Intake Of Tea Catechins Research Articles

An analysis of health benefits of green tea

Green tea has presented to deliver health advantages meant for no. of illnesses, containing several kinds of, heartcancer, & liver disease. Green tea's catechin content, especially (−)-epigallocatechin-3-gallate, is responsible for many of its health benefits. underlying processes of green tea catechins & ir biological effects have studied in vitro & in animals. Green tea catechins have used in human trials to treat metabolic syndrome, which includes obesity, type 2 diabetes, & cardiovascular risk factors. Long-term intake of tea catechins might protect against obesity & type 2 diabetes caused by a high-fat diet, along with lower risk of coronary heart disease. Green tea's pharmacological & clinical effects should be monitored, & its mechanisms of action should be elucidated, in accordance with international st&ards.

Effect of tea catechins with caffeine on energy expenditure in middle-aged men and women: a randomized, double-blind, placebo-controlled, crossover trial

PurposeIt has been reported that tea catechins increase energy metabolism, but their effect on resting metabolic rate (RMR) remains under debate. This study aimed to examine the effect of repeated intake of tea catechins on energy metabolism in the resting state in middle-aged men and women.MethodsA total of 30 middle-aged men and women [13 women; age (mean ± SD) 52 ± 4 years; BMI 21.9 ± 2.2 kg/m2] were recruited. A randomized, double-blind, crossover study was conducted using a tea catechin-enriched beverage (611 mg catechins, 88 mg caffeine) and a placebo beverage (0 mg catechins, 81 mg caffeine) as test beverages. After 2 weeks of continuous test beverage intake, fasting RMR and energy expenditure (EE) after the ingestion of test beverage were measured. Measurements of forehead temperature (proxy for core temperature) and skin temperature were also obtained simultaneously.ResultsAmong participants who underwent measurements, 26 (10 women; mean age 52 ± 4 years; mean BMI 22.1 ± 2.1 kg/m2) were analyzed. The EE increased significantly after ingestion of the tea catechin beverage compared with the placebo beverage (placebo treatment: 5502 ± 757 kJ/day; catechin treatment: 5598 ± 800 kJ/day; P = 0.041). No between-treatment differences in fasting RMR or the respiratory quotient were detected. In addition, the forehead and skin temperature did not differ significantly between the placebo and catechin treatments.ConclusionThis study revealed that continuous intake of tea catechins with caffeine for 2 weeks significantly increased EE after ingestion of the tea catechin but not fasting RMR in middle-aged men and women.Clinical Trial Registry number and websiteThis trial was registered at www.umin.ac.jp/ctr/ as UMIN000025810 and UMIN000025811.

Tea catechins prevent contractile dysfunction in unloaded murine soleus muscle: A pilot study

Objective Extended periods of muscle disuse, physical inactivity, immobilization, and bedrest result in a loss of muscle mass and a decrease in muscle force, which are accompanied by an increase in oxidative stress. We investigated the effects of the intake of green tea catechins on unloading-induced muscle dysfunction in tail-suspended mice. Methods Ten-week-old male BALB/c mice were fed a purified control diet or a diet containing 0.5% tea catechins for 14 d. Thereafter, the mice were subjected to continuous tail suspension for 10 d. On the final day, muscle mass, contractile force production, antioxidant potential, and carbonylated protein levels were evaluated. Results Hind limb unloading caused a loss of soleus muscle weight and muscle force. Intake of tea catechins significantly inhibited the unloading-induced decrease in force in isolated soleus muscle by 19% compared with the control group, although tea catechins did not affect muscle weight. In addition, intake of tea catechins suppressed the decrease in antioxidant potential and the increase in carbonyl myofibrillar protein. Conclusion Ingestion of tea catechins minimized contractile dysfunction in skeletal muscle and muscle atrophy in unloaded muscle. This effect might be partly due to the lower oxidative modification of myofibrillar protein through the antioxidant activity of tea catechins.

Dietary Tea Catechins Increase Fecal Energy in Rats

Much attention has been paid to the beneficial health effect of tea catechins as one of the effective strategies to prevent obesity. The current study was carried out to investigate the role of tea catechins on the utilization of dietary energy sources in rats. The addition of 1% (w/w) tea catechins, mostly in gallate forms, to the diet brought about significant reductions in body weight gains and abdominal adipose tissue weights after 4-wk feeding periods compared to the control. A 2-d output of feces collected at the third week of feeding was significantly increased by a tea catechin diet (average dry weight+/-SD of 7.2+/-1.5 g) over that with a control diet (3.8+/-0.4 g). Only 0.1% of ingested starch appeared in the feces of rats fed the control diet, whereas 4.8% was excreted in the feces of the tea catechin group. Moreover, both apparent digestibility values for lipid and protein in the rats fed tea catechins were also lower than those of the control, suggesting that tea catechins increased the fecal excretion of these energy nutrients. Of the gross energy that the rats consumed from their respective diets during the fecal collection period, 1.6% (for control diet) and 5.8% (for tea catechin diet) were estimated to be excreted in feces. The energy loss originating from carbohydrate should contribute to the overall amount of energy in the feces, followed by protein. Intake of tea catechins suppressed the intestinal absorption of energy nutrients via the inhibition of digestive enzymes, which may at least partially influence the body fat reduction by tea catechins.

Lowering effect of tea catechin intake on adipose tissue weights in high fat fed rats

Lowering effect of tea catechin intake on adipose tissue weights in high fat fed rats

Tea catechin intake enhances fat utilization during prolonged exercise after endurance training in humans

Tea catechin intake enhances fat utilization during prolonged exercise after endurance training in humans

Effects of aerobic training and tea catechin intake on endurance capacity and substrate utilization during prolonged exercise in humans

Effects of aerobic training and tea catechin intake on endurance capacity and substrate utilization during prolonged exercise in humans

Green Tea Extract Thermogenesis-Induced Weight Loss by Epigallocatechin Gallate Inhibition of Catechol-O-Methyltransferase

Epidemiological studies have shown that intake of tea catechins is associated with a lower risk of cardiovascular disease. The antioxidative activity of tea-derived catechins has been extensively studied. Reports have shown that green tea extract intake is associated with increased weight loss due to diet-induced thermogenesis, which is generally attributed to the catechin epigallocatechin gallate. That catechin-polyphenols are known to be capable of inhibiting catechol-O-methyltransferase (the enzyme that degrades norepinephrine) is a possible explanation for why the green tea extract is effective in stimulating thermogenesis by epigallocatechin gallate to augment and prolong sympathetic stimulation of thermogenesis. Knowledge about thermogenesis-induced weight loss produced by green tea's epigallocatechin gallate and its ability to inhibit catechol-O-methyltransferase is important for health benefits and for prolonging the action of norepinephrine in the synaptic cleft.

Reduction of diet-induced obesity by a combination of tea-catechin intake and regular swimming

Obesity is a metabolic disorder resulting from imbalance between metabolizable energy intake and energy expenditure. It is known to be a strong risk factor for lifestyle-related diseases. Here, we investigated the effects of long-term intake of tea catechins (Cat) in combination with regular exercise (Ex) on the development of obesity in C57BL/6 mice. We compared body weight, adipose tissue mass, plasma parameters and beta-oxidation activity in mice fed a low-fat diet (5% triglyceride (TG); LF), a high-fat diet (30% TG; HF), a HF diet supplemented with 0.5% (w/w) tea Cat, a HF diet in addition to swimming Ex or a HF diet plus 0.5% tea Cat in addition to swimming Ex (Cat+Ex) for 15 weeks. Oxygen consumption and respiratory quotients were measured using indirect calorimetry. Tea-Cat intake in combination with swimming Ex suppressed HF diet-induced body-weight gain by 18 and 22%, respectively, compared to Ex and tea-Cat intake on their own. Visceral fat accumulation and the development of hyperinsulinemia and hyperleptinemia were also reduced in the HF+Cat+Ex group. Muscular beta-oxidation activity in this group was 69 and 52% higher, respectively, than that in the HF and HF+Cat groups. Lipid oxidation, determined using indirect calorimetry, was higher in the HF+Cat+Ex group, suggesting increased lipid utilization at the individual level. These results indicate that intake of tea Cat, together with regular Ex helps to reduce diet-induced obesity. This effect might be attributed, at least in part, to the activation of whole-body energy metabolism.

Effects of tea catechins on lipid metabolism and body fat accumulation

Long-term feeding of tea catechins suppressed body fat accumulation in high-fat diet-induced obesity in mice, and that their effects might be attributed, at least in part, to the activation of hepatic lipid metabolism. Consecutive intake of tea catechins (588 mg/day) reduced body fat, especially abdominal fat in humans. These results demonstrate that intake of tea catechins is beneficial for body fat accumulation.

Tea Catechins and Polyphenols: Health Effects, Metabolism, and Antioxidant Functions

Increasing interest in the health benefits of tea has led to the inclusion of tea extracts in dietary supplements and functional foods. However, epidemiologic evidence regarding the effects of tea consumption on cancer and cardiovascular disease risk is conflicting. While tea contains a number of bioactive chemicals, it is particularly rich in catechins, of which epigallocatechin gallate (EGCG) is the most abundant. Catechins and their derivatives are thought to contribute to the beneficial effects ascribed to tea. Tea catechins and polyphenols are effective scavengers of reactive oxygen species in vitro and may also function indirectly as antioxidants through their effects on transcription factors and enzyme activities. The fact that catechins are rapidly and extensively metabolized emphasizes the importance of demonstrating their antioxidant activity in vivo. In humans, modest transient increases in plasma antioxidant capacity have been demonstrated following the consumption of tea and green tea catechins. The effects of tea and green tea catechins on biomarkers of oxidative stress, especially oxidative DNA damage, appear very promising in animal models, but data on biomarkers of in vivo oxidative stress in humans are limited. Larger human studies examining the effects of tea and tea catechin intake on biomarkers of oxidative damage to lipids, proteins, and DNA are needed.Referee: Dr. Jeffrey Blumberg, USDA HNRC on Aging, Tufts University, Antioxidants Research Lab, 711 Washington Street, Boston, MA 02111-1524

The relation between single/double or repeated tea catechin ingestions and plasma antioxidant activity in humans

The purpose of this study was to investigate the effects of single/double or repeated intake of a normal amount of tea catechin on plasma catechin concentrations and antioxidant activity in young women. First, after an overnight fast, five healthy subjects were given water or single/double dose(s) of tea polyphenol extract (164 mg tea catechins containing 61% epigallocatechin gallate in 190 ml water). Blood samples were taken before and 30, 60 and 180 min after the ingestion. Second, 16 healthy subjects ingested the tea polyphenol extract three times a day at mealtimes for 7 days followed by withdrawal of tea polyphenol extract for 7 days. Blood samples were taken before and after ingestion, and 7 days after the withdrawal of tea catechin. Subjects were prohibited from drinking any beverages containing polyphenols or antioxidant supplements during the study period. Catechin and other antioxidant concentrations in the plasma were measured, and changes in antioxidant activity were evaluated by ferric reducing ability of plasma assay. Single/double ingestion of tea polyphenol extract did not cause an increase in the antioxidant activity. There was no also change in antioxidant activity after the ingestion of tea polyphenol extract for 7 days. Plasma-free epigallocatechin gallate concentration remained at the pre-study level; however, the plasma FRAP value decreased significantly at 7 days after the withdrawal of tea polyphenol extract. Decreases in endogenous antioxidants in the plasma, including vitamin C and bilirubin, were also observed 7 days after withdrawal of tea polyphenol. The results suggest that continuous daily intake of tea catechins affects the concentrations of endogenous antioxidants in the plasma and has the potential to maintain total antioxidant activity.

Absorption, metabolism and antioxidative effects of tea catechin in humans.

Green tea is consumed as a popular beverage in Japan and throughout the world. During the past decade, epidemiological studies have shown that tea catechin intake is associated with lower risk of cardiovascular disease. In vitro biochemical studies have reported that catechins, particularly epigallocatechin-3-gallate (EGCg), help to prevent oxidation of plasma low-density lipoprotein (LDL). LDL oxidation has been recognized to be an important step in the formation of atherosclerotic plaques and subsequent cardiovascular disease. Metabolic studies have shown that EGCg supplement is incorporated into human plasma at a maximum concentration of 4400 pmol/mL. Such concentrations would be enough to exert antioxidative activity in the blood stream. The potent antioxidant property of tea catechin may be beneficial in preventing the oxidation of LDL. It is of interest to examine the effect of green tea catechin supplementation on antioxidant capacity of plasma in humans by measuring plasma phosphatidylcholine hydroperoxide (PCOOH) as a marker of oxidized lipoproteins.