Study of effects of Epigallocatectin-gallate (EGCG) on lipid profile and thereby cardiovascular risk

 

 

Abstract               Background: Nowadays use of green tea has been increasing worldwide due to the beneficial effects it has on cardiovascular system. The beneficial effects of green tea can be attributed to the presence of various catectins especially Epigallocatectin-gallate (EGCG) which by number of mechanisms has protective effect on our body. Objective: This study was designed to study the effects of EGCG present in green tea on Lipid profile in volunteers from Gotri, Vadodara. The lipid lowering effect of green tea and thereby reduction in cardiovascular risk was studied. Methods: 50 men over 40 years of age surveyed on their living habits were selected and divided in two random groups of 25 each. A 12-week trial was performed, in which one group was given 5 cups of green tea per daywhereas second group was given 10 cups per day. The subjects were instructed to maintain their usual dietary intake and normal physical activity. Results: Increased consumption of green tea was found to be linked with decreased concentrations of Serum total cholesterol (p value <0.0001), Serum TG (p<0.0001), and Serum LDL concentration (p< 0.0001) and an increase in Serum HDL concentration (p< 0.0001). Conclusion: From the above findings, in this study the effect of EGCG present in green tea on lipid parameters resulting in significant decrease in total cholesterol, serum triglycerides and Serum LDL where as a significant increase in levels of Serum HDL shows that regular consumption of green tea is protective against cardiovascular diseases.

Key Word: EGCG, Green tea, HDL, LDL, Triglycerides.

 

 

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in industrialized countries. According to World Health Organization report, CVDs were accounted for 29% of all global deaths in 2004 and about 23.6 million people will die from CVDs by 2030¹.The cardiovascular effects of green tea consumption have been extensively studied in human as well as in animal models^2,3. There are accumulating evidences from epidemiological and human interventional studies that consumption of green tea is associated with decreased CVD risks^4,7. The cardiovascular as well as other potential health benefits of green tea consumption have been previously reviewed^8,9. Green tea was found to be beneficial in patients with angiographically proven coronary artery disease (CAD)¹⁰. In a recent study in Chinese population, Wang et al.¹¹ showed that green tea consumption was associated with decreased prevalence of coronary artery disease that was defined as having at least one significant coronary artery stenosis. Dyslipidemias resulting from elevated levels of LDL cholesterol, phospholipids, triglycerides, and low plasma HDL-cholesterol levels act as a predisposing factor for the development of atherosclerotic plaques¹². In a cross-sectional study among 1371 Japanese men, Imai et al.¹³ found that increased green tea consumption was associated with decreased plasma levels of LDL, total cholesterol, and triglycerides, but increased levels of HDL. After metaanalysis of 14 eligible randomized controlled trials with a population of 1136, Zheng et al.¹⁴ concluded that consumption of green tea catectins is associated with significant reduction in total and LDL cholesterol levels, but not in HDL cholesterol. Green tea-mediated decreased plasma levels of total cholesterol and LDL cholesterol were consistently reported in a number of studies, however, the findings on the effects on triglycerides and HDL-cholesterol were mixed and inconsistent^15,23. Tea, from the plant Camellia sinensis, is consumed in different parts of the world as green, black, or Oolong tea. Among all of these, however, the most significant effects on human health have been observed with the consumption of green tea⁹. The first greentea was exported from India to Japan during the 17th century. It is estimated that about 2.5 million tons of tea leaves are produced each year throughout the world, with 20% produced as green tea, which is mainly consumed in Asia, some parts of North Africa, the United States, and Europe²⁴. The association between tea consumption, especially green tea, and human health has long been appreciated. Green tea contains polyphenols, which include flavanols, flavandiols, flavonoids, and phenolic acids; these compounds may account for up to 30% of the dry weight. Most of the green tea polyphenols (GTPs) are flavonols, commonly known as catechins. There are four kinds of catechins mainly find in green tea: epicatechin, epigallocatechin, epicatechin-3-gallate, and EGCG²⁵.The health-promoting effects of green tea are mainly attributed to its polyphenol content²⁶, particularly flavanols and flavonols, which represent30% of fresh leaf dry weight⁸. Recently, many of the aforementioned beneficial effects of green tea were attributed to its most abundant catechin,(-)-epigallocatechin-3-gallate (EGCG)^27,29. We have investigated the relationship between intake of green tea and different lipid parameters in Indian population with special mention to protective effects of green tea against cardiovascular diseases.

 

METHODOLOGY

The Study Population: The study population consisted of 50 local volunteers were selected after detailed surveying with a standard questionnaire mentioning their life style, eating habits, consumption of cigarettes and alcohol, history of any disease, medication and history of consumption of green tea.

Inclusion Criteria: All volunteers were above 40 years of age with normal glucose levels thereby excluding diabetes and with no other history of disease or regular medications. After detailed history, Urine examination, Lipid Profilewere carried out in all the volunteers. This was a randomized, controlled parallel trial consisting of a 12-week treatment period. The subjects were allocated into two groups A and B. Group A subjects were instructed to consume 4-5 cups of green tea per day whereas group B subjects were to consume 10 or more cups of green tea per day for 12 weeks. The subjects were instructed to maintain their usual dietary intake and physical activity. The subjects visited the medical institution at 4-week intervals after the run-in period. Eating and drinking, except for water, were prohibited from 10:00 PM on the day before the visit until the various measurements were completed.  We used Loose Green tea  with two tea spoon of green tea in every cup made.

Sample collection and Preparations: The Serum Lipid Profiles were measured 12 weeks after the commencement of the study. Serum Lipid Profiles were measured in a 12 hour fasting blood sample in both the group A and group B. 5 ml of blood was collected in a plain bulb for the estimation of Lipid profile. 2 ml of blood was collected in Fluoride bulb for blood sugar estimation. 10 to 12 hours of fasting prior to sample collection is required. EDTA plasma or serum is preferred. Blood should be centrifuged within 30 minutes or kept on ice until centrifugation.

Methods for different Parameters: Serum cholesterol was estimated by using Cholesterol Oxidase peroxidase (CHOD-PAP) method. Serum triglycerides estimated by GPO method. Serum HDL-C was estimated by using Phosphotungstic Acid (PTA) method, whereas Serum LDL-C was calculated by using Friedwald’s Equation.

Data Analysis: The data were obtained and plotted using a bar diagram. Important data were obtained indicating the comparison of serum Cholesterol, Serum TG, LDL-C and HDL-C levels two Groups A and B before start of the study and after 12 weeks of study. Statistical analysis was done and p value was calculated using t-test.

 

RESULTS AND OBSERVATIONS

Table 1: S. Cholesterol Levels in Group A (4-5 cups/day) pre and post study (after 12 weeks)

The table 1 shows that the mean serum cholesterol in group A pre study and post study was 187 mg/dl and 184 mg/dl, respectively. The standard deviation in case and control groups was 3.5 mg/dl and 3.49 mg/dl, respectively

 

Table 2: S. Cholesterol Levels in Group B (> 10 cups/day) pre and post study (after 12 weeks)

The table 2shows that the mean serum cholesterol in group B pre study and post study was 187 mg/dl and 177 mg/dl, respectively. The standard deviation in case and control groups was 3.5 mg/dl and 3.2 mg/dl, respectively

Table 3: S. Triglycerides Levels in Group A (4-5 cups/day) pre and post study (after 12 weeks)

The table 3 shows that the mean serum triglycerides in group A pre study and post study was 147 mg/dl and 140 mg/dl, respectively. The standard deviation in case and control groups was 3.2 mg/dl and 3.0 mg/dl, respectively

 

Table 4: S. Triglycerides Levels in Group B (> 10 cups/day) pre and post study (after 12 weeks)

The table 4 shows that the mean serum triglycerides in group B pre study and post study was 147 mg/dl and 128 mg/dl, respectively. The standard deviation in case and control groups was 3.2 mg/dl  and 2.7 mg/dl, respectively

                                                                            

Table 5: S. HDL Levels in Group A (4-5 cups/day) pre and post study (after 12 weeks)

The table 5shows that the mean serum HDL in group A pre study and post study was 36.4 mg/dl and 36.5 mg/dl, respectively. The standard deviation in case and control groups was 0.3 mg/dl and 0.31 mg/dl, respectively

 

Table 6: S. HDL Levels in Group B (> 10 cups/day) pre and post study (after 12 weeks)

The table 6shows that the mean serum HDL in group B pre study and post study was 36.4 mg/dl and 37.4 mg/dl, respectively. The standard deviation in case and control groups was 0.3 mg/dl  and 0.4 mg/dl, respectively.

 

Table 7: S. LDL Levels in Group A (4-5 cups/day) pre and post study (after 12 weeks)

The table 7 shows that the mean serum LDL in group A pre study and post study was 125 mg/dl and 114 mg/dl, respectively. The standard deviation in case and control groups was 4.2 mg/dl  and 3.1 mg/dl, respectively

 

Table 8: S. LDL Levels in Group B (> 10 cups/day) pre and post study (after 12 weeks)

The table 8 shows that the mean serum LDL in group B pre study and post study was 125 mg/dl and 110 mg/dl, respectively. The standard deviation in case and control groups was 4.2 mg/dl and 3.3 mg/dl, respectively.
DISCUSSION

Our study showed a close association between high consumption of green tea and normalisation of serum lipid parameters, which reflects cardiovascular diseases. Increased consumption of green tea, especially more than 10 cups a day, was associated with decreased serum total cholesterol and triglyceride concentrations; increased high density lipoprotein cholesterol concentrations and decreased low density and very low density lipoprotein cholesterol concentrations, resulting in a reduced atherogenicity.

Relation of Green tea consumption and total cholesterol: The difference observed between the pre and post study levels of cholesterol was highly significant in our study. (p value =0.0039 in group A and < 0.0001 in group B). Hence, in this study, increased intake of green tea decreases total cholesterol level significantly.

Relation of green tea consumption and serum triglycerides: The difference observed between the pre and post study levels of cholesterol was highly significant in our study. (p value < 0.0001 in both group A and  group B). Hence, in this study, increased intake of green tea decreases S. TG levels significantly.

Relation of green tea consumption and serum LDL-C: The difference observed between the pre and post study levels of Serum LDL-C was highly significant in our study. (p value < 0.0001 in both group A and  group B). Hence, in this study, increased intake of green tea decreases S. LDL-C levels significantly.

Relation of green tea consumption and serum HDL-C: The difference observed between the pre and post study levels of Serum HDL-C was highly significant in our study. (p value < 0.0001 in both group A and  group B). Hence, in this study, increased intake of green tea increases S. HDL-C levels significantly.

 

CONCLUSION

From our study it can be seen that continued consumption of green tea has got beneficial effect on cardiovascular injuries. Increased intake of green tea significantly reduces serum cholesterol, S. TG, and S. LDL-C whereas it singnificantly increase S. HDL-C levels thereby reducing the risk of atherosclerosis and cardiovascular diseases resulting due to that. The presence of EGCG in green tea is found to be cardiprotective and regulates lipid profile in a very positive manner thereby leading to a healthy heart.

 

REFERENCES

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