heart-health

Author: Mauro Serafini and João A.N Laranjinha and Leonor M Almeida and G Maiani

Mounting evidence shows that phenol-rich beverages exert strong antioxidant activity. However, in vivo evidence has produced conflicting results. In the present study, we studied the impact of the ingestion of 300 mL of black and green tea, alcohol-free red wine, alcohol-free white wine, or water on plasma total antioxidant capacity in five healthy volunteers. Red wine has the highest content of phenolics (3.63 ± 0.48 g QE/L), followed by green tea (2.82 ± 0.07 g QE/L), black tea (1.37 ± 0.15 g QE/L), and white wine (0.31 ± 0.01 g QE/L). Plasma total antioxidant capacity values of subjects who drank green tea rose at 30 min (P < 0.05). After black tea and red wine ingestion, the peaks were at 50 min (P < 0.05 and P < 0.01, respectively). No changes were observed in the control and white wine groups. Red wine and green tea were the most efficient in protecting low density lipoprotein from oxidation driven by peroxyl and ferril radicals, respectively. Phenol-rich beverages are a natural source of antioxidants; however, the phenolic content alone cannot be considered an index of their in vivo antioxidant activity.

Get the whole article here

Author: Yukiko Miura and Tsuyoshi Chiba and Shinji Miura and Isao Tomita and Keizo Umegaki and Masahiko Ikeda and Takako Tomita

Oxidation of low density lipoprotein (LDL) plays crucial roles in atherogenesis. We previously reported that green tea polyphenols (flavan 3-ols), especially epigallocatechingallate (EGCg) and epicatechingallate, exerted potent inhibitory effects on LDL oxidation in vitro. To examine whether intake of green tea polyphenols renders LDL resistant to ex vivo oxidation in humans, 22 male volunteers aged between 22 and 32 years were recruited and assigned the same dietary regimen for 2 weeks. After a 1-week baseline period, they were equally divided into two groups: control and tea. The tea group ingested 300 mg of green tea polyphenol extract twice daily for 1 week. Plasma EGCg concentration at the end of the experiment was 56 nmol/L on average (56% in free form) in the tea group; no EGCg was detected before the experiment. Plasma concentrations of lipids, ascorbate, α-tocopherol, and lipid peroxides did not change before and after the experiment in either group, but β-carotene was higher in the tea group (P< 0.01 by paired Student’st-test). LDL (0.1 mg/mL) was incubated with 5 μM Cu2+ and the oxidation was measured by absorbance at 234 nm. The lag time was significantly prolonged by 13.7 min in the tea group (P < 0.05 by paired Student’st-test, before versus after), whereas such a change was not observed in the control group. These results suggest that daily consumption of seven to eight cups (approximately 100 mL each cup) of green tea may increase resistance of LDL to in vivo oxidation, leading to reduction in the risk of cardiovascular diseases.

Get the whole article here

Author: C.A. Bursill and P.D. Roach

Get the whole article here

Author: C.A. Bursill and M. Abbey and P.D. Roach

Get the whole article here

Author: S. Gomikawa and Y. Ishikawa

Get the whole article here

Author: Jin Tae Hong and Seung Rel Ryu and Hye Jin Kim and Jong Kwon Lee and Sun Hee Lee and Dai Byung Kim and Yeo Pyo Yun and Jong Hoon Ryu and Byung Mu Lee and Pu Young Kim

Eicosanoids accumulation and formation of oxygen free radicals have been implicated in the pathogenesis of ischemia/reperfusion brain injury. In the present study, we examined whether green tea extract protects against ischemia/reperfusion-induced brain injury by minimizing eicosanoid accumulation and oxygen radical-induced oxidative damage in the brain. Green tea extract (0.5%) was orally administered to Wistar rats for 3 weeks before induction of ischemia. Ischemia was induced by the occlusion of middle cerebral arteries for 60 min and reperfusion was achieved for 24 h. Infarction volume in the ipsilateral hemisphere of ischemia/reperfusion animals was 114 ± 16 mm3 in the 0.5% green tea pretreated animals compared to 180 ± 54 mm3 in left hemisphere of nontreated animals. Green tea extract (0.5%) also reduced ischemia/reperfusion-induced eicosanoid concentration: Leukotriene C4 (from 245 ± 51 to186 ± 22), prostoglandin E2 (from 306 ± 71 to 212 ± 43) and thromboxane A2 (327 ± 69 to 251 ± 87 ng/mg protein). Ischemia/reperfusion-induced increases of hydrogen peroxide level (from 688 ± 76 to 501 ± 99 nmole/mg protein), lipid peroxidation products (from 1010 ± 110 to 820 ± 70 nmole/mg protein) and 8-oxodG formation (from 1.3 ± 0.3 to 0.8 ± 0.2 ng/μg DNA, ×10−2) were also reduced. Moreover, 0.5% green tea extract also reduced the apoptotic cell number (from 44 ± 11 to 29 ± 1 in the striatum, and from 72 ± 11 to 42 ± 5 apoptotic cells/high power field in the cortex region). Green tea extract pretreatment also promoted recovery from the ischemia/reperfusion-induced inhibition of active avoidance. The present study shows that the minimizing effect of green tea extract on the eicosanoid accumulation and oxidative damage in addition to the reduction of neuronal cell death could eventually result in protective effect on the ischemia/reperfusion-induced brain injury and behavior deficit.

Get the whole article here

Author: Shizuka Sasazuki and Hiroko Kodama and Kouichi Yoshimasu and Ying Liu and Masakazu Washio and Keitaro Tanaka and Shoji Tokunaga and Suminori Kono and Hidekazu Arai and Yoshitaka Doi and Tomoki Kawano and Osamu Nakagaki and Kazuyuki Takada and Samon Koyanagi and Koji Hiyamuta and Takanobu Nii and Kazuyuki Shirai and Munehito Ideishi and Kikuo Arakawa and Masahiro Mohri and Akira Takeshita

PURPOSE: To examine the relation between green tea consumption and arteriographically determined coronary atherosclerosis. METHODS: Study subjects were 512 patients (302 men and 210 women) aged 30 years or older who underwent coronary arteriography for the first time at four hospitals in Fukuoka City or one hospital in an adjacent city between September 1996 and August 1997. Lifestyle characteristics including green tea consumption were ascertained before arteriography by a questionnaire supported with interview. RESULTS: 117 men (38.7%) and 50 women (23.8%) had significant stenosis of one or more coronary arteries. Green tea consumption tended to be inversely associated with coronary atherosclerosis in men, but not in women. An evident, protective association between green tea and coronary atherosclerosis was observed in a subgroup of 262 men excluding those under dietary or drug treatment for diabetes mellitus. In this subgroup, after adjustment for traditional coronary risk factors and coffee, odds ratios of significant stenosis for consumption of 2–3 cups and 4 or more cups per day were 0.5 (95% confidence interval 0.2–1.2) and 0.4 (0.2–0.9), respectively, as compared with a consumption of one cup per day or less. CONCLUSIONS: The results indicate that green tea may be protective against coronary atherosclerosis at least in men.

Get the whole article here

Author: Ming-Hua Yang and Cheng-Hsin Wang and Hsiao-Ling Chen

The main goal of this study was to compare effects of ethanol-soluble fractions prepared from various types of teas on sucrose-induced hyperlipidemia in 5-week old male Sprague-Dawley rats. Rats (n = 6–8 per group) weighed approximately 200 g were randomly divided into control diet, sucrose-rich diet, green tea, oolong tea and black tea groups. Control-diet group was provided with modified AIN-93 diet while the others consumed sucrose-rich diet. Tea extracts (1% w/v) were supplied in the drink for green tea, oolong tea and black tea groups. Results indicated sucrose-rich diet induced hypertriglyceridemia and hypercholesterolemia. Food intake was reduced by oolong tea extract. Consuming oolong and black tea extracts also significantly decreased body weight gains and food efficiency. Hypertriglyceridemia was normalized by green and black tea drink on day 18 and by oolong tea extract on day 25, respectively. Hypercholesterolemia was normalized by green tea on day 18 and by oolong tea and black tea on day 25, respectively. Plasma HDL-cholesterol concentrations were not affected by any tea extract. The triglyeride content in the liver as well as the cholesterol content in the heart of rats fed sucrose-rich diet were elevated and were normalized by all types of tea drink tested. Although green and oolong tea extracts contained similar composition of catechin, our findings suggest green tea exerted greater antihyperlipidemic effect than oolong tea. Apparent fat absorption may be one of the mechanisms by which green tea reduced hyperlipidemia as well as fat storage in the liver and heart of rats consumed sucrose-rich diet.

Get the whole article here

Author: Lynnette R. Ferguson

Polyphenols are a large and diverse class of compounds, many of which occur naturally in a range of food plants. The flavonoids are the largest and best-studied group of these. A range of plant polyphenols are either being actively developed or currently sold as dietary supplements and/or herbal remedies. Although, these compounds play no known role in nutrition (non-nutrients), many of them have properties including antioxidant, anti-mutagenic, anti-oestrogenic, anti-carcinogenic and anti-inflammatory effects that might potentially be beneficial in preventing disease and protecting the stability of the genome. However not all polyphenols and not all actions of individual polyphenols are necessarily beneficial. Some have mutagenic and/or pro-oxidant effects, as well as interfering with essential biochemical pathways including topoisomerase enzyme activities, prostanoid biosynthesis and signal transduction. There is a very large amount of in vitro data available, but far fewer animal studies, and these are not necessarily predictive of human effects because of differences in bacterial and hepatic metabolism of polyphenols between species. Epidemiological studies suggest that high green tea consumption in the Japanese population and moderate red wine consumption in the French population may be beneficial for heart disease and cancer, and these effects may relate to specific polyphenols. A small number of adequately controlled human intervention studies suggest that some, but not all polyphenol extracts or high polyphenol diets may lead to transitory changes in the antioxidative capacity of plasma in humans. However, none of these studies have adequately considered long-term effects on DNA or the chromosome and unequivocally associated these with polyphenol uptake. Furthermore, clinical trials have required intravenously administered polyphenols at concentrations around 1400 mg/m2 before effects are seen. These plasma concentrations are unlikely to be achieved using the dietary supplements currently available. More focused human studies are necessary before recommending specific polyphenolic supplements at specific doses in the human population.

Get the whole article here

Author: Jin Tae Hong and Seung Rel Ryu and Hye Jin Kim and Jong Kwon Lee and Sun Hee Lee and Yeo Pyo Yun and Byung Mu Lee and Pu Young Kim

Free radical-induced oxidative damages of macromolecules and cell death are important factors in the pathogenesis of ischemia/reperfusion brain injury. In the present study, an investigation as to whether green tea extract reduces ischemia/reperfusion-induced brain injury in Mongolian gerbils was conducted. The effect of green tea on the ischemia/reperfusion-induced production of hydrogen peroxide, lipid peroxidation and oxidative DNA damage (formation of 8-hydroxydeoxyguanosine), and cell death in addition to locomotor activity was studied. Two doses (0.5 or 2%) of green tea extract were added into the drinking water and to be accessed by animals ad libitum for 3 weeks prior to the induction of ischemia. A global ischemia was induced by the bilateral occlusion of the common carotid arteries for 5 min. Reperfusion was achieved by releasing the occlusion and restoring blood circulation for 48 h. The infarction volumes were 112±31 mm3 and 76±11 mm3 in the 0.5 and 2% green tea pretreated animals compared to 189±12 mm3 in the ischemia/reperfusion animals. Green tea extract also reduced the levels of ischemia/reperfusion-induced hydrogen peroxide (from 1470±170 to 1034±46 and 555±30 nmole/mg protein), lipid peroxidation products (from 1410±210 to 930±40 and 330±20 nmole/mg protein) and 8-oxodG (from 3.9±0.1 to 2.8±0.3 and1.9±0.3 ng/μg DNA, ×10−2) by pretreatment of 0.5 or 2% green tea for 3 weeks, respectively. Moreover, green tea also reduced the number of ischemia/reperfusion-induced apoptotic cells (from 59±12 to 37±8, 15±11 apoptotic cells/high power field in the striatum region) and locomotor activity (from 15140±2940 to 3900±600 and 4100±1200). This study therefore suggests that green tea may be a useful agent for the prevention of cerebral ischemia damage.

Get the whole article here