Researchers from the Athens Medical School in Greece and published in the European Journal of Cardiovascular Prevention conducted a study which found drinking green tea may help prevent heart disease and stroke.
“A couple of cups a day would probably be a good dose for people,” researcher Charalambos Vlachopoulos said. “This is the first study to show these effects for green tea.”
Prior research has indicated that black tea can improve cardiovascular health, leading researchers suspect that green tea might even more effective. Many of the beneficial health effects of tea are attributed to its high content of antioxidant polyphenols, especially flavonoids. Most of these polyphenols are destroyed, however, by the fermentation process that makes tea black. This is why green tea has a water-extractable polyphenol content of between 30 and 40 percent, while the content in black tea is only 3 to 10 percent.
In the current study, researchers had 14 volunteers drink three different beverages, on three separate occasions: 6 grams of green tea, 125 milligrams of caffeine (the amount found in 6 grams of green tea) and a cup of hot water. They measured the flow-mediated dilation (FMD) of the participants’ blood vessels at 30, 90 and 120 minutes after consumption.
FMD is a widely used measure of blood vessel health.
The participants’ FMD improved by an average of 3.9 percent within 30 minutes of drinking green tea. It did not change at all in those who drank either the caffeine or hot water.
“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 [circulatory] function,” Vlachopoulos said.
He also noted that a number of studies have linked green tea to various cancer-fighting effects.
Caffeine is a naturally occurring substance found in the leaves, seeds or fruits of at least 100 different species worldwide and is part of a group of compounds known as methylxanthines. The most commonly known sources of caffeine are coffee, cocoa beans, cola nuts and tea leaves. People have enjoyed caffeinated beverages for many years. Caffeine is also added to specifically formulated ‘energy drinks’ and pharmaceutical products such as cold and flu remedies.
Coffee and tea also contain other dimethylxanthines; theophylline which has similar properties to caffeine and theobromine whose pharmacological actions is far less potent than caffeine and theophylline.
The amount of caffeine present in products depends on the type of the product, the serving size and the preparation method. For example a 190ml cup of tea contains 50mg of caffeine, one third less than the same amount of an instant cup of coffee (75mg). Table 1 below gives an indication of the amount of caffeine found in other drinks compared to tea:
Table 1 – Type of Product Caffeine (mg/ serving)
Tea All types 50mg/ 190ml serving (1)
Coffee Brewed (filter or percolated) 100-115mg/ 190ml serving (1)
Instant 75mg/ 190ml serving 1 Cola drinks Standard and Sugar Free 11-70mg/ 330 ml can (2)
‘Energy’ drinks All types 28-87mg/ 250ml serving (2)
Chocolate Bar 5.5-35.5mg/ 50g bar (2)
On average we consume 3.98mg of caffeine /kg body weight per day ie 239mg/ day for a 60kg person (3).
What is a safe intake of caffeine?
Up to 300mg/day (6 cups of tea) is considered moderate, with no evidence of harmful effects in the vast majority of the adult population. Some individuals are sensitive to caffeine and will feel effects at smaller doses than other individuals who are less sensitive. For this reason, these individuals may need to limit their caffeine intake.
Metabolism and Clearance
Caffeine does not accumulate in the body over a course of time and is normally excreted within several hours of consumption. The rate of caffeine elimination varies between individuals and this maybe as a result of genetic factors affecting the enzymes involved in the metabolism, or due to certain lifestyle factors e.g., smoking.
Children also metabolize caffeine at a quicker rate. Generally caffeine absorption is complete within about one hour after ingestion and the plasma concentration peaks (2) after about 60-90 minutes. The half-life of caffeine in the plasma is about 2.5 – 4.5 hours in healthy adults.
A number of different factors affect individual tolerance to caffeine, including the amount ingested, the frequency of caffeine consumption and individual metabolism. It is widely recognized that gradual tolerance develops with prolonged caffeine use.
Caffeine is a pharmacologically active substance, and depending on the dose, has a number of actions:-
• Central Nervous System Stimulant. A moderate caffeine intake can cause mild stimulation that maybe beneficial in terms of increased alertness, concentration, improved performance and decreased fatigue. (5-10) However, higher intakes may affect sleep, cause nervousness and an irregular heartbeat.
• Weak Bronchodilator. As a result, interest has been shown in its potential role as an asthma treatment. A number of studies have explored the effects of caffeine in asthma and the conclusions from a Cochrane Review suggest that caffeine appears to improve airways function modestly in people with asthma for up to four hours after consumption. (11)
• Diuretic. The diuretic action of caffeine may be due to an increase in renal blood flow, leading to an increased glomerular filtration rate (GFR), or due to a decreased re-absorption of sodium in the renal tubules. The diuretic effect of caffeine is dependent on the amount consumed and duration of intake e.g. the caffeine in tea does not have a diuretic effect unless the amount of tea consumed at one sitting contains more than 250-300mg of caffeine, equivalent to between 5 and 6 cups of tea. (12-17).
In fact, due to the volume of fluid that is drunk whilst enjoying a cup of tea, the British Dietetic Association advises that tea can contribute towards the daily recommended fluid intake of 1.5 to 2 litres.
• Cardiac Muscle Stimulant. Moderate caffeine consumption does not increase cardiac arrhythmias. (18)
If regular caffeine consumption is stopped abruptly, symptoms such as headaches, irritability and fatigue may occur. These effects are usually temporary, disappearing after a day or so and can be avoided if caffeine cessation is gradual.
Caffeine and Health
The role of caffeine in the development of certain diseases and conditions has been the subject of extensive research in recent years.
A number of studies investigating the impact of caffeine in the development of cancer have failed to establish a relationship. (19-22) In fact, tea is one of the richest sources of flavonoids, a powerful group of antioxidants. The role of antioxidants in the prevention of free radical damage has led to suggestions that tea maybe anti-carcinogenic. (23). Despite interesting preliminary research, further work is required to prove its beneficial effect in this area.
• Heart Disease.
The relationship between caffeine and heart disease has been the subject of a number of studies, and results from these and epidemiological studies have led to the conclusion that the ingestion of moderate amounts of caffeine is not associated with any increased risk of heart disease. (24-28) The Committee on Medical Aspects of Food Policy concluded that ‘there is little evidence that caffeine itself has any relation with CHD risk’ in the 1994 Nutritional Aspects of Cardiovascular Disease report. (29)
• Parkinson’s Disease.
Observational studies have suggested that caffeine may play a role in protecting against Parkinson’s disease, (30-31). Further research to try to determine the exact mechanism is required.
• Relief of headaches.
In a study of 301 regular headache sufferers, researchers found that a combination of ibuprofen and caffeine was better than either drug alone in relieving pain. (32)
Although a caffeine ‘pill’ was used in this trial, the researchers believed that caffeinated beverages would work just as well. However, they did warn that chronic headache sufferers should avoid caffeine because it might exacerbate symptoms. More work is required in this field before firm conclusions about caffeine and pain relief can be drawn.
Caffeine crosses the placenta and achieves blood and tissue concentrations in the foetus that are similar to maternal concentrations. For this reason recent advice published by the Food Standards Agency (33) recommends that pregnant women should limit their intake of caffeine consumption to less than 300mg/ day (equivalent to 6 cups of tea/ day). At this level there is little evidence to suggest that the health of the unborn child or mother is affected.
Despite recent publicity about caffeine, the fact remains that the consumption of caffeine at intakes of 300mg/ day has no adverse effects in the vast majority of the adult population. For this reason an average intake of three to four cups of tea (34) a day is well within the level considered safe.
Caffeine and Breastfeeding.
Caffeine enters breast-milk in small amounts (about 1% of the mother’s plasma level) but it does accumulate in smaller babies. Six to eight cups of coffee a day can result in infant wakefulness and hyperactivity. Smoking augments this effect. Of course the dose of caffeine from one cup of tea a day is nothing like the dose from several cups of coffee a day, but it makes sense to keep the dose the baby gets as low as possible.
1. Gray J (1998). Caffeine, coffee and health. Nutrition and Food Science 6:314- 319
2. Ministry of Agriculture, Fisheries and Food (MAFF) (1998). Survey of caffeine and other methylxanthines in energy drinks and other caffeine containing products (updated). Food Surveillance Information Sheet No. 144 (No. 103 revised). London
3. Barone JJ, et al. (1996) Caffeine consumption. Food and Chemical Toxicology 34:119-129
4. Graham TE (1997) The possible actions of methylxanthines on various tissues. In Reily T., Orme M (eds). The clinical pharmacology of sports and exercise. Elsevier Science, Amsterdam. 257-270
5. Lieberman HR, et al (1987). The effects of low doses of caffeine on human performance and mood. Psychopharmacology 93:308-312
6. Jarvis M. (1993). Does caffeine intake enhance absolute levels of cognitive performance? Psychopharmacology 110:45-52
7. Hindmarch I, et al. (1998). The effects of black tea and other beverages on aspects of cognition and psychomotor performance. Psychopharmacology 139(3) :230-238
8. Smith AP, et al (1990-91). Effects of caffeine given before and after lunch on sustained attention. Neuropsychobiology 23(3): 160-163
9. Durlach PJ, et al (1998). The effects of a low dose of caffeine on cognitive performance. Psychopharmacology 140(1):116-119
10. Battig K. (1986) Effect of coffee on the speed of subject-paced information processing. Neuropsychobiology;16(2-3):126-30
11. Bara AI, Barley EA. (2001) Caffeine for asthma (Cochrane Review). In: The Cochrane Library, 2, Oxford
12. Nussberger, J. et al. (1990) Caffeine-induced diuresis and atrial natriuretic peptides. Journal of cardiovascular Pharmacology, 15, 685-691
13. Neuhäuser-Berthold, M. et al. (1997) Coffee consumption and total body water homeostasis as measured by fluid balance and bioelectrical impedance analysis. Annals of Nutrition & Metabolism, 41, 29-36
14. Martof, M.T. and Knox, D.K. (1997) The effect of xanthines on fluid balance. Clinical Nursing Research, 6:186-196
15. Stookey, J.D. (1999) The diuretic effects of alcohol and caffeine and total water intake misclassification. European Journal of Epidemiology, 15, 181-188 16. Passmore AP et al (1987) Renal and cardiovascular effects of caffeine: a dose response study. Clin. Sci. 72(6), 749-56
17. Grandjean AC et al (2000) The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J. Am. Coll. Nutr. 19(5), 591-600
18. Myers MG. (1991) Caffeine and cardiac arrhythmias. Annals of Int Med,114:147-150
19. Rosenberg L. (1990). Coffee and tea consumption in relation to the risk of large bowel cancer. A Review of Epidemiological Studies. Cancer Letters 52:163-171
20. Jacobsen BK, et al (1986). Coffee drinking, Mortality and Cancer Incidence: Results from a Norwegian prospective study. Journal of the National Cancer Institute, 76:823-831
21. Gordis, L (1990). Consumption of methylxanthine-containing beverages and risk of pancreatic cancer. Cancer Letters, 52:1-12
22. Lubin F, et al. (1990) Consumption of methylxanthine-containing beverages and the risk of breast cancer. Cancer Letters, 53:81-90
23. Huang MT, et al (1992). Phenolic compounds in food and cancer prevention. Phenoloc Compounds in Food and Their Effects on Health II Washington: American Chemical Society Symposium Series.
24. Grobbee, DE, et al (1990). Coffee, caffeine and cardiovascular disease in men. The New England Journal of Medicine 323:1026-1032
25. Bak AAA, et al (1991). Caffeine, blood pressure, and serum lipids. Am J Clin Nut, 53:971-975
26. Stamler J, et al (1997). Relation of body mass and alcohol, nutrient, fiber and caffeine intakes to blood pressure in the special intervention and usual care 5 groups in the Multiple Risk Factor Intervention Trial. Am J Clin Nut, 65(Supp.): 338-365
27. Willett WC, et al (1996). Coffee consumption and coronary heart disease in women. A ten-year follow up. JAMA 275: 458-462
28. Woodward M, et al (1999). Coffee and tea consumption in the Scottish Heart Health Study follow-up: conflicting relations with coronary risk factors, coronary disease and all-cause mortality. J. Epidemiology and Community Health, 53: 481-487
29. Nutritional Aspects of Cardiovascular Disease (1994). Report of the Cardiovascular Review Group Committee on Medical Aspects of Food Policy. Department of Health 30. Ross G et al (2000). Association of coffee and caffeine intake with the risk of Parkinson Disease. JAMA, 283:2674-2679
31. Ascherio A, et al (2001). Prospective study of caffeine consumption and risk of Parkinson’s disease in men and women. Ann Neurol, 50(1):56-63
32. Diamond S, et al (2000). The Use of Ibuprofen Plus Caffeine to Treat Tensiontype Headache. Clinical Pharmacology and Therapeutics;68:312-319
33. Food Standards Agency (2001). Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment. Statement on the Reproductive Effects of Caffeine
Oriental and Indian cultures have known about the benefits of tea for thousands of years. The rest of the world is slowing catching up and being educated on the immense variety of healthy teas available.
The color of tea is usually dependent on the amount of post-harvesting processing.
White Teas – are the least processed and are not fermented. White tea is gaining in popularity as its significant health benefits become more widely recognized. White tea, as recent research has demonstrated, has the highest cancer fighting antioxidant polyphenols and has significantly lower caffeine content than black tea or green tea.
White tea can be considered a specialty tea due to its higher price, with some connoisseur blends of hand-picked limited-harvest white tea, grown in China, costing hundreds of dollars a pound.
Care needs to be taken when brewing white tea. Its delicate nature dictates for the best results, purified water at below boiling point should be used. Water which is too hot can result in a bitter tea, something you certainly want to avoid when you have paid for an expensive tea. White tea can be steeped for up to ten minutes, depending on your individual preference.
Green Teas – produced in China, Japan and Taiwan, are not fermented, low in caffeine and are well-known for health benefits, like boosting your immune system, reducing high blood pressure and cholesterol levels. Like white tea, green tea contains antioxidants, flavonoids, catechins vitamins C and E, and natural fluoride which protects against tooth decay.
For best results, green tea should be brewed with purified water, which is below boiling point. To avoid bitterness, do not infuse for longer than 1-2 minutes for fine leaf varieties, or 2-3 minutes for larger leaf varieties.
Black teas – are fully fermented teas and are the most commonly consumed. Hundreds of named varieties are available. Black tea is produced in large quantities in China, India, Sri Lanka, with smaller amounts coming from Australia, Indonesia, Kenya, Nepal and New Guinea. Specialty black teas are vastly different to the average tea bag, each having its own distinct color and taste.
Black teas also provide health benefits similar to green tea.
Oolong tea – combines the best qualities of both green and black teas. Semi-fermented, producing a refreshing, fragrant result. Adding milk is not recommended.
Wu-Yi Tea is a special Oolong tea well known for its weight loss properties.The raw leaves are sun-wilted and then bruised, which exposes their juices to the air, this causes the leaves to oxidize and start to turn brown like a cut fruit. They are only partially oxidized, giving them a rich, floral flavor. The tea is then fully dried which locks in the rich flavors that oolong tea is known to offer. The unique drying process that takes place in the creation of a tea that has many metabolic stimulating attributes. Find out more about Wu-Yi Tea HERE.
Jasmine tea – a non-fermented Chinese tea well known for its affinity with Asian food. Do not add milk.
Specialty flavored teas – a huge range of tea varieties blended with natural ingredients to add flavor. Additional ingredients can include:-
Spices – like anise, cinnamon, cardamom, cloves, fennel and black peppercorns.
Fruits – like apricot, cherry, apple, orange, blackcurrant, strawberry, lemon, lime, lychee, mango, raspberry and passionfruit.
Flowers – like hibiscus, lavender, rose, cornflower, calendula, and jasmine.
Nuts – like almond.
Other exotic ingredients like ginger, chocolate, mint, caramel, coconut, vanilla beans, bergamot and ginseng.
Specialty teas are consumed without milk.
Herbal teas – also known as herbal infusions – do not usually contain white, green or black teas, they consist of a variety of blends of herbs, spices and fruits chosen for particular health benefits. Herbal teas are usually named after the benefit they are promoting, e.g., “Recovery” blend for hangovers.
Ayurvedic teas – similar to herbal teas, but, based on ancient Indian healing principles, Ayurvedic teas aim to improve your life and extend your longevity.
Teas are a low calorie beverage choice (especially when no milk, sugar or honey is used), adding to your daily intake of water. Teas should be purchased as loose leaf teas, never teabags. Lemon juice can be added as a taste preference. Most teas can also be iced for a summer treat.
I’m not going to add much, I’ll just let the doctor have his say in this partial transcript from an Oprah Show episode featuring Dr Nicholas Perricone, which aired in November, 2004
“Oprah: Now I’ve read in your book that you said if I just replaced coffee with green tea instead, that I could lose 10 pounds in six weeks.
Dr. Perricone: Absolutely.
Oprah: Now really. How could that — what is the big deal about this?
Dr Perricone: Coffee has organic acids that raise your blood sugar, raise insulin. Insulin puts a lock on body fat. When you switch over to green tea, you get your caffeine, you’re all set, but you will drop your insulin levels and body fat will fall very rapidly. So 10 pounds in six weeks, I will guarantee it.
Oprah: I’m gonna do that. OK. That is so good! Whoo! That is great.”
— The Oprah Winfrey Show: “Look 10 Years Younger in 10 Days” – Nov 10, 2004
So, even if the doctor is only partly right, given that we’re all individuals who react differently, why wouldn’t you give green tea a try?
Green tea can help beat superbugs according to Egyptian scientists speaking today (Monday 31 March 2008) at theSociety for General Microbiology’s162nd meeting being held this week at the Edinburgh International Conference Centre.
The pharmacy researchers have shown that drinking green tea helps the action of important antibiotics in their fight against resistant superbugs, making them up to three times more effective.
Green tea is a very common beverage in Egypt, and it is quite likely that patients will drink green tea while taking antibiotics. The medical researchers wanted to find out if green tea would interfere with the action of the antibiotics, have no effect, or increase the medicines’ effects.
“We tested green tea in combination with antibiotics against 28 disease causing micro-organisms belonging to two different classes,” says Dr Mervat Kassem from the Faculty of Pharmacy at Alexandria University in Egypt. “In every single case green tea enhanced the bacteria-killing activity of the antibiotics. For example the killing effect of chloramphenicol was 99.99% better when taken with green tea than when taken on its own in some circumstances.”
Green tea also made 20% of drug-resistant bacteria susceptible to one of the cephalosporin antibiotics. These are important antibiotics that new drug resistant strains of bacteria have evolved to resist.
The results surprised the researchers, showing that in almost every case and for all types of antibiotics tested, drinking green tea at the same time as taking the medicines seemed to reduce the bacteria’s drug resistance, even in superbug strains, and increase the action of the antibiotics. In some cases, even a low concentration of green tea was effective.
“Our results show that we should consider more seriously the natural products we consume in our everyday life,” says Dr Kassem. “In the future, we will be looking at other natural herb products such as marjoram and thyme to see whether they also contain active compounds which can help in the battle against drug resistant bacteria”.
November 13, 2007 – News release from Purdue University
Citrus juice, vitamin C give staying power to green tea antioxidants
WEST LAFAYETTE, Ind. – To get more out of your next cup of tea, just add juice.
A study found that citrus juices enable more of green tea’s unique antioxidants to remain after simulated digestion, making the pairing even healthier than previously thought.
The study compared the effect of various beverage additives on catechins, naturally occurring antioxidants found in tea. Results suggest that complementing green tea with either citrus juices or vitamin C likely increases the amount of catechins available for the body to absorb.
“Although these results are preliminary, I think it’s encouraging that a big part of the puzzle comes down to simple chemistry,” said Mario Ferruzzi, assistant professor of food science at Purdue University and the study’s lead author.
Catechins (pronounced KA’-teh-kins), display health-promoting qualities and may be responsible for some of green tea’s reported health benefits, like reduced risk of cancer, heart attack and stroke. The problem, Ferruzzi said, is that catechins are relatively unstable in non-acidic environments, such as the intestines, and less than 20 percent of the total remains after digestion.
“Off the bat you are eliminating a large majority of the catechins from plain green tea,” Ferruzzi said. “We have to address this fact if we want to improve bodily absorption.”
Ferruzzi tested juices, creamers and other additives that are either commonly added to fresh-brewed tea or used to make ready-to-drink tea products by putting them through a model simulating gastric and small-intestinal digestion. Citrus juice increased recovered catechin levels by more than five times, the study found. Ascorbic acid, or vitamin C, used to increase shelf life in ready-to-drink products, increased recovered levels of the two most abundant catechins by sixfold and 13-fold, respectively.
The study, published this month in Molecular Nutrition and Food Research, also found that soy, dairy and rice milk appeared to have moderate stabilizing effects. But Ferruzzi said the result is misleading; a chemical interaction between milk proteins and tea catechins apparently helps shelter the complex from degradation, a force likely overcome by enzymes within a healthy human digestive system.
Lemons and tea go even better together than their popularity might suggest. Lemon juice caused 80 percent of tea’s catechins to remain, the study found. Following lemon, in terms of stabilizing power, were orange, lime and grapefruit juices. Ferruzzi said both vitamin C and citrus juices must interact with catechins to prevent their degradation in the intestines, although data made it clear that citrus juices have stabilizing effects beyond what would be predicted solely based on their vitamin C content.
“If you want more out of your green tea, add some citrus juice to your cup after brewing or pick a ready-to-drink product formulated with ascorbic acid,” Ferruzzi said.
Ready-to-drink green tea products should optimally contain 100-200 mg of catechins, but oftentimes do not have sufficient levels of tea extract since some people do not like green tea’s flavor, Ferruzzi said.
Although this study only examined green tea, Ferruzzi said he suspects that some of the results also could apply to black tea, which is produced by fermenting green tea. Many prefer black tea’s flavor, although it contains lower total levels of catechins.
Studies have shown catechins from the green tea plant, Camellia sinensis, are able to detoxify toxic chemicals, inhibit cancer cell activity and stimulate production of immune-strengthening enzymes. Finding methods to improve uptake of these catechins may, therefore, be important in improving health, part of the study’s goal, Ferruzzi said.
The study was funded by the National Institutes of Health.
Ferruzzi currently is conducting an in vivo study, or study on a live organism, to quantify the ability of juices and vitamin C to increase levels of catechins in the intestines and bloodstream of animals and, by extension, in humans. He collaborates with the NIH-funded Purdue Botanicals Research Center on this project.
“This next study is designed to get us past the limitations imposed by our digestive model, which is really just a simple screening process that relies on preset physiology parameters,” he said. “Human digestion is a lot more complicated.”
To see if juices and vitamin C actually increase catechin absorption, researchers will have to find out if increased levels of intestinal catechins translate to higher levels of absorbed catechins in live animals and humans. They also will need to better document effects upon catechin metabolism in order to prove, for instance, that increased levels of absorbed catechins are not leveled off by metabolic factors, Ferruzzi said.
“This study tells us a lot of interesting things, but it raises many questions that have yet to be answered,” he said.
Studies have confirmed green tea’s many health-enhancing conponents, which include catechin polyphenols (100% stronger than Vitamin C), polsaccarides, flavonoids, Vitamin bs, Vitamin E, R-Amino Butyric Acid and minerals.
Health benefits of Green Tea include:-
Strengthened immune function
Encourage healthier blood pressure, cholesterol and blood sugar levels
Encourage healthier intestinal flora which improves nutrient absorption
Improves oral health (controls dental decay, plaque build-up and bad breath)
Assists in weight loss (promotes thermogenesis and metabolsim of fat)
Remember to make you Organic Green Tea with Hexagon Water for an even better taste.
So, drink up and flash those pearly whites today!
Contents (per unit): 20 sachets x 2g
Oriyen Certified Organic Green Tea is prepared from finest grade, health-promoting green tea leaves from leading tea producer and exporter Stassen Group, Sri Lanka. Conforms strictly to the most stringent international standards for organic cultivation set by the International Federation of Agricultural Movements (IFOAM), Naturland of Germany, and the National Association for Sustainable Agriculture of Australia
• Great Taste Award, London, 2001
• Manufactured under ISO 9002 Quality System