Healthiest Tea, Green Tea, White Tea or Black tea.
What is the Healthiest Tea to drink, is it Green Tea, White Tea or Black tea.
Is there one tea that you should drink more of on a daily basis.
We know that these different teas have different health benefits.
Maybe there is no one tea that fits all in terms of health, perhaps we need to try a few to get the full healthy benefits from drinking teas.
What follows is information of the possible health benefits of the three main types of drinking teas.
Black tea health information from Wikipedia
Health and nutrition
Main article: Health effects of Black tea
Plain black tea without sweeteners or additives contains negligible quantities of calories, protein, sodium, and fat. Some flavored tea with different herbs added may have less than 1 gram of carbohydrates. All teas from the camellia tea plant are rich in polyphenols, which are a type of antioxidant.
Benefits
A 2001 Boston University study has concluded that short and long-term black tea consumption reverses endothelial vasomotor dysfunction in patients with coronary artery disease. This finding may partly explain the association between tea intake and decreased cardiovascular disease events. [4]
In 2006, a German study concluded that the addition of milk prevents vascular protective effects of tea. [5]
Theaflavin-3-gallate, a theaflavin derivative found in black tea, could reduce the incorporation of cholesterol into mixed micelles[6].
Green tea health information from Wikipedia
Health effects
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Main article: Health effects of tea
Green tea contains polyphenols which are thought to improve health, particularly catechins, the most abundant of which is epigallocatechin gallate. In vitro and animal studies as well as preliminary observational and clinical studies of humans suggest that green tea can reduce the risk of cardiovascular disease and cancer as well as beneficially impact bone density, cognitive function, dental cavities, and kidney stones. However, the human studies are sometimes mixed and inconsistent.[5] Green tea also contains carotenoids, tocopherols, ascorbic acid (vitamin C), minerals such as chromium, manganese, selenium or zinc, and certain phytochemical compounds. It is a more potent antioxidant than black tea,[5] although black tea has substances which green tea does not such as theaflavin.
Green tea consumption is associated with reduced heart disease in epidemiological studies. Animal studies have found that it can reduce cholesterol. However, several small, brief human trials found that tea consumption did not reduce cholesterol in humans. In 2003 a randomized clinical trial found that a green tea extract with added theaflavin from black tea reduced cholesterol.[6]
In a study performed at Birmingham (UK) University, it was shown that average fat oxidation rates were 17% higher after ingestion of green tea extract than after ingestion of a placebo.[7] Similarly the contribution of fat oxidation to total energy expenditure was also significantly higher by a similar percentage following ingestion of green tea extract. This implies that ingestion of green tea extract can not only increase fat oxidation during moderately intensive exercise but also improve insulin sensitivity and glucose tolerance in healthy young men.
A recent study looked at the effects of short term green tea consumption on a group of students between the ages of 19–37. Participants were asked not to alter their diet and to drink 4 cups of green tea per day for 14 days. The results showed that short term consumption of commercial green tea reduces systolic and diastolic Blood Pressure, fasting total cholesterol, body fat and body weight. These results suggest a role for green tea in decreasing established potential cardiovascular risk factors. This study also suggests that reductions may be more pronounced in the overweight population where a significant proportion are obese and have a high risk of cardiovascular disease.[8]
In a study performed at the Israel Institute of Technology, Technion, it was shown that the main antioxidant polyphenol of green tea extract, EGCG, when fed to mice induced with Parkinson's and Alzheimer's disease, helped to protect brain cells from dying, as well as 'rescuing' already damaged neurons in the brain, a phenomenon called neurorescue or neurorestoration. The findings of the study, led by Dr. Silvia Mandell, were presented at the Fourth International Scientific Symposium on Tea and Human Health in Washington D.C., in 2007. Resulting tests underway in China, under the auspices of the Michael J. Fox Foundation, are being held on early Parkinson's patients.[9]
A study [10] performed at the National institute of Chemistry in Ljubljana, Slovenia, demonstrated that EGCG from green tea inhibits an essential bacterial enzyme gyrase by binding to the ATP binding site of the B subunit. This activity probably contributes to the antimicrobial activity of green tea extract and may be responsible for the effectiveness of green tea in oral hygiene.
In a recent case-control study of the eating habits of 2,018 women, consumption of mushrooms and green tea was linked to a 90% lower occurrence of breast cancer.[11]
A recent study on rats at the University of Hong Kong, published in the February issue of Journal of Agricultural and Food Chemistry, found that the catechins in green tea were absorbed by the lens, retina and other parts of the eye[12]. The absorbed catechins reduced oxidative stress in the eye for up to 20 hours, suggesting that green tea may be effective in preventing glaucoma and other diseases of the eye.
History
Tea consumption had its origin in China more than 4000 years ago.[13] Green tea has been used as both a beverage and a method of traditional medicine in most of Asia, including China, Japan, Vietnam, Korea, India and Thailand, to help everything from controlling bleeding and helping heal wounds to regulating body temperature, blood sugar and promoting digestion.
The Kissa Yojoki (Book of Tea), written by Zen priest Eisai in 1191, describes how drinking green tea can have a positive effect on the five vital organs, especially the heart. The book discusses tea's medicinal qualities, which include easing the effects of alcohol, acting as a stimulant, curing blotchiness, quenching thirst, eliminating indigestion, curing beriberi disease, preventing fatigue, and improving urinary and brain function. Part One also explains the shapes of tea plants, tea flowers, and tea leaves, and covers how to grow tea plants and process tea leaves. In Part Two, the book discusses the specific dosage and method required for individual physical ailments.
Unproven claims
Green tea has been credited with providing a wide variety of health benefits, many of which have not been validated by scientific evidence. These claims and any for which academic citations are currently missing are listed here:
* Stopping certain neurodegenerative diseases such as Alzheimer's and Parkinson's.
* The prevention and treatment of cancer.[14][15] See also flavonoid and cancer.
* Treating multiple sclerosis.[16]
* Preventing the degradation of cell membranes by neutralizing the spread of free radicals which occur during oxidation process.[17][dubious – discuss]
* Reducing the negative effects of LDL cholesterol (bad cholesterol) by lowering levels of triglycerides and increasing the production of HDL cholesterol (good cholesterol).
* Joy Bauer, a New York City nutritionist, says [the catechins in green tea] increase levels of the metabolism speeding brain chemical norepinephrine (noradrenaline).
* Japanese researchers claim that drinking five cups of green tea a day can burn 70 to 80 extra calories. Dr. Nicholas Perricone, a self-proclaimed anti-aging specialist, appeared on The Oprah Winfrey Show and told Oprah's viewers they can lose 10 lbs (4.5 kg) in 6 weeks drinking green tea instead of coffee.
* Some green tea lovers commonly restrict their intake because of the stimulants it contains — equivalent to about a third the amount of caffeine as is found in coffee[2][dubious – discuss]. Too much caffeine can cause nausea, insomnia, or frequent urination.[18]
United States Food and Drug Administration
The article Tea: A Story of Serendipity[19] appeared in the March 1996 issue of the United States Food and Drug Administration Consumer Magazine and looked at the potential benefits of green tea. At that time the FDA had not done any reviews of the potential benefits of green tea and were waiting to do so until health claims were filed. The FDA have since denied two petitions to make qualified health claims as to the health benefits of green tea.[20]
On June 30, 2005, in response to "Green Tea and Reduced Risk of Cancer Health Claim", the FDA stated: "FDA concludes that there is no credible evidence to support qualified health claims for green tea consumption and a reduced risk of gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, and combined cancers. Thus, FDA is denying these claims. However, FDA concludes that there is very limited credible evidence for qualified health claims specifically for green tea and breast cancer and for green tea and prostate cancer, provided that the qualified claims are appropriately worded so as to not mislead consumers." [21]
On May 9, 2006, in response to "Green Tea and Reduced Risk of Cardiovascular Disease", the FDA concluded "there is no credible evidence to support qualified health claims for green tea or green tea extract and a reduction of a number of risk factors associated with CVD." [22]
However in October 2006, the FDA approved an ointment based on green tea. New Drug Application (NDA) number N021902, for kunecatechins ointment 15% (proprietary name Veregen) was approved on October 31, 2006,[23] and added to the "Prescription Drug Product List" in October 2006.[24] Kunecatechins ointment is indicated for the topical treatment of external genital and perianal warts.[25]
Scientific studies
According to research reported at the Sixth International Conference on Frontiers in Cancer Prevention, sponsored by the American Association for Cancer Research, a standardized green tea polyphenol preparation (Polyphenon E) limits the growth of colorectal tumors in rats treated with a substance that causes the cancer. "Our findings show that rats fed a diet containing Polyphenon E are less than half as likely to develop colon cancer," Dr. Hang Xiao, from the Ernest Mario School of Pharmacy at Rutgers University, Piscataway, New Jersey, noted in a statement.
A 2006 study published in the September 13 issue of the Journal of the American Medical Association concluded "Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer." The study, conducted by the Tohoku University School of Public Policy in Japan, followed 40,530 Japanese adults, ages 40–79, with no history of stroke, coronary heart disease, or cancer at baseline beginning in 1994. The study followed all participants for up to 11 years for death from all causes and for up to 7 years for death from a specific cause. Participants who consumed 5 or more cups of tea per day had a 16 percent lower risk of all-cause mortality and a 26 percent lower risk of cardiovascular disease ("CVD") than participants who consumed less than one cup of tea per day. The study also states, "If green tea does protect humans against CVD or cancer, it is expected that consumption of this beverage would substantially contribute to the prolonging of life expectancy, given that CVD and cancer are the two leading causes of death worldwide."[26] [27]
A study in the February 2006 edition of the American Journal of Clinical Nutrition concluded "A higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans."[28][29][dubious – discuss]
In May 2006, researchers at Yale University School of Medicine weighed in on the issue with a review article that looked at more than 100 studies on the health benefits of green tea. They pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking. They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides high levels of polyphenols and other antioxidants. These compounds may work in several ways to improve cardiovascular health, including preventing blood platelets from sticking together (This anticoagulant effect is the reason doctors warn surgical patients to avoid green tea prior to procedures that rely on a patient's clotting ability) and improving cholesterol levels, said the researchers, whose study appeared in the May issue of the Journal of the American College of Surgeons. Specifically, green tea may prevent the oxidation of LDL cholesterol (the "bad" type), which, in turn, can reduce the buildup of plaque in arteries, the researchers wrote.[30]
A study published in the August 22, 2006 edition of Biological Psychology looked at the modification of the stress response via L-Theanine, a chemical found in green tea. It "suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation."[31]
In a double-blind, randomized, placebo-controlled trial conducted by Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 240 adults were given either theaflavin-enriched green tea extract in form of 375 mg capsule daily or a placebo. After 12 weeks, patients in the tea extract group had significantly less low-density lipoprotein cholesterol (LDL-C) and total cholesterol (16.4% and 11.3% lower than baseline, p<0.01) than the placebo group. The author concluded that theaflavin-enriched green tea extract can be used together with other dietary approaches to reduce LDL-C.
A study published in the January, 2005 edition of the American Journal of Clinical Nutrition concluded "Daily consumption of tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity." [32]
According to a Case Western Reserve University School of Medicine study published in the April 13 2005 issue of the Proceedings of the National Academy of Sciences, antioxidants in green tea may prevent and reduce the severity of rheumatoid arthritis. The study examined the effects of green tea polyphenols on collagen-induced arthritis in mice, which is similar to rheumatoid arthritis in humans. In each of three different study groups, the mice given the green tea polyphenols were significantly less likely to develop arthritis. Of the 18 mice that received the green tea, only eight (44 percent) developed arthritis. Among the 18 mice that did not receive the green tea, all but one (94 percent) developed arthritis. In addition, researchers noted that the eight arthritic mice that received the green tea polyphenols developed less severe forms of arthritis.
A German study found that an extract of green tea and hot water (filtered), applied externally to the skin for 10 minutes, three times a day could help people with skin damaged from radiation therapy (after 16–22 days).[33]
A study published in the December 1999 American Journal of Clinical Nutrition found that "Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both."[34]
In lab tests, EGCG, found in green tea, was found to prevent HIV from attacking T-Cells. However, it is not yet known if this has any effect on humans.[35]
A study in the August, 2003 issue of a new potential application of Cellular and Molecular Life Sciences found that "a new potential application of (–)-epigallocatechin-3-gallate [a component of green tea] in prevention or treatment of inflammatory processes is suggested" [36]
However, pharmacological and toxicological evidence does indicate that green tea polyphenols can in fact cause oxidative stress and liver toxicity in vivo at certain concentrations.[37] This would imply that consumers should exercise caution when consuming herbal products produced from concentrated green tea extract. Other evidence presented in the review cautions against the drinking of green tea by pregnant women.[38]
A more frequent consumption of green tea was associated with a lower prevalence of depressive symptoms in a Japanese study [39]. Researchers conducted a cross-sectional study in 1,058 community-dwelling elderly Japanese individuals 70 years of age. The prevalence of mild and severe depressive symptoms was 34.1 percent and 20.2 percent, respectively. After adjustment for confounding factors, the odds ratios for mild and severe depressive symptoms when higher green tea consumption was compared with green tea consumption of 1 cup/d were: 2 to 3 cups green tea/d and 4 cups green tea/d. Similar relations were also observed in the case of severe depressive symptoms.
Drug Interactions
A 2009 study at the University of Southern California using mouse models showed that several of the polyphenolic ingredients of green tea, such as EGCG, can bind with the anticancer drug bortezomib, significantly reducing its bioavailability and thereby rendering it therapeutically useless.[40] This chemical reaction between EGCG and bortezomib is highly specific and depends on the presence of a boronic acid functional group in the bortezomib molecule. Dr. Schönthal, who headed the study, suggests that consumption of green tea, concentrated green tea extract, and other green tea products (such as EGCG capsules) be strongly contraindicated for patients undergoing bortezomib treatment.[41]
Caffeine
Unless specifically decaffeinated, green tea contains caffeine.[42] Normal green tea itself may contain more caffeine than coffee (by dry weight--for caffeine per serving size, see below), but the length of infusion with hot water and the number of times the leaves are reused can greatly alter caffeine intake.[42] Using a given amount of green tea leaves steeped in 100 mL of water, experiments have shown that after the first 5 minutes of brewing, the tea contains 32 mg caffeine.[42] But if the same leaves are then used for a second and then a third five minute brew, the caffeine drops to 12 mg and then 4 mg, respectively.[42]
While coffee and tea are both sources of caffeine, the amounts of caffeine in any single serving of these beverages varies significantly. An average serving of coffee contains the most caffeine, the same serving size of tea provides 1/2 to 1/3 as much.[43] One of the more confusing aspects of caffeine content is the fact that coffee contains less caffeine than tea when measured in its dry form. The caffeine content of a prepared cup of coffee is significantly higher than the caffeine content of a prepared cup of tea.[44]
Green teas contain two caffeine metabolites (caffeine-like substances): theophylline, which is a stronger stimulant than caffeine, and theobromine, which is slightly weaker than caffeine.
Safety
Main article: Epigallocatechin gallate#Drug Interactions
In 2008 the US Pharmacopeia reviewed the safety of green tea extract. It found 216 case reports, 34 on liver damage, of which 27 were categorized as possible and 7 were categorized as probable. Potential for adverse effects is increased when extracts are used, particularly on an empty stomach.[45]
White tea health information from Wikipedia
Health benefits
Main article: Health effects of white tea
A 2009 Kingston University study showed that white tea had high anti-inflammatory, anti-oxidant, anti-collagenase, and anti-elastase properties which could potentially reduce the risks of developing rheumatoid arthritis, some cancers, heart disease & slow the enzymatic break down of elastin and collagen (ie wrinkles or sagging) which accompany aging. [3]
White tea compared to green tea
A study at Pace University in 2004 showed white tea had more anti-viral and anti-bacterial qualities than green tea.[4]
White tea contains similar concentrations of catechins to green tea, although the concentration of specific oxidation products differs slightly due to its lack of processing.[5] Furthermore, one study examining the composition of brewed green and white teas found that white tea contained more gallic acid and theobromine.[6]
As white tea is made out of young leaves and buds, it has more of amino acid theanine (has relaxing and mood enhancing properties) than green and black teas which are made from older leaves.
Caffeine content of green and white teas are similar, though both depend on factors such as the variety of tea, the cut and length of the leaf, and the method of steeping.
White tea is thought to contain less fluoride than green tea, since it is made from young leaves only, but both white and green teas use young leaves, and bai mu dan white tea uses the more mature leaves as well.[5]
Sources
wikipedia.org/wiki/Black_tea#Health_and_nutrition
wikipedia.org/wiki/Green_tea#Health_effects
wikipedia.org/wiki/White_tea#Health_benefits
