Green tea extract benefit review
Supplement for weight loss?
Are there any side effects? Benefit and metabolism
For high blood pressure, diabetes, pregnancy, anxiety, liver damage
As fat burner, skin, acne, fat loss, appetite suppression or weight loss
February 1 2017
Green tea is consumed primarily in China, Japan, and a few countries in North Africa and the Middle East. In recent years it has become popular in Europe and North America and now green tea pills are touted for weight loss, as potent antioxidants, and for tumor prevention by many who practice Alternative Medicine. What does the research say about the benefits of such pills? Do supplements help with weight loss and are they an effective diet aid?
Weight loss natural product
We do not believe green tea extract, by itself, is effective as a natural weight loss pill. But, in combination with other nutraceuticals, it can be of benefit. For an effective product with green tea extract that helps you eat less, see Diet Rx, a natural appetite suppressant. Diet Rx, formulated by a well-known medical doctor, has been tested with patients and the results have been consistently effective.
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Best green tea diet supplement
There are a number of green tea diet supplements on the market, and since no studies have been done comparing all of them, it is impossible to say honestly which one of these products is the best green tea diet supplement.
Green tea has several potential health benefits that are slowly being discovered: Antioxidant, Alzheimer’s disease, cancer prevention, anti aging, heart health, blood thinning are some benefits or areas where research has been done.
Health benefit review
Human research is still early, but the potential health benefits ascribed to green tea include antioxidant effects, cancer prevention, antiviral effects, blood thinning properties, improving cardiovascular health, slowing mental decline, enhancing weight loss and fat burner, arthritis protection, and protecting the skin from the damage caused by ionizing radiation. Long term human research is required before we determine the appropriate dosage and amount of green tea or extract required to provide these health benefits. But, in the meantime, there is no reason to ingest too much of it.
Green tea and weight loss diet – a fat burner?
Green tea consumption is reportedly associated with various health-promoting properties. For example, it has been shown to promote fat oxidation in humans at rest and to prevent obesity and improve insulin sensitivity in mice.
Human studies regarding the benefit of green tea in weight loss have not shown consistent results. In one study mentioned below, daily consumption of green tea for 12 weeks reduced body fat but another study did not show weight loss with the use of green tea extract supplements. Scientists are still evaluating whether a green tea pill by itself leads to weight loss. See below for more green tea and weight loss research information. If you plan to drink green tea for weight loss or take it as a diet pill, avoid drinking after mid afternoon or early evening so that your sleep is not disturbed. It is quite possible that the combination of green tea extract and other supplements that influence appetite or metabolism could lead to weight loss.
Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial.
Clin Nutr. 2008. Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.
Seventy-eight of 100 obese women aged between 16 and 60 years with BMI>27 kg/m were randomly divided into Groups A and B. Group A received green tea extract while Group B took cellulose as a placebo, one capsule (400mg) three times each day for 12 weeks. The body weight (BW), body mass index (BMI) and waist circumflex (WC) were measured at the beginning of the study and after 12 weeks of treatment with green tea extract. There was only a 0.3% reduction in BW after 12 weeks of treatment with green tea extract. There was no statistical difference in % reduction in BW, BMI and WC between the green tea extract and placebo groups. Within group comparison revealed that the green tea extract group had significant reduction in LDL-cholesterol and triglyceride, and marked increase in the level of HDL-cholesterol, adiponectin and ghrelin. On the other hand, the placebo group showed significant reduction in triglyceride only, and a marked increase in the level of ghrelin alone. This study showed no statistical difference in % reduction in BW, BMI and WC between the green tea extract and placebo groups after 12 weeks of treatment. The intake of green tea extract (491 mg catechins containing 302 mg EGCG) for 12 weeks is considered safe.
Ingestion of a tea rich in catechins leads to a reduction in body fat and LDL in men.
American Journal of Clinical Nutrition, 2005
Catechins, the major component of green tea extract, have various physiologic effects. We investigated the effect of catechins from green tea on body fat reduction. Gealthy Japanese men were divided into 2 groups with similar BMI and waist circumference distributions. A 12-wk double-blind study was performed in which the subjects ingested 1 bottle oolong tea /d containing 690 mg catechins or 1 bottle oolong tea /d containing 22 mg catechins. Body weight, BMI, waist circumference, body fat mass, and subcutaneous fat area were significantly lower in the green tea extract group than in the control group. Daily consumption of green tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins from green tea might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity.
Anti-obesity effects of green tea: from bedside to bench.
Mol Nutr Food Res. 2006.
Green tea, green tea catechins, epicatechin, and epigallocatechin gallate (EGCG) have been demonstrated in cell culture and animal models of obesity to reduce adipocyte differentiation and proliferation, lipogenesis, fat mass, body weight, fat absorption, plasma levels of triglycerides, free fatty acids, cholesterol, glucose, insulin and leptin, as well as to increase beta-oxidation and thermogenesis. Adipose tissue, liver, intestine, and skeletal muscle are target organs of green tea, mediating its anti-obesity effects. Studies conducted with human subjects report reduced body weight and body fat, as well as increased fat oxidation and thermogenesis and thereby confirm findings in cell culture systems and animal models of obesity. There is still a need for well-designed and controlled clinical studies to validate the existing and encouraging human studies.
A 50 percent pure extraction of EGCG – a flavonoid which is the most potent of four major catechins in green tea, was examined by Dr. Stephane Bastianetto at the Douglas Mental Health University Institute, McGill University in Montreal. In the study, rats were fed food that contained Teawell 50, compared to a control group whose food did not contain the extract. Results showed that rats who ate Teawell 50 had an reduction of free radicals in a key region of the brain involved with learning and memory. This region is severely damaged when Alzheimer’s is present. “This suggests regular consumption of green tea may protect against the deleterious effects of oxidative stress, delaying or preventing age-related memory deficits,” said Dr. Bastianetto.
Anti aging benefit of drinking green tea
According to a study done with Japanese adults, those who consumed the most green tea were less likely to die from cardiovascular disease or any other cause, except cancer, than were the less-frequent green tea drinkers. Dr. Kuriyama and colleagues analyzed information on 40,530 Japanese adults, 40 to 79 years old, who participated in the Ohsaki National Health Insurance Cohort Study. The subjects, who were followed an 11 year period, were from a northeastern region of the country where most of the adults drink green tea three or more times per day. Adults who drank the most were the least likely to die from cardiovascular disease. Men who consumed at least five cups each day were less likely to die from any cause. Whereas, women who drank five or more cups of green tea each day were 23 percent less likely to die from any cause and 31 percent less likely to die from cardiovascular disease.
Comments: For the time being, if you don’t drink green tea, it may be a good idea to have a cup a day or a few times a week. If you already drink it on a daily basis, you could perhaps add another cup a day. It’s also possible that drinking a variety of teas may provide more benefit than just drinking additional green tea. Who’s to say other herbal teas (and there are so many to choose from) are not as healthy? Another option is to take a green tea extract supplement a few times a week. Avoid the use of the tea or the supplement after mid afternoon since the caffeine and stimulants may interfere with sleep. One factor to consider is that this study was done in Japan. Americans have a different diet and lifestyle. Will the results be similar in those on a Western diet?
Green tea extract capsules, when given to humans, increase the production of such as glutathione S-transferase (GST) enzymes which are helpful in detoxification and cancer prevention. Dr. H.-H. Sherry Chow, of the University of Arizona, Tucson, gave volunteers four green tea extract capsules, each containing 200 mg of epigallocatechin gallate, every morning prior to eating. This provided the equivalent amount of epigallocatechin gallate obtained from drinking 8 to 16 cups of green tea daily. Those with the lowest GST levels at the start of the study and who took the green tea extracts were found to have glutathione S-transferase enzymes increased. Those who had good levels of glutathione S-transferase did not have much of a change in their levels. Cancer Epidemiology, Biomarkers and Prevention, 2007.
Anti platelet activity
Anti-platelet (blood thinning) benefit of green tea catechins is mediated by inhibition of cytoplasmic calcium increase.
Green tea extract for arthritis and healthy joints
Some green tea catechins are chondroprotective (protecting cartilage) in lab studies, and that consumption of green tea may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown. Further studies will be required to determine whether these compounds access the joint space in sufficient concentration and in a form capable of providing efficacy when ingested as tea or capsule.
Several compounds in green tea have anti cancer potential, including against prostate cancer.
Pancreatic cancer – In mouse studies, green tea extract EGCG inhibits pancreatic cancer growth, invasion, metastasis and angiogenesis. Human studies will elucidate whether green tea extract could be used for the management of pancreatic cancer prevention and treatment.
Diabetes and blood sugar
Drinking green tea or taking a supplements does not seem to have a major role to play in lowering blood sugar, but the antioxidant effects are nevertheless beneficial for those with diabetes. Green tea may reduce advanced glycation end products and reduce the rate of collagen cross linking. It does not appear that it has much of an influence on blood sugar levels. However, this does not mean it is not beneficial to those with diabetes. Since it has has potent polyphenol antioxidants, drinking it or taking an extract may be helpful in terms of overall antioxidant status in the body. However, green tea extract may reduce collagen cross linking which is often a consequence of high blood sugar levels.
Green tea has preventive effects on both chronic inflammatory diseases and lifestyle-related diseases including cardiovascular disease.
Drinking green tea can protect heart arteries by keeping them flexible and relaxed, and therefore better able to withstand constant changes in blood pressure. Dr. Nikolaos Alexopoulos of Athens Medical School in Greece, reports that among 14 subjects, those who drank green tea showed greater dilation of their heart arteries on ultrasound 30 min. later than those drinking either diluted caffeine or hot water. Green tea flavonoids works on the lining of blood vessels, helping cells there to secrete the substances needed to relax the vessels and allow blood to flow more freely. These flavonoids act as antioxidants and help prevent inflammation in body tissue, that keep the vessels pliable. Flavonoids also protect against the formation of clots, which are the primary cause of heart attacks.
Exercise and athletic performance
The effects of EGCG on fat oxidation and endurance performance in male cyclists.
Int J Sport Nutr Exerc Metab. 2009. School of Sport and Exercise Science, Waikato Institute of Technology, Hamilton, New Zealand.
Eight male cyclists completed a study incorporating a 3-way crossover, randomized, placebo-controlled, diet-controlled research design. All participants received 3 different treatments (placebo 270 mg, EGCG 270 mg, and placebo 270 mg + caffeine 3 mg/kg) over a 6-day period and 1 hr before exercise testing. It was concluded that green-tea extract offers no additional benefit to cyclists over and above those achieved by using caffeine.
Flavanol epigallocatechin-3-gallate is shown to be a potent natural inhibitor of leukocyte elastase that may be used to reduce elastase-mediated progression to emphysema.
Black Tea — During black tea production, oxidation is promoted so that most of these substances are oxidized.
Green tea is prepared in such a way as to prevent the oxidation of green leaf polyphenols.
Oolong tea is a partially oxidized product. Of the approximately 3 million metric tons of dried tea manufactured, only 20% is green tea and less than 2% is oolong tea.
There are hundreds of types of green tea and countless green tea growing farms. Each batch will have a slightly different caffeine amount. In addition to caffeine, green tea has beneficial compounds mostly of the polyphenol class. A study done in Portugal evaluating various types of green tea found the caffeine content in green tea ranged between 140 to 340 mg per liter.
Green Tea side effects, safety, danger
A common green tea side effect is shallow sleep. Green tea has caffeine and methylxanthines, so avoid drinking or taking the capsules in the evening. We have not come across any other common green tea side effects at this time except this one caution:
Caution: In rare cases extracts from green tea have been reported to adversely affect the liver. Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice. If you plan to take green tea extract for prolonged periods, take a week off each month.
I have a question about the recent decision to put warning labels on supplements containing green tea extracts. it warns of possible liver damage. Are there supplements derived from green tea extracts which will not be easily identifiable by their labels?
A. The study that found green tea extract polyphenols may damage liver tissue used high doses injected into small mammals. Many Japanese drink green tea several cups a day without problems. We are not concerned that taking a green tea supplement at one capsule or tablet a few times a week would cause any liver problems.
Hepatotoxicity from green tea: a review of the literature and two unpublished cases.
Eur J Clin Pharmacol. 2009. Department of Physiology and Pharmacology, Sapienza, University of Rome, Rome, Italy.
To review the current literature on suspected green tea-related liver damage reactions and to describe two new cases reported within the framework of the Italian surveillance system of natural health products. A literature search of publication between 1999 and 2008 retrieved 34 cases of hepatitis. Histological examination of the liver revealed inflammatory reactions, cholestasis, occasional steatosis, and necrosis. There was one reported death. A positive rechallenge occurred in seven cases (20%). In the two new cases. Our analysis of the published case reports suggests a causal association between green tea and liver damage. The liver toxicity is probably due to epigallocatechin gallate or its metabolites which, under particular conditions related to the patient’s metabolism, can induce oxidative stress in the liver. In a few cases, toxicity related to concomitant medications could also be involved.
Safety of green tea extracts : a systematic review by the US Pharmacopeia.
Drug Saf. 2008. US Pharmacopeia, Rockville, Maryland, USA.
Recently, regulatory agencies in France and Spain suspended market authorization of a weight-loss product containing green tea extract because of liver harm concerns. This was followed by publication of adverse event case reports involving green tea products. In response, the US Pharmacopeia (USP) Dietary Supplement Information Expert Committee (DSI EC) systematically reviewed the safety information for green tea products in order to re-evaluate the current safety class to which these products are assigned. A total of 216 case reports on green tea products were analysed, including 34 reports concerning liver damage. Twenty-seven reports pertaining to liver damage were categorized as possible causality and seven as probable causality. Clinical pharmacokinetic and animal toxicological information indicated that consumption of green tea concentrated extracts on an empty stomach is more likely to lead to adverse effects than consumption in the fed state. Based on this safety review, the DSI EC determined that when dietary supplement products containing green tea extracts are used and formulated appropriately the Committee is unaware of significant safety issues that would prohibit monograph development, provided a caution statement is included in the labelling section.
What’s in green tea herb?
Fresh green tea leaf is unusually rich in Polyphenols which may constitute up to 30% of the dry leaf weight. Polyphenols include catechins, flavanols, chlorogenic acid, epigallocatechin gallate (EGCG), and one unique to tea, theogallin. Caffeine in green tea is present at an average level of 3% along with very small amounts of methylxanthines, theobromine and theophylline. The amino acid theanine (5-N-ethylglutamine) is also unique to tea. The compound EGCG has been shown to regulate dozens of disease-specific molecular targets.
Q. I see supplements of EGCG being sold in high dosages. Are these safe to take?
A. Consumers are switching from regular tea to green tea and other herbal teas. We are not big fans of taking large doses of isolated substances from herbs, such as a high amount of EGCG, preferring to take the whole powder or a less concentrated extract. Many people think the higher the dose of a substance they supplement, the healthier they will be, but that may not always be the case, and often is not the case. So, for the time being, we don’t see the need to take a high dose of EGCG.
Q. Can you possibly tell me how many mg of caffeine would be in 50 mg of green tea (leaf) extract?
A. This is impossible to say accurately since there are countless extract potencies of green tea and countless varieties of green tea leaf and herb. The level of caffeine could vary significantly between different extracts, growers, processors, and manufacturers.
Q. I had been drinking 2 to 4 cups of green tea for about ten years, mostly organic and de-caf. Last year I found out about the fluoride issue and also found out that green tea contains fluoride. I had no major health problems, just annoying sinus problems which would turn into infections several times/year. I did however have a lowered white cell count during this time (3.8-4.2) Then I developed sleep problems about 3 years ago and tried just about everything for them. I gave up drinking green tea last year (still have a cup of coffee with caffeine). Not only have my sleep problems ceased, but my white cell count is back to normal. I still can’t believe the results but I still won’t go back to drinking green tea. I did the research and I must be sensitive to fluoride.
A. Green tea, even decaf, has many compounds in it, such as catechins, that cause alertness. Drinking two to four cups of green tea a day will likely cause shallow sleep and at this time we are not convinced that it is the fluoride causing it.
Additional web articles of interest
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Gynostemma pentaphyllum herb health benefit
Gypenosides are saponins extract derived from Gynostemma pentaphyllum.