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Green tea

January 2007

Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study.

CONTEXT: Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear. OBJECTIVE: To investigate the associations between green tea consumption and all-cause and cause-specific mortality. DESIGN, SETTING, AND PARTICIPANTS: The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40,530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality. MAIN OUTCOME MEASURES: Mortality due to cardiovascular disease, cancer, and all causes. RESULTS: Over 11 years of follow-up (follow-up rate, 86.1%), 4,209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1,134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category. CONCLUSION: Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.

JAMA. 2006 Sep 13;296(10):1255-65

Circulating oxidized low-density lipoprotein is an independent predictor for cardiac event in patients with coronary artery disease.

Oxidized low-density lipoprotein (oxLDL) plays a crucial role in the development of atherosclerosis, however, the predictive value of circulating oxLDL for cardiac events (CE) in patients with coronary artery disease (CAD) has remained poorly understood. We prospectively studied 238 consecutive patients with documented CAD for up to 52 months until the occurrence of one of the following cardiac events: cardiac death, nonfatal myocardial infarction (MI), and refractory angina requiring revascularization. The plasma levels of oxLDL were measured by an enzyme-linked immunosorbent assay (ELISA) using the monoclonal antibody, DLH3. The levels of circulating oxLDL were significantly higher in patients with CE than in patients without CE (median 20.3 U/ml versus 17.6 U/ml, P = 0.002). Multivariate Cox models showed that higher level of oxLDL was an independent predictor of developing CE. The adjusted hazard ratios for CE were 3.15 (95% CI 1.47-6.76, P = 0.003) times higher in patients with the highest quartile of oxLDL levels and 1.88 (95% CI 0.90-3.95, P = 0.09) times higher in patients with the third quartile than in those within the lowest quartile. Thus, measurement of circulating oxLDL may be helpful in the assessment of future CE in patients with CAD.

Atherosclerosis. 2004 Jun;174(2):343-7

The metabolic syndrome, circulating oxidized LDL, and risk of myocardial infarction in well-functioning elderly people in the health, aging, and body composition cohort.

The object of this study was to establish the association between the metabolic syndrome and oxidized LDL (oxLDL) and to determine the risk for coronary heart disease (CHD) in relation to the metabolic syndrome and levels of oxLDL. OxLDL was measured in plasma from 3,033 elderly participants in the Health, Aging, and Body Composition study. The metabolic syndrome was defined according to criteria established in the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. We observed that the metabolic syndrome was associated with higher levels of oxLDL due to a higher fraction of oxLDL, not to higher levels of LDL cholesterol. Individuals with the metabolic syndrome had twice the odds of having high oxLDL (>1.90 mg/dl) compared with those not having the metabolic syndrome, after adjusting for age, sex, ethnicity, smoking status, and LDL cholesterol. Among those participants who had the metabolic syndrome at study entry, incidence rates of future CHD events were 1.6-fold higher, after adjusting for age, sex, ethnicity, and smoking status. OxLDL was not an independent predictor of total CHD risk. However, those with high oxLDL showed a greater disposition to myocardial infarction (relative risk 2.25, 95% confidence interval 1.22-4.15). We concluded that the metabolic syndrome, a risk factor for CHD, is associated with higher levels of circulating oxLDL that are associated with a greater disposition to atherothrombotic coronary disease.

Diabetes. 2004 Apr;53(4):1068-73

Associations among oxidized low-density lipoprotein antibody, C-reactive protein, interleukin-6, and circulating cell adhesion molecules in patients with unstable angina pectoris.

Oxidized low-density lipoprotein (LDL) is believed to play a key role in the development of atherosclerosis. However, the significance of anti-oxidized LDL antibody in atherogenesis is unclear. The purposes of this study were to assess whether anti-oxidized LDL antibody titers are related to other inflammatory markers of possible interest in atherosclerotic development, such as soluble cell adhesion molecules, interleukin-6, and C-reactive protein (CRP), and to determine the prognostic value of anti-oxidized LDL antibody as a predictor of cardiac events in patients with unstable angina pectoris. Sixty patients (35 men and 25 women; mean age 60 years) with unstable angina were included in this study. The levels of CRP and of intercellular adhesion molecule-1 (ICAM-1) at 24 and 72 hours after admission were significantly higher than their baseline levels (p <0.05, respectively). After adjusting for age, gender, body mass index, and statin use, anti-oxidized LDL antibodies were positively correlated with CRP (r = 0.72, p <0.001) and ICAM-1 (r = 0.68, p <0.001). Elevated anti-oxidized LDL antibodies (mean >11.37 U/ml) and CRP levels (median >2.4 mg/L) on admission were correlated with a significantly lower 16-month, event-free survival rate (Kaplan-Meier event-free survival analysis, log-rank p <0.01 and p <0.05, respectively). Multivariate analysis by logistic regression revealed that elevated levels of anti-oxidized LDL antibody (mean >11.3 U/ml) on admission were an independent risk factor for an adverse cardiac event (odds ratio 2.2, 95% confidence interval 1.5 to 10.7, p = 0.001). This study demonstrates that anti-oxidized LDL antibody expression is associated with the expression of CRP and adhesion molecules, especially ICAM-1, and is a predictor of cardiac events in patients with unstable angina pectoris. The observed elevated levels of anti-oxidized LDL antibody suggest plaque instability and may be useful for identifying patients at higher risk of a cardiac event.

Am J Cardiol. 2004 Mar 1;93(5):554-8

Relation between antibody against oxidized low-density lipoprotein and extent of coronary atherosclerosis.

BACKGROUND AND PURPOSE: The role of antibody against oxidized low-density lipoprotein (Ab-ox-LDL) in acute myocardial infarction (AMI) and coronary artery disease (CAD) has not been fully elucidated. This study investigated the relationship between Ab-ox-LDL titers and the extent of coronary atherosclerosis, and determined the clinical significance of this antibody in AMI. METHODS: A total of 70 patients with significant coronary atherosclerosis demonstrated by coronary angiography were recruited. These patients were divided into AMI (n = 33; mean age, 63 yr; 29 men) and chronic stable CAD (n = 37; mean age, 62 yr; 30 men) groups. Serum Ab-ox-LDL was measured using an enzyme-linked immunosorbent assay. The extent of coronary atherosclerosis was assessed by an angiographic diffuse score system. RESULTS: In all patients, Ab-ox-LDL was significantly correlated with white blood cell count (r = 0.309; p = 0.009), but not with lipid profile or the diffuse score. Ab-ox-LDL (422.0 +/- 60.4 vs. 263.8 +/- 30.2 U/L; p = 0.018), white blood cell count (9,742 +/- 457 vs. 7,211 +/- 327/mm3; p < 0.001), and C-reactive protein (10.5 +/- 3.1 vs. 2.9 +/- 0.5 mg/L; p = 0.022) were significantly higher in patients with AMI than in those with chronic CAD. Peak creatine kinase concentration was significantly correlated with Ab-ox-LDL (r = 0.499; p = 0.003) among patients with AMI. CONCLUSION: Ab-ox-LDL is higher in patients with AMI and is correlated with myocardial damage to a greater degree than with the severity of coronary atherosclerosis and lipid profiles.

J Formos Med Assoc. 2002 Oct;101(10):681-4

The autoantibody expression against different source of oxidized low density lipoprotein in patients with acute myocardial infarction.

The aim of this study was to examine the expression of antibodies against two different sources of low density lipoprotein (LDL) that were oxidized by CuSO(4), in patients with early stage of acute myocardial infarction (AMI). When LDL purified from sera with high level of LDL was used as a modified antigen, the results indicated that the titers of antibodies against the oxidized LDL in 30 patients were increased by 135% compared to those in normal subjects; however, the titers of antibody against modified LDL purified from normal-range LDL in the same patients were only slightly increased by 52%. Comparing the levels of autoantibody expressed in the high LDL sera group, high triglyceride sera group, and AMI patients sera group (total of 41; in addition to 30 AMI patients, 11 more sera of AMI patients were collected), the amount of autoantibody against the oxLDL purified from high LDL sera in AMI patients sera group was significantly increased up to 195%. In contrast to AMI patients, the sera titers against the same antigen in two subject groups with either high LDL or high triglyceride are only 50% higher than normal subjects. Moreover, the ratio of thromboxane B(2) over 6-keto-prostaglandin F(1alpha) (6-keto-PG F(1alpha)) in the acute myocardial infarction patients was 1.79, which is much lower than the normal subjects, 4.19. Concluding from the above observations, we suggest that the expression level of anti-oxidized LDL antibody may play a role on the pathogenesis of acute myocardial infarction disease, but is independent with the levels of thromboxane A(2) and prostacyclin in the examined sera.

Thromb Res. 2002 Aug 15;107(3-4):175-9