Green tea extract may boost blood vessel health
By Stephen Daniells, 31-May-2007

Related topics: Research, Phytochemicals, plant extracts, Cardiovascular health

The heart healthy reputation of epigallocatechin gallate (EGCG), the main extract from green tea, may be due in part to improvement in blood flow through the vessels, suggests a clinical trial from the US.

“EGCG acutely improves endothelial function in humans with coronary artery disease, and may account for a portion of the beneficial effects of flavonoid-rich food on endothelial function,” wrote the authors in the Journal of the American College of Nutrition.

European demand for tea extracts is currently surging, and this has seen companies such as DSM, with its Teavigo boasting 95 per cent purity of EGCG, and Taiyo International, with its Sunphenon claiming more than 90 per cent purity, position themselves firmly in specific catechin markets.

The researchers, led by Michael Widlansky from Boston University School of Medicine in collaboration with researchers from DSM Nutritional Products, state that epidemiological studies have demonstrated the benefits of dietary flavonoid intake. These may be related to improved endothelial function.

Widlansky and co-workers recruited 42 subjects to take part in the double blind, placebo-controlled, crossover design study. Subjects were randomly assigned to receive either an EGCG supplement or a placebo.

Blood flow in the arm, so-called brachial artery flow-mediated dilation (FMD), was measured by vascular ultrasound at baseline, and again after two hours after an initial dose of EGCG (300 mg) or placebo, and after two weeks of supplementation with EGCG (two 150 mg doses per day) or placebo. Before being crossed-over to the other intervention, the subjects underwent a one-week washout period.

Supplementation with the green tea extract was found to improve FMD from 7.1 to 8.6 per cent two hours after the initial 300 milligram dose, but was not significantly improved when measurements were taken 14 hours after the end of the two weeks of supplementation.

Blood levels of EGCG mirrored the vascular function, said the researchers, increasing from 2.6 to 92.8 nanograms per millilitre after the initial 300 mg dose, but returning approximately to baseline levels after two weeks (3.4 ng/ml).

The results add to an ever-growing body of science linking consumption to a wide range of health benefits, including lower risk of certain cancers, increased weight loss, improved heart health, and protection against Alzheimer’s.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin.

Source: Journal of the American College of Nutrition

Volume 26, Number 2, Pages 95-102

“Acute EGCG Supplementation Reverses Endothelial Dysfunction in Patients with Coronary Artery Disease”

Authors: M.E. Widlansky, N.M. Hamburg, E. Anter, M. Holbrook, D.F. Kahn, J.G. Elliott, J.F. Keaney, Jr., and J.A. Vita

Green tea’s heart benefits gain support
By Stephen Daniells, 07-Jul-2008

Related topics: Industry & Markets

Regular consumption of green tea may improve the function of endothelial cells – cells lining the walls of blood vessels – and boost cardiovascular health, according to new research from Greece.

The small study with 14 healthy adults found that the benefits of the beverage was not related to the caffeine, indicating the possible role of green tea polyphenols, previously linked to protection against certain kinds of cancers and Alzheimer’s.

The study is published in the European Journal of Cardiovascular Prevention and Rehabilitation.

“These findings have important clinical implications,” said study co-author Charalambos Vlachopoulos from Athens Medical School in Greece. “Tea consumption has been associated with reduced cardiovascular morbidity and mortality in several studies. Green tea is consumed less in the Western world than black tea, but it could be more beneficial because of the way it seems to improve endothelial function.

“In this same context, recent studies have also shown potent anticarcinogenic effects of green tea, attributed to its antioxidant properties,” added Dr Vlachopoulos.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

Study details

The Greek researchers randomly assigned the volunteers (average age 30) to one of three groups. The first receive six grams of green tea, the second received 125 mg of caffeine (equivalent to the caffeine dose from six grams of tea), and the third group received hot water.

The volunteers consumed each of the interventions on three separate occasions, and the effects on flow-mediated dilation (FMD), the measure of a blood vessel’s healthy ability to relax, measured 30, 90 and 120 minutes after consumption.

Green tea increased FMD by 3.9 per cent 30 minutes after consumption, while no changes in FMD were observed following consumption of caffeine or the hot water placebo.

“Green tea consumption has an acute beneficial effect on endothelial function, assessed with FMD of the brachial artery, in healthy individuals,” wrote the researchers.

“This may be involved in the beneficial effect of tea on cardiovascular risk,” they concluded.

Source: European Journal of Cardiovascular Prevention and Rehabilitation

2008, Volume 15, Pages 300-305

“The acute effect of green tea consumption on endothelial function in healthy individuals”

Authors: N. Alexopoulos, C. Vlachopoulos, K. Aznaouridis, K. Baou, C. Vasiliadou, P. Pietri, P. Xaplanteris, E. Stefanadi, C. Stefanadis

Green tea extract may lower blood pressure: study
By Stephen Daniells, 30-Oct-2008

Related topics: Industry & Markets

Daily supplements of extracts from green tea (Camellia sinensis) may reduce blood pressure, cholesterol and markers of oxidative stress, and all within three weeks, says a new study.

Reductions of systolic and diastolic blood pressures of 5 and 4 mmHg, respectively, were observed following daily supplements of green tea extracts, while total cholesterol levels were reduced by 10 mg/dL, according to findings of a randomised, double-blind, placebo-controlled, parallel study.

The study adds to an ever growing body of science reporting the potential health benefits of green tea and its extracts, which already range from reduced risks of cardiovascular disease, Alzheimer’s, and certain cancers.

Researchers from the University of Florida, Brigham and Women’s Hospital and Harvard Medical School, and the Nutritional Science Research Institute, Boston, report their findings in Nutrition.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

Study details

Meri Nantz and co-workers recruited 52 healthy men and 72 healthy women with an average age of 29 and randomly assigned them to receive daily supplements of green tea extract (Cardio Guard, containing 100 mg of L-theanine (Suntheanine, Taiyo International) and 200 mg of a decaffeinated catechin green tea extract (Sunphenon 90DCF, Taiyo International)) or placebo for three weeks.

At the end of the supplementation period the researchers found that total and LDL cholesterol levels had decreased by 10 and 9 mg/dL, respectively.

In addition to the blood pressure improvements, improvements in malondialdehyde (a marker of oxidative stress) and amyloid-alpha (a marker of chronic inflammation) were also recorded. Specifically, 12 and 42 per cent reductions, respectively, were observed.

“Camellia sinensis compounds may be an option for people who have mild to moderate high BP, elevated LDL cholesterol, elevated markers of inflammation, or a combination of these three CVD risk factors,” wrote the researchers.

“It may be helpful for individuals whose health care providers suggest a trial of diet and exercise before resorting to prescription medication,” they concluded.

High blood pressure (hypertension),defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg, is a major risk factor for cardiovascular disease (CVD) – a disease that causes almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.

Source: Nutrition
Published online ahead of print, 9 October 2008, doi: 10.1016/j.nut.2008.07.018
“Standardized capsule of Camellia sinensis lowers cardiovascular risk factors in a randomized, double-blind, placebo-controlled study”
Authors: M.P. Nantz, C.A. Rowe, J.F. Bukowski, S.S. Percival