Highlights

highlights

Essential Nutrients for a Naturally Healthy Body

  • Research suggests that antioxidants can be beneficial to health by helping the body protect itself from the harmful effects of "free radicals".
  • Studies provide evidence that tea contains protective antioxidants that can help body protect itself against free radicals, molecules that can damage cells.
  • Unsweetened, fresh tea is sodium-free, sugar-free, fat-free, virtually calorie-free and a satisfying, aromatic beverage. It's an ideal choice for a healthy lifestyle or weight-loss, especially when substituting for other sugar sweetened beverages.
  • In a study comparing tea and coffee showed that tea produced more consistent levels during the day and appeared to have a more gentle reviving effect. Green tea has about half the caffeine as a comparable cup of regular brewed coffee. Together with other research conducted on caffeine and sleep, these studies suggest that tea provides the potential beneficial effects of caffeine on performance during the day without disrupting sleep at night.

If you are interested in understanding in detail the benefits of green tea in relation to specific body functions and in comparison with other beverages, please download the White paper prepared by our experts. If you need any additional information, you are welcome to email us your questions and our experts will be happy to answer them for you.

Green Tea Studies

Introduction

According to Chinese legend, in 2737 B.C., Chinese Emperor Shen Nung sat next to a small cauldron of boiling water. Suddenly, he smelled a wonderful smell and found that leaves from the flowering camellia tree, Camellia sinensis, had fallen in the water. He sipped the water and discovered tea, which more than 4,000 years later, is the world’s second most popular drink. Over the past few decades, scientists have taken a closer look at the potential health benefits of tea.

Tea Antioxidants

Many of the health benefits of drinking tea come from the fact that tea contains high levels of antioxidants called polyphenols or flavonoids. These compounds are most prevalent in green and white teas, but are also present to varying degree in Oolong and black teas. Polyphenols can help the body protect itself against free radicals, molecules which occur in the environment and are naturally produced by the body, can cause damage to cells. Chronic damage by free radicals is one factor thought to contribute to the development of many chronic diseases including heart disease or cancer. Polyphenols scavenge cell-damaging free radicals, which are linked with cancer-causing genes and cause LDL cholesterol to form artery-clogging plaque. The polyphenols in tea possess 25 to 100 times the antioxidant potency of vitamins C and E. Antioxidants impair the ability of free radical cells to harm the molecules that make up our bodies.

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Tea & Weight Loss

Green tea has recently become the latest weapon in the war on weight. The results of some new studies are promising, finding that green tea can increase the rate of calorie burning, reduce body fat levels and even prevent excess weight gain. A human study showed that taking in the equivalent of 3 cups of green tea per day burned an additional 80 calories per day.

In a study of energy expenditure in men, those who took green tea extract containing EGCG plus caffeine three times daily burned about 80 more calories per day than those who didn't take the extract. Interestingly, taking caffeine with EGCG didn't have the same effect. Also, green tea extract was found to significantly increase 24 hour energy expenditure and fat oxidation in healthy men.

In another study, after three months of consumption of green tea extract by moderately obese patients, body weight decreased by 4.6 percent and waist circumference decreased by 4.48 percent. Researchers looked at group of flavonoids in tea and its effect on weight loss and body fat. They found significant weight loss and a significant reduction in total body fat in the people drinking tea flavonoids (equal to 3-4 cups of tea per day) when compared to participants drinking the placebo.

Green tea is believed to help prevent obesity by revving up the fat-burning effects of brown fat, sending glucose to muscle tissue where it’s more likely to be burned, rather than to fat tissue, and inhibiting the action of fat-digesting enzymes so the fat that you eat is less available to the body. Additionally, green tea is a satisfying, calorie-free beverage that can be substituted for sweetened beverages and is a delicious alternative to plain water in a healthy weight management plan.

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Tea & Heart Health

Heart disease is a major cause of preventable disease and death in all regions of the world. In US, over 40% of all deaths are caused by heart disease which affects over 64 million people, almost one quarter of the US population. As part of a healthy lifestyle regular tea drinking may help maintain a healthy heart. Green tea is associated with a reduction in many risk factors for cardiovascular disease. Besides improving cholesterol values, it may help lower blood pressure, decrease blood stickiness, and prevent LDL oxidation (a crucial beginning step in the atherosclerotic process).

Human population studies have found that people who regularly consume three or more cups of tea per day have a reduced risk of heart disease and stroke. Three separate analyses of research showed that drinking three cups of tea daily reduced the risk for cardiovascular disease death or heart attack by about 10-12%. Clinical studies suggest that the risk reduction associated with tea consumption may be due to improvement in some risk factors for cardiovascular disease, including cholesterol levels, blood vessel function and a reduction in oxidative damage.

While researchers are still examining the various mechanisms by which tea flavonoids function, some studies suggest multifunctional mechanisms, meaning that several mechanisms work in tandem to collectively improve markers for cardiovascular health. Important areas of tea and cardiovascular health research include blood vessel and endothelial function, or the ability of the blood vessels to dilate to allow for proper blood flow, serum cholesterol levels and Low Density Lipoprotein (LDL) cholesterol oxidation. Each of these factors impacts the risk of heart attacks, stroke and cardiovascular disease. Study findings in the area of tea and the reduction in cardiovascular disease risk include the following:

Coronary Heart Disease (CHD)

  • A total of 3,430 patients aged 30-70 years were examined and 6.3 percent were found to have indications of CHD. The study found that those who drank more than six cups of tea per day had significantly lower prevalence of CHD than non-tea drinkers, even after adjustment for risk factors like age and smoking. The study also found that drinking six or more cups of black tea per day was associated with decreased serum cholesterol and triglyceride concentrations.
  • Dutch study found that participants who drank one to two cups of black tea daily had a 46 percent lower risk of severe aortic atherosclerosis, a strong indicator of cardiovascular disease. Those who drank more than four cups of tea a day had a 69 percent lower risk.

Cardiac Events

  • The Zutphen study with 805 male subjects over a period of five years, found that the incidence of fatal and nonfatal first myocardial infarction and mortality from stroke decreased significantly as intake of tea flavonoids, and the effectiveness increased in a dose-dependent manner. A follow-up study found that high intake of flavonoids significantly lowered the risk of stroke.
  • A Harvard study examined 340 men and women who had suffered heart attacks in comparison to the control subjects. They found that those who drank a cup or more of black tea daily had a 44 percent reduction in the risk of heart attack compared to non-tea drinkers.
  • Another recent Harvard study of 1,900 people found that those who consumed tea during the year prior to a heart attack were up to 44 percent more likely to survive over the three to four years following the event. Those who consumed about 14 cups of tea per week experienced a 28 percent reduced death rate and those who consumed more than 14 cups of tea per week were found to have a 44 percent reduced death rate, as compared to non-tea drinkers.

Cholesterol

Researchers believe that green tea helps reduce cholesterol by lowering its absorption in the digestive tract and increasing its excretion. A study conducted by United States Department of Agriculture (USDA) showed that the effect of tea on 15 mildly hypercholesterolemic patients following a "Step I" type diet moderately low in fat and cholesterol. After three weeks, the patients with five servings of black tea per day reduced LDL ("bad") cholesterol by 11.1 percent and total cholesterol (TC) by 6.5 percent compared to placebo beverages.

Italian researchers studying two groups of volunteers following a controlled diet found that those who drank two cups of green tea (about 250 mg of catechins) per day for 6 weeks reduced their LDL "bad" cholesterol by an average of 13 mg/dl.

A double blind, randomized, placebo-controlled study involving 240 people with mildly to moderately-elevated cholesterol found that taking 375 mg of theaflavin-enriched green tea extract daily for 12 weeks caused a reduction in total cholesterol of 11.3% and in LDL cholesterol of 16.4%, while the HDL "good" cholesterol increased by 2.3%.

Animal studies have shown that even when consuming a diet rich in lard and cholesterol, rats who receive green tea catechins have much lower cholesterol levels than those who don't receive the catechins.

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Tea & Cancer Prevention

Research studies suggest that the flavonoids in tea could play a role in human cancer risk reduction possibly by combating free radical damage, inhibiting uncontrolled cell growth (cell proliferation), and by promoting programmed cell death (apoptosis). Leading scientists worldwide are actively studying these potential mechanisms, and clinical trials and population studies are underway. More evidence is needed before any definitive conclusions can be drawn. Recent findings include:

  • A recent study found that smokers who drank four cups of green tea per day demonstrated a 31 percent decrease in biomarkers of oxidative DNA damage in white blood cells as compared to those who drank four cups of water. Oxidative DNA damage is implicated in the development of various forms of cancer.
  • Epigallocatechin gallate (EGCG) may protect normal cells from cancer-causing hazards as well as eliminate cancer cells though apoptosis. Researchers tested the potential anti-cancer benefits of a green tea polyphenol, EGCG, in hamster cells and discovered that EGCG suppressed DNA changes and damage from carcinogens. EGCG also protected from further damage from the carcinogens and inhibited growth and multiplication of cancer cells.

Rectal/Colon Cancers

  • An epidemiological study conducted by the University of North Carolina found consumption of the equivalent of 2.5 cups of tea per day or more was associated with a 60 percent drop in rectal cancer risk among Russian women from Moscow, as compared to women who drank relatively less than 1.2 cups of tea per day. Those women who drank approximately 1.2 to 2.5 cups of tea per day had a 52 percent reduction in the risk of rectal cancer.
  • Based on data from the NHANES I Follow-Up study (NHEFS), researchers found that tea drinkers had about a 42 percent reduced risk of colon cancer as compared to non-tea drinkers. Men who drank more than 1.5 cups of tea per day were found to have a 70 percent lower colon cancer risk.
  • Researchers who followed a group of over 34,000 postmenopausal healthy women between 55 - 69 years of age for 12 years found that those consuming high levels of catechins experienced up to a 45 percent decrease in the instances of rectal cancer. Catechins are a class of flavonoids found in tea, fruits and vegetables. Catechins derived from tea were most strongly linked to a decrease in rectal cancer.
  • The Iowa Women's Study, which followed post-menopausal women between the ages of 55 and 69 for eight years, found that participants who drank two or more cups of tea per day had a 32 and 60 percent reduced risk of developing digestive and urinary tract cancers, respectively.
  • A large population study found an inverse relationship between green tea consumption and the risk of colon, rectal and pancreatic cancer. Male participants, who drank 4.5 servings of tea per day, had an 18 percent decrease in colon cancer risk and 28 percent decreased risk of rectal cancer. Female participants, who drank 3 servings of tea per day, were observed to have a decreased risk of colon and rectal cancer by 33 percent and 43 percent, respectively. Risk of pancreatic cancer was also reduced in both men and women by 37 percent and 47 percent respectively.

Stomach Cancers

  • Researchers from Shanghai, China compared 206 people newly diagnosed with stomach cancer to 415 healthy control subjects. After studying the volunteers’ health, diet and lifestyle habits, the researchers concluded that drinking green tea reduced the risk of developing stomach cancer by as much as 41%.
  • A study conducted with members of the Shanghai Cohort (18,244 men aged 45-64 years at recruitment with up to 12 years of follow-up) discovered a statistically significant inverse relationship between positive tea polyphenols levels (as measured in urine) and gastric cancer.

Lung Cancers

  • The diet and lifestyle habits of 649 nine women with lung cancer were compared to those of 675 healthy women. The researchers found that drinking green tea reduced the risk of developing cancer by as much as 35% (in the nonsmokers only), and that the more green tea consumed, the greater the protection.

Breast Cancers

  • A study of 1,100 Asian-American women, half of whom had breast cancer, showed that those in the non-cancer group were much more likely to be green tea drinkers. The researchers concluded that "green tea drinkers showed a significantly reduced risk of breast cancer..." and the more green tea consumed, the greater the protection.
  • The combined results four studies (a meta-analysis) showed a 12% reduction in risk of developing breast cancer for those drinking the most green tea compared to those drinking the least.

Pancreatic Cancers

  • A case-control study of cancer of the pancreas involving over 200 people found a significantly decreased risk of developing the disease in those who consumed green tea.
  • Another study found that those who drank 2 or more cups of green tea per day had a 60% lower risk of developing pancreatic cancer. In test-tube studies, green tea has been shown to fight pancreatic cancer by damaging the mitochondria of the cancer cells and inhibiting cancer activation.

Prostate Cancers

  • A double-blind, placebo-controlled study of green tea’s ability to fight prostate cancer was published in Cancer Research in 2006. Sixty men with HG-PIN, a condition that can quickly progress to prostate cancer, were divided into two groups. One group received 600 mg of green tea catechins per day; the other did not. After one year, only one prostate tumor was found among the green tea group compared to 9 in the control group.

Oral Cancer

  • A human intervention trial the effect of treating superficial precancerous lesions (leukoplakia) in the mucosal lining of the mouth with a mixed tea product. After the six-month trial, partial regression of the lesions was observed in 37.9 percent of the group treated with tea as compared to only 10 percent of those treated with a placebo.
  • Researchers examined the effects of tea and curcumin, a spice and food-coloring agent, on oral cancer in hamsters. Hamsters were treated with a cancer-causing solution topically inside the cheek three times a week for six weeks. Two days after the last treatment of the solution, the hamsters were given Green Tea as drinking fluid or curcumin applied topically three times per week, the combination of Green Tea and curcumin treatment, or no treatment for 18 weeks. At the end of this period, the scientists observed that the combination of tea and curcumin significantly decreased the number of visible tumors and tumor volume. Furthermore, tea alone and in combination with curcumin increased cancer cell death, or apoptosis.

Ovarian Cancer

  • A case-control study conducted in China, which employed 254 patients with histologically confirmed epithelial ovarian cancer and 652 control subjects, determined green tea consumption based on a validated questionnaire and found that, after accounting for demographic, lifestyle and familial factors, ovarian cancer risk declined with increasing frequency and duration of overall tea consumption.

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Tea & Immune Function

A healthy immune system protects the body from infection and disease. The researchers identified a substance in tea, L-theanine – a unique amino acid, which primes the immune system in fighting infection, bacteria, viruses and fungi. This suggests that regular tea consumption may help support the body’s immune system. Researchers from the Brigham and Women’s Hospital and Harvard University recently published new data indicating that theanine can help the body ward off infection and disease and may strengthen the immune system.

A subsequent human clinical trial showed that certain immune cells of participants who drank five cups of black tea a day for two to four weeks secreted up to four times more interferon, an important part of the body’s immune defense, than at baseline. Consumption of the same amount of coffee for the same duration had no effect on interferon levels. According to the authors, this study suggests that drinking black tea provides the body’s immune system with natural resistance to microbial infection. While research on effects of tea on the body’s immune system and its potential to help protect the body is just emerging, experts are encouraged by these promising results.

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Tea & Oral Health

Tea may also contribute to oral health. The flavonoids in tea may inhibit the plaque-forming ability of oral bacteria and the fluoride in tea may support healthy tooth enamel. Tea is a good source of fluoride, a mineral that helps protect teeth by strengthening tooth enamel and combating cavities. Research studies indicate that tea flavonoids may inhibit the plaque-forming ability of oral bacteria. Tea does this through an anti-bacterial effect on Streptococcus bacteria, by preventing the bacteria’s adherence to teeth and by limiting of the synthesis of sticky glucan which in animal studies has been shown to help prevent cavities.

A recent study conducted at the New York University Dental Center examined the effects of black tea extract on dental caries formation in hamsters. Compared to those who were fed water with their food, hamsters which were fed water with black tea extract developed up to 63.7 percent fewer dental caries.

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Tea & Bone Health

Although high caffeine intake has been suggested to be a risk factor for reduced bone mineral density (BMD), research indicates that drinking tea does not negatively affect BMD, and while it may be too soon to state definitively, findings suggest that tea may even play a role in bone health. A study published recently in the American Journal of Clinical Nutrition found that older women who drank tea had higher BMD measurements than those who did not drink tea. The researchers concluded that the flavonoids in tea might influence bone mass and that tea drinking may reduce the risk of osteoporosis. Another recent study found that habitual tea-drinking was seen to have a significant beneficial effect on the BMD of adults (30 years and older), especially in those who had been habitual tea-drinkers for six or more years. Studies in adolescent and postmenopausal women found no relationship between caffeine intake and bone health.

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Tea & Skin Health

According to a study conducted by the University of Arizona, participants who drank iced black tea and citrus peel had a 42 percent reduced risk of skin cancer. Black tea consumption is associated with a significantly lower risk of squamous cell carcinoma (SCC), a form of skin cancer; tea concentration (strength), brewing time and temperature all influence the potential protective effects of hot black tea on SCC. Oral consumption of green or black tea decreased the number of tumors in mice following exposure to UV radiation. Green tea polyphenols may have cancer preventive potential, especially in the case of solar UV-induced cancer. Research suggests that compounds in green tea may protect skin from ultraviolet (UV) radiation-induced damage when applied topically. Topical treatment of green tea polyphenols on human skin prior to UV exposure inhibited indicators of DNA damage, thus inhibiting photocarcinogenesis, or UV-induced skin cancer. Experiments that show that administration of green tea, Black Tea or specific flavonoids in tea inhibited the growth of established nonmalignant and malignant skin tumors in tumor-bearing mice. In addition, oral administration of Black Tea inhibited DNA synthesis and enhanced cell death (apoptosis) in both nonmalignant and malignant tumors in tumor-bearing mice.

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