Oolong tea increases plasma adiponectin levels and low-density lipoprotein particle size in patients with coronary artery disease

doi:10.1016/j.diabres.2004.01.003

Diabetes Research and Clinical Practice

Volume 65, Issue 3, September 2004, Pages 227-234

https://doi.org/10.1016/j.diabres.2004.01.003 Get rights and content

Abstract

Background: Oolong tea has been studied for its effect on cardiovascular disease and obesity. Plasma adiponectin levels are reduced in obesity, in patients with type 2 diabetes mellitus and in coronary artery disease (CAD). Objective: To investigate prospectively, whether intake of Oolong tea influences plasma adiponectin levels, low-density lipoprotein (LDL) particle size, total cholesterol, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, serum triglyceride and plasma glucose levels in patients with CAD. Methods: Twenty two patients in our study consumed Oolong tea (1000 ml) or water for 1 month in our randomized cross-over study design. Results: There was a significant difference in plasma adiponectin levels before and after 1 month intake of Oolong tea (6.26±3.26 μg/ml versus 6.88±3.28 μg/ml, P<0.05), and in plasma level LDL particle size (25.02±0.67 nm versus 25.31±0.60 nm, P<0.01). The water-consuming control group showed no changes (6.28±3.28 μg/ml versus 6.23±3.21 μg/ml) in adiponectin levels or LDL particle sizes (25.03±0.70 nm versus 25.02±0.72 nm). We also observed a significant difference in hemoglobin A1c levels (7.23±4.45% versus 6.99±4.30%, P<0.05) before and after intake of Oolong tea. Conclusion: Oolong tea may have beneficial effects on the progression of atherosclerosis in patients with CAD.

Introduction

The Chinese belief that drinking tea enhances good health and longevity is gaining scientific merit [1]. Oolong tea is one of the three types of tea manufactured from tea leaves, the others being the black and green varieties. Oolong tea, which is commercially available in the United States, Japan and elsewhere, and served in Chinese restaurants around the world, has also been studied for its antioxidant properties [2], its effect on cardiovascular disease [3] and on obesity [4]. Adiponectin is a collagen-like plasma protein produced specifically by adipose tissue and is abundantly present in the circulation. Plasma adiponectin levels are known to be reduced in obesity [5], in patients with type 2 diabetes mellitus [6] and in coronary artery disease (CAD) [7]. Another study has already demonstrated that plasma adiponectin accumulates in the sub-endothelial space of the vascular wall at an early phase of catheter-induced injury and is detected around macrophages in the injured human aorta in the presence of thrombus [8]. These observations suggest that adiponectin may accumulate rapidly in the vascular wall when endothelial function is impaired and may modulate macrophage-to-foam cell transformation in vivo. On the other hand, the accumulated evidence of a number of studies suggests that low-density lipoprotein (LDL) particle size is a risk factor for CAD [9], [10], [11], [12]. Plasma level LDL particle sizes are significantly lower in patients with CAD than in controls, which finding corroborates with the etiology of atherosclerosis [13]. LDL smaller than 25.5 nm is known as small dense LDL. In this study, we prospectively investigated whether intake of Oolong tea influences plasma circulation levels of total cholesterol, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, serum triglyceride and plasma glucose levels in patients with CAD. In particular, we focused on the relationship between the plasma adiponectin levels, LDL particle size and long-term intake of Oolong tea in patients with CAD.

Section snippets

Patient population

Our study population (n=22) consisted of 12 patients with previous myocardial infarction and 10 patients with stable angina pectoris, treated as outpatients at Baba Memorial Hospital between 1 June 2001 and 10 September 2001, and who had already undergone diagnostic coronary angiography and percutaneous coronary intervention (Table 1). Patients who had or had had major surgery or trauma, serious active infectious diseases, malignancies, chronic inflammatory diseases, severe left-ventricular

Results

All 22 subjects participated in the study for the entire month of its duration, with none dropping out. There was no incidence of cardiac events during this time, which we defined as angina pectoris, heart failure, and acute myocardial infarction. We also saw no increase in blood pressure in any of our patients. There were no safety issues associated with ingestion of one litre of Oolong tea per day for subjects with coronary artery disease. There were no significant changes in body weight

Discussion

In the present study, we have shown first that long-term intake of Oolong tea increased plasma adiponectin levels and LDL particle size in our population of CAD patients. Our data also suggests that Oolong tea decreased hemoglobin A1c.

Conclusion

The present study is to our knowledge, the first to demonstrate that long-term intake of Oolong tea significantly increases plasma adiponectin levels and LDL particle size in patients with CAD. Moreover, the same Oolong tea regimen significantly decreased plasma levels of total cholesterol and hemoglobin A1c. We believe our findings suggest that long-term intake of Oolong tea may have a beneficial effect in inhibiting the progress of atherosclerosis in CAD subjects.

Acknowledgements

The authors wish to thank Tamami Ishii and Kanako Nitta for their secretarial assistance.

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Oolong tea increases plasma adiponectin levels and low-density lipoprotein particle size in patients with coronary artery disease

Abstract

Introduction

Section snippets

Patient population

Results

Discussion

Conclusion

Acknowledgements

J. Nutr.

Pharmacol. Res.

Atherosclerosis

Biochem. Biophys. Res. Commun.

Am. J. Med.

J. Biol. Chem.

Atherosclerosis

J. Nutr.

Total antioxidant capacity of teas by the ferric reducing/antioxidant power assay

J. Agric. Food Chem.

Anti-obesity action of Oolong tea

Int. J. Obes. Relat. Metab. Disord.

Molecular mechanism of metabolic syndrome X: contribution of adipocytokines adipocyte-derived bioactive substances

Ann. N.Y. Acad. Sci.

Plasma concentrations of a novel, adipose-specific protein, adiponectin, in type 2 diabetic patients

Arterioscler. Thromb. Vasc. Biol.

Novel modulator for endothelial adhesion molecules: adipocyte-derived plasma protein adiponectin

Circulation

An adipocyte-derived plasma protein, adiponectin, adheres to injured vascular walls

Horm. Metab. Res.

Adipocyte-derived plasma protein, adiponectin, suppresses lipid accumulation and class A scavenger receptor expression in human monocyte-derived macrophages

Circulation

Association of small low-density lipoprotein particles with the incidence of coronary artery disease in men and women

JAMA