Ngoc Minh Pham

High levels of stearic acid, palmitoleic acid, and dihomo-γ-linolenic acid and low levels of linoleic acid in serum cholesterol ester are associated with high insulin resistance.

The association of fatty acid composition with insulin resistance and type 2 diabetes has been reported in Western populations, but there is limited evidence of this association among the Japanese, whose populace consume large amounts of fish. To test the hypothesis that high palmitic, palmitoleic, and dihomo-γ-linolenic acids and low levels of linoleic and n-3 fatty acids are associated with higher insulin resistance among the Japanese, the authors investigated the relationship between serum fatty acid composition and serum C-peptide concentrations in 437 Japanese employees aged 21 to 67 years who participated in a workplace health examination. Serum cholesterol ester and phospholipid fatty acid compositions were measured by gas-liquid chromatography. Desaturase activity was estimated by fatty acid product-to-precursor ratios. A multiple regression was used to assess the association between fatty acid and C-peptide concentrations. C-peptide concentrations were associated inversely with linoleic acid levels in cholesterol ester and phospholipid (P for trend = .01 and .02, respectively) and positively with stearic and palmitoleic acids in cholesterol ester (P for trend =.02 and .006, respectively) and dihomo-γ-linolenic acid in cholesterol ester and phospholipid (P for trend < .0001 for both). C-peptide concentrations were not associated with n-3 polyunsaturated fatty acids. C-peptide concentrations significantly increased as δ-9-desaturase (16:1 n-7/16:0) and δ-6-desaturase (18:3 n-6/18:2 n-6) increased (P for trend = .01 and .03, respectively) and δ-5-desaturase (20:4 n-6/20:3 n-6) decreased (P for trend = .004). In conclusion, a fatty acid pattern with high levels of serum stearic, palmitoleic, or dihomo-γ-linolenic acids; δ-9-desaturase (16:1 n-7/16:0) or δ-6-desaturase (18:3 n-6/18:2 n-6) activities; and low levels of serum linoleic acid or δ-5-desaturase (20:4 n-6/20:3 n-6) activity might be associated with higher insulin resistance in Japanese adults.

The relationship of coffee and green tea consumption with high-sensitivity C-reactive protein in Japanese men and women

Abstract Background: Circulating high-sensitivity C-reactive protein (CRP) is a good marker of chronic low-grade inflammation. The few studies that have addressed the relationship between coffee consumption and CRP concentrations report inconsistent findings. The authors of this study examined the relationship between coffee and green tea consumption and serum concentrations of CRP, and the interaction with alcohol consumption, smoking, and obesity in a large population of free-living Japanese men and women. Methods: Study subjects were 10,325 men and women, 49–76 years of age, living in Fukuoka City who participated in a baseline survey of a cohort study on lifestyle-related diseases. Coffee and green tea consumption and other lifestyle characteristics were assessed using a structured questionnaire. Anthropometric measurements and venous blood samples were also included. Results: CRP concentrations were progressively lower with increasing levels of coffee consumption, after adjustment for smoking and other covariates (p for trend=0.03) in men, but not in women. Stratified analysis indicated that this inverse association was primarily limited to men with a high consumption of alcohol (≥50 g/day). Green tea consumption showed no measurable relationship with CRP concentrations in either men or women. Conclusions: Coffee may be protective specifically against alcohol-induced hepatic inflammation. Further studies are warranted in different populations. Clin Chem Lab Med 2010;48:849–54.

The Relation of Coffee Consumption to Serum Uric Acid in Japanese Men and Women Aged 49–76 Years

Objective. Few studies have suggested an inverse relation between coffee intake and serum concentrations of uric acid (UA), but none has addressed the relation in men and women separately. We examined the relation between coffee intake and serum UA levels in free-living middle-aged and elderly men and women in Fukuoka, Japan. Methods. Study subjects were derived from the baseline survey of a cohort study on lifestyle-related diseases, and included 11.662 men and women aged 49–76 years; excluded were those with medication for gout and hyperuricemia, use of diuretic drugs, and medical care for cancer or chronic kidney disease. Statistical adjustment was made for body mass index, alcohol use, hypertension, diabetes mellitus, and other factors. Results. There were inverse associations of coffee consumption with serum UA concentrations and hyperuricemia in men regardless of adjustment for covariates. Women showed a statistically significant, but weaker, inverse association between coffee and serum UA levels after allowance for the confounding factors. Conclusion. The findings add to evidence for a protective association between coffee intake and hyperuricemia.

Dietary patterns and metabolic syndrome in a Japanese working population

BackgroundMetabolic syndrome has become a major public health concern, but the role of diet in the etiology of this syndrome is not well understood. This study investigated the association between major dietary patterns and prevalence of metabolic syndrome in a Japanese working population.MethodsThis cross-sectional study was conducted among 460 municipal employees (284 men and 176 women), aged 21–67 years, who participated in a health survey at the time of periodic checkup. Dietary patterns were derived by using the principal component analysis of the consumption of 52 food and beverage items, which were assessed by a validated brief diet history questionnaire. Metabolic syndrome was defined according to the modified NCEP-ATP III criteria. Logistic regression was used to examine the association between dietary patterns and metabolic syndrome with adjustment of potential confounding variables.ResultsThree dietary patterns were identified. Westernized breakfast pattern characterized by high intakes of bread, confectionaries, and milk and yogurt but low intakes of rice and alcoholic beverages was inversely associated with prevalence of metabolic syndrome and high blood pressure (P for trend = 0.02 and 0.049, respectively). Animal food pattern characterized by high intakes of fish and shellfish, meat, processed meat, mayonnaise, and egg was not associated with prevalence of metabolic syndrome, but was positively associated with high blood glucose (P for trend = 0.03). Healthy Japanese dietary pattern characterized by vegetables and fruits, soy products, mushrooms, and green tea was not appreciably associated with prevalence of metabolic syndrome or its components.ConclusionsThe results suggest that westernized breakfast pattern may confer some protection against metabolic syndrome in Japanese. The causality of these associations needs to be confirmed.

Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population.

OBJECTIVE To examine the association between the consumption of green tea, coffee and caffeine and depressive symptoms. DESIGN Cross-sectional study. Consumption of green tea and coffee was ascertained with a validated dietary questionnaire and the amount of caffeine intake was estimated from these beverages. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale. Multiple logistic regression analysis was performed to compute odds ratios and 95% confidence intervals for depressive symptoms with adjustments for potential confounders. SETTING Two workplaces in north-eastern Kyushu, Japan, in 2009. SUBJECTS A total of 537 men and women aged 20-68 years. RESULTS Higher green tea consumption was associated with a lower prevalence of depressive symptoms. Compared with participants consuming ≤1 cup/d, those consuming ≥4 cups green tea/d had a 51% significantly lower prevalence odds of having depressive symptoms after adjustment for potential confounders, with significant trend association (P for trend = 0·01). Further adjustment for serum folate slightly attenuated the association. Coffee consumption was also inversely associated with depressive symptoms (≥2 cups/d v. <1 cup/d: OR = 0·61; 95% CI 0·38, 0·98). Multiple-adjusted odds for depressive symptoms comparing the highest with the lowest quartile of caffeine consumption was OR = 0·57 (95% CI 0·30, 1·05; P for trend = 0·02). CONCLUSIONS Results suggest that higher consumption of green tea, coffee and caffeine may confer protection against depression.

Meat Consumption and Colorectal Cancer Risk: An Evaluation Based on a Systematic Review of Epidemiologic Evidence Among the Japanese Population

OBJECTIVE The association between meat consumption and colorectal cancer remains inconsistent among Asians. The present study systematically evaluated and meta-analyzed epidemiologic studies on the association between consumption of total and specific meats and colorectal cancer risk among Japanese. METHODS Original data were obtained from MEDLINE searched using PubMed or from searches of the Ichushi database, complemented with manual searches. The associations were evaluated based on the strength of evidence, the magnitude of association and biologic plausibility. A meta-analysis was performed according to total meat, red and processed meat as well as poultry and site-specific cancers. RESULTS Six cohort studies and 13 case-control studies were identified. In cohort studies, most investigations found no association between total meat consumption and colon/rectal cancer, and several studies showed a weak-to-moderate positive association of red meat and processed meat consumption with colon/rectal cancer. The majority of case-control studies showed no association between total meat consumption and colon and rectal cancer; however, several ones reported a weak-to-strong positive association of red and processed consumption with colon and rectal cancer. In meta-analysis, the summary relative risks (95% confidence interval) for the highest versus lowest categories of red meat consumption were 1.16 (1.001-1.34) and 1.21 (1.03-1.43) for colorectal and colon cancer, respectively, and those for processed meat consumption were 1.17 (1.02-1.35) and 1.23 (1.03-1.47) for colorectal and colon cancer, respectively. Poultry consumption was associated with lower risk of rectal cancer; summary relative risk (95% confidence interval) was 0.80 (0.67-0.96). CONCLUSIONS High consumption of red meat and processed meat possibly increases risk of colorectal cancer or colon cancer among the Japanese population.

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.

Serum ferritin is associated with markers of insulin resistance in Japanese men but not in women

OBJECTIVE Several epidemiological studies have reported that high concentrations of circulating ferritin, a marker of iron stores, are related to insulin resistance (IR); however, questions remain regarding inconsistent data between Asian men and women and the inadequate consideration of potential confounding effects on the relationship between ferritin and IR. Our aim was to examine the relationship between serum ferritin concentrations and IR markers in the Japanese population. MATERIALS/METHODS We analyzed data (n=493) from a cross-sectional survey conducted in 2009 among a Japanese working population aged 20-68years. Fasting serum ferritin and insulin levels and fasting plasma glucose levels were determined, and the homeostatic model assessment of IR (HOMA-IR) was calculated. Multiple regression analysis was performed with adjustments for demographic and lifestyle factors, body mass index and serum C-reactive protein. RESULTS Fasting insulin and HOMA-IR significantly increased with increasing levels of serum ferritin after adjustment for covariates in men (P for trend=.005 and .001, respectively). Compared with men in the lowest tertile of serum ferritin, those in the highest tertile had a 24% higher HOMA-IR score. Additional data suggested a positive association between iron intake and HOMA-IR (P for trend=.07) in men. Neither serum ferritin nor iron intake was related to IR markers in women, even in postmenopausal women. CONCLUSIONS Serum ferritin concentrations were positively associated with fasting insulin and HOMA-IR in men but not in women, suggesting an important role of iron storage in the pathogenesis of IR in Japanese men.

Prevalence of diabetes and pre-diabetes among workers: Japan Epidemiology Collaboration on Occupational Health Study.

AIMS Few studies have examined the prevalence of diabetes using glycated hemoglobin (HbA1c), a newly recommended diagnostic test. We examined the prevalence of diabetes and pre-diabetes using both HbA1c and fasting plasma glucose (FPG) and their associations with risk factors for type 2 diabetes in a large-scale Japanese working population. METHODS Participants were 47,172 men and 8280 women aged 20-69 years who received periodic health checkup in nine companies which participated in the Japan Epidemiology Collaboration on Occupational Health study. Participants were categorized into diabetes (HbA1c≥6.5% (≥48mmol/mol), FPG≥126mg/dl (≥7.0mmol/L), or medication for diabetes), pre-diabetes (HbA1c 6.0-6.4% (42-46mmol/mol) or FPG 110-125mg/dl (6.1-6.9mmol/L) among those without diabetes), and normal glucose regulation. RESULTS The prevalence of diabetes was 8.0% and 3.3% in men and women, respectively. Of individuals with diabetes, approximately 80% were defined by HbA1c≥6.5% (≥48mmol/mol) criterion. The prevalence of pre-diabetes was 14.1% in men and 9.2% in women. Prevalence of these glucose abnormalities increased with advancing age, especially during mid-40s and 50s. Higher body mass index and waist circumference, hypertension, dyslipidemia, and current smoking were each associated with higher prevalence of diabetes in both men and women. CONCLUSIONS Using HbA1c and FPG criteria or current medication, one in 13 men and one in 30 women had diabetes in the present Japanese working population. Interventions targeted for those in an early stage of impaired glucose metabolism would be required to prevent diabetes.

Dairy consumption is associated with decreased insulin resistance among the Japanese.

Beneficial effects of dairy consumption in preventing obesity and metabolic syndrome have been suggested, but the association between dairy intake and insulin resistance (IR) is not clear. To test the hypothesis that higher dairy consumption is associated with lower insulin resistance, the authors investigated the association between dairy intake (taking fat content into consideration) and markers of IR in a Japanese working population. A cross-sectional study was conducted in 2009 among 496 subjects aged 20-68 years who participated in a health survey during a periodic checkup. Dairy consumption was assessed using a validated brief dietary history questionnaire. Multiple regression analysis was used to assess the association between fasting serum insulin, plasma glucose, and the homeostatic model assessment of IR (HOMA-IR) and dairy consumption with adjustment for potential confounding variables. The subjects in the highest quartile for total dairy intake showed the lowest mean IR markers compared to those in other categories, although the difference was not statistically significant. Intake of full-fat dairy products was inversely associated with HOMA-IR (P for trend = 0.02). The multivariable adjusted mean HOMA-IR values (with 95% confidence intervals) for the four groups, from those who consumed the fewest to those who consumed the most servings of full-fat dairy products, were 1.04 (0.96-1.12), 1.04 (0.96-1.13), 1.00 (0.91-1.08), and 0.86 (0.76-0.96), respectively. Low-fat dairy intake was not significantly associated with any IR markers. The results suggest that the consumption of full-fat dairy products may be associated with lower IR among Japanese adults.