Association of Green Tea with Risk of Coronary Heart Disease (CHD)

Abstract

Prospective studies on the association of green tea with risk of coronary heart disease (CHD) incidence were scarce. This study examined whether green tea can reduce CHD incidence and have a beneficial effect on CHD-related risk markers in middle-aged and older Chinese population. We included 19 471 participants who were free of CHD, stroke or cancer at baseline from September 2008 to June 2010, and were followed until October 2013. Cox proportional hazard models were used to examine the hazard ratios (HR) of CHD incidence in relation to green tea consumption. Linear regression models were used to evaluate the effect of green tea on 5-year changes of CHD-related biomarkers. Compared with non-green tea consumers, the multivariable-adjusted HR for CHD was 0.89 (95% CI, 0.81-0.98) in green tea consumers. Particularly, the reduced risk of CHD incidence with green tea consumption was more evident among participants who were male, more than 60 years old, overweight, or with diabetes mellitus. In addition, green tea consumption improved multiple CHD-related risk markers including total cholesterol, HDL-cholesterol, triglycerides, mean platelet volume, and uric acid. In conclusion, green tea consumption was associated with a reduced risk of CHD incidence in the middle-aged and older Chinese populations, and the association might be partly due to altered CHD-related biomarkers.

Cardiovascular disease (CVD) has become the leading cause of death and continues to exert a heavy burden in China. The number of patients with CVD increased to 290 million in 2014 with one out five Chinese adults suffering from the disease1. Coronary heart disease (CHD) accounts for the greatest proportion of CVD, and the prevalence of Chinese people with CHD is increasing substantially due to ageing, imbalanced diets, unhealthy behaviors and the raising standard of living. Thus, early prevention and control of CHD has become an extremely important public health concern.

Tea, a beverage made from leaves of Camellia sinensis, is the second most consumed beverage worldwide, only close to plain water. Tea was generally categorized into black, green and oolong tea according to the manufacturing process. Black tea, which covers about 78% of the total tea production, is usually consumed in the West; whereas green tea, which covers 20%, is consumed primarily in Japan, China and other East Asian countries5. A recent meta-analysis of prospective studies based mainly on evidence from black tea or unspecified tea showed that tea consumption was associated with a reduced risk of CHD, and found that the associations between tea consumption and cardiovascular outcomes differ according to sex, ethnicity, and the type of tea consumed. On the contrary, data on the association between green tea and CHD was limited and inconclusive. Several cohort studies have suggested an inverse association between green tea and CVD mortality. Although dose-response relationship between green tea and risk of CHD was reported in case-control and cross-sectional studies only two cohort studies have examined the impact of green tea consumption on risk of CHD incidence and no significant association was observed. On the other hand, favorable changes in CHD-related biomarkers, such as blood pressure, LDL cholesterol and glucose levels, were reported with green tea in randomized controlled trials which suggested a possible protective effect of green tea against CHD. However, most existing studies have only focused on one aspect: either green tea versus CHD, or green tea versus biomarkers; seldom studies have so far examined both of them on a same population.

Because of the high consumption of green tea in China and relatively high rate of CHD incidence and mortality, exploring the health effects of green tea on CHD might provide clues to resolve an important public health issue. Therefore, we aimed to 1) verify the relationship between green tea and CHD incidence in the Dongfeng-Tongji cohort; 2) examine whether the association between green tea and CHD was modified by differences in population characteristics and disease status; and 3) evaluate the effect of green tea on changes of multiple CHD-related biomarkers.

Resource: http://www.ncbi.nlm.nih.gov/
Resource: http://www.nutritionforest.com/

Assessing the Efficacy of Green Coffee Extract (GCE) as a Weight Loss Supplement

Abstract

The purpose of this paper is to assess the efficacy of green coffee extract (GCE) as a weight loss supplement, using data from human clinical trials. Electronic and nonelectronic searches were conducted to identify relevant articles, with no restrictions in time or language. Two independent reviewers extracted the data and assessed the methodological quality of included studies. Five eligible trials were identified, and three of these were included. All studies were associated with a high risk of bias. The meta-analytic result reveals a significant difference in body weight in GCE compared with placebo (mean difference: −2.47 kg; 95%CI: −4.23, −0.72). The magnitude of the effect is moderate, and there is significant heterogeneity amongst the studies. It is concluded that the results from these trials are promising, but the studies are all of poor methodological quality. More rigorous trials are needed to assess the usefulness of GCE as a weight loss tool.

Introduction

Overweight and obesity have become a serious health concern. Different weight management strategies are presently utilised, and a variety of weight loss supplements sold as “slimming aids” are readily available. However, the efficacy of some of these food supplements remains uncertain. One such supplement is the green coffee extract (GCE).

GCE is present in green or raw coffee. It is also present in roasted coffee, but much of the GCE is destroyed during the roasting process. Some GCE constituents, such as chlorogenic acid (CGA) can also be found in a variety of fruits and vegetables. The daily intake of CGA in persons drinking coffee varies from 0.5 to 1 g. The traditional method of extraction of GCE from green coffee bean, Coffea canephora robusta, involves the use of alcohol as a solvent. Extracted GCE is marketed as a weight loss supplement under a variety of brand names as a weight loss supplement such as “Coffee Slender”, and “Svetol”.

Evidence is accumulating from animal studies regarding the use of GCE as a weight loss supplement. In human subjects, coffee intake has been reported to be inversely associated with weight gain. Consumption of coffee has also been shown to produce changes in several glycaemic markers in older adults. Similarly, other research has indicated that the consumption of caffeinated coffee can lead to some reductions in long-term weight gain, an effect which is likely to be due to the known thermogenic effects of caffeine intake as well as effects of GCE and other pharmacologically active substances present in coffee. GCE has also been postulated to modify hormone secretion and glucose tolerance in humans. This effect is accomplished by facilitating the absorption of glucose from the distal, rather than the proximal part of the gastrointestinal tract.

The objective of this paper is to analyse the results of human clinical trials assessing the efficacy of GCE as a weight-reducing agent.

Resource: http://www.ncbi.nlm.nih.gov
Resource: http://www.nutritionforest.com/