely associated with 25(OH)D. Compared with those with a 25(OH)D concentration of <20 μg/L, multivariable-adjusted ORs (95% CIs) for depressive symptoms (CES-D scale score ≥16) were 0.75 (0.59, 0.95) and 0.66 (0.41, 1.06) for those with a 25(OH)D concentration of 20-29 μg/L and ≥30 μg/L, respectively (P-trend = 0.01). After further adjustment for leisure-time physical activity and shift work (factors closely related to photo-initiated vitamin D production), the OR (95% CI) for the highest category of 25(OH)D was 0.70 (0.43, 1.14). The association between 25(OH)D and depressive symptoms appears to be linear, according to restricted cubic spline regression. CONCLUSION Results suggest that lower concentrations of circulating vitamin D are associated with increased likelihood of having depressive symptoms among apparently healthy workers.

Dietary patterns and sleep symptoms in Japanese workers: the Furukawa Nutrition and Health Study

OBJECTIVE Experimental studies have shown that some nutrients are involved in initiating and maintaining sleep, but epidemiological evidence on overall dietary patterns and insomnia is scarce. We investigated the relationship between dietary patterns and sleep symptoms in a Japanese working population. METHODS The participants were 2025 workers, aged 18-70 years, who participated in a health survey during a periodic checkup in 2012 and 2013. Dietary intake was assessed with a self-administered diet history questionnaire. Dietary patterns were extracted by principal component analysis on the basis of the energy-adjusted intake of 52 food and beverage items. Sleep duration, difficulty initiating and maintaining sleep, and poor quality of sleep were self-reported. Logistic regression was used to estimate the odds ratios of each sleep symptom according to quartile categories of each dietary pattern with adjustment for potential confounding variables. RESULTS We identified three major dietary patterns. A healthy pattern, characterized by a high intake of vegetables, mushrooms, potatoes, seaweeds, soy products, and eggs, was associated with a decreased prevalence of difficulty initiating sleep once or more a week (P for trend = 0.03); the multivariate adjusted odds ratio in the highest quartile of this score compared with the lowest was 0.75 (95% CI: 0.57-0.99). This association persisted after the exclusion of individuals with severe depressive symptoms. However, there was no significant association with difficulty initiating sleep at least three times a week. CONCLUSIONS Our findings suggest that a healthy dietary pattern may be associated with difficulty initiating sleep at least once a week.

Plant Oils Were Associated with Low Prevalence of Impaired Glucose Metabolism in Japanese Workers

Fatty acid has been suggested to be involved in development of diabetes. However, its association is unclear among Japanese populations, which consume large amounts of fish rich in n-3 polyunsaturated fatty acids. The present cross-sectional study examined the association of individual dietary fatty acids and dietary fatty acid patterns with abnormal glucose metabolism among 1065 Japanese employees, aged 18–69 years. Impaired glucose metabolism is defined if a person has a history of diabetes, current use of anti-diabetic drug, fasting plasma glucose of 110 mg/dl (≥6.1 mmol/L) or greater, or hemoglobin A1C of 6.0% (≥42 mmol/mol) or greater. Dietary intake was assessed with a self-administered diet history questionnaire. Dietary fatty acid patterns were extracted by principal component analysis. Odds ratios of impaired glucose metabolism according to tertile categories of each fatty acids and dietary fatty acid patterns were estimated using logistic regression with adjustment for potential confounding variables. A higher intake of polyunsaturated fatty acid, n-6 fatty acid, linoleic acid, and oleic acid were significantly associated with a decreased prevalence of impaired glucose metabolism (P for trend = 0.03, 0.01, 0.02, and 0.04, respectively). Alpha-linolenic acid was marginally significantly associated with a decreased prevalence of impaired glucose metabolism (P for trend = 0.12). Of three fatty acid patterns identified, a higher plant oil pattern score, which characterized by high intake of alpha-linolenic acid, linoleic acid, and oleic acid, was associated with a decreased prevalence of impaired glucose metabolism (P for trend = 0.03). No association was observed for other patterns. In conclusion, plant source fatty acids might be protectively associated with development of diabetes in Japanese adults.

Noise Attenuation of Earplugs as Measured by hREAT and F-MIRE Methods in a Japanese Metal Manufacturing Plant

Noise Attenuation of Earplugs as Measured by hREAT and F‐MIRE Methods in a Japanese Metal Manufacturing Plant: Isamu KABE, et al. Furukawa Electric Corporation—

Flushing Response Modifies the Association of Alcohol Consumption with Markers of Glucose Metabolism in Japanese Men and Women

BACKGROUND Influences of alcohol use on glucose metabolism may depend on alcohol flushing response. We investigated the effect of alcohol flushing response on the associations between alcohol consumption and markers of glucose metabolism in Japanese men and women. METHODS The subjects were 979 employees (885 men and 94 women), aged 18 to 69 years, of a manufacturing company in Japan. Flushing response and alcohol consumption were determined using a self-administered questionnaire. Homeostasis model assessment-insulin resistance (HOMA-IR) and homeostasis model assessment for β-cell function (HOMA-β) were computed using fasting plasma glucose and insulin. For each group of flushers and nonflushers, multiple regression analysis was used to estimate means of fasting plasma glucose, hemoglobin A1c (HbA1c), and HOMAs for each category of alcohol consumption, with adjustments for potential confounders. RESULTS In flushers, alcohol consumption was associated with HbA1c levels in a U-shaped manner, with the lowest HbA1c levels being observed at an alcohol consumption level of 23.0 to <34.5 g ethanol/d (p for quadratic trend = 0.002). In nonflushers, alcohol consumption was linearly and inversely associated with HbA1c levels (p for linear trend = 0.001). Decreases in HbA1c were more evident among flushers compared with nonflushers at moderate alcohol consumption levels (p for interaction = 0.049). An increase of fasting glucose associated with highest alcohol consumption was observed in both flushers and nonflushers. A statistically significant decrease in HOMA-IR with increasing alcohol consumption was observed in flushers (p for trend = 0.007), whereas HOMA-IR levels slightly decreased at higher alcohol consumption in nonflushers. HOMA-β similarly decreased with increasing alcohol consumption in both flushers and nonflushers (both p for trend < 0.001). CONCLUSIONS The results suggest that the alcohol flushing response may improve glucose metabolism and insulin resistance at moderate alcohol use levels in apparently healthy Japanese adults.