by Function & Organ
A Japanese priest in the 13th century wrote a lengthy treatise on the health benefits of tea stating, "Tea is a marvelous elixir of health that has the capacity to prolong human life. Most medicines treat only a single ailment, but tea is a panacea for all ills." A bold statement, but today’s research studies are now lending support to his claims. Although green and white tea has received more news media attention than black and oolong tea, all teas have their own medicinal strengths. Studies conducted around the world have shown that tea drinking might protect against such serious diseases as strokes, cancer, and heart disease, as well as boost memory, immunity, stress relief, skin health, and weight loss.
Tea protects your bones. It’s not just the milk added to tea that builds strong bones. A recent study indicates that tea may increase bone mineral density, which helps prevent fractures and osteoporosis.
In the study, published in the Archives of Internal Medicine, researchers surveyed 1037 men and women age 30 and older about their tea consumption. The researchers found that people who consumed tea regularly for more than 10 years had the highest bone mineral density (BMD) scores compared to the other groups, after they adjusted for sex, age, weight, and lifestyle variables that may affect BMD. Those who drank tea regularly for the past 6–10 years also had significantly higher lumbar spine BMDs than the non–regular tea drinkers. It didn’t seem to matter what type of tea the person drank, and neither did the amount of tea consumed each time. Only duration of habitual tea consumption was an independent predictor of BMD score. Tea contains several components, including fluoride and flavonoids, which may work separately or in concert to maintain or restore bone density.
Results of a Chinese study published in the May 2002 issue of the Archives of Internal Medicine showed that men and women who are long–time tea drinkers do seem to have an advantage in terms of bone mineral density over those who don’t habitually drink tea.
Yet another study that compared tea drinkers with non–drinkers, found that people who drank tea for 10 or more years had the strongest bones, even after adjusting for age, body weight, exercise, smoking and other risk factors.
In addition, tea has less caffeine than coffee (which can interfere with calcium absorption) and offers flavonoids and fluoride which can enhance bone strength.
Drinking tea is beneficial for your brain, protecting its cells from degeneration and helping to keep your mind sharp, scientists say.
Professor Ng Tze Pin from the National University of Singapore’s psychological medicine, who was a leading researcher of the four–year study, says any type of tea is good for maintaining brain health. Catechins, a natural compound in tea, were found to protect brain cells from the protein, that builds up over the years and undermines cognitive function. It is known that tea contains caffeine but unlike in coffee, it also contains theanine, a natural compound that reduces the side effects of the caffeine such as increased blood pressure, fatigue and headaches. Changes in brain cells, such as loss of nerve cells, genetic predisposition, minor strokes and protein that builds up with ageing may all lead to dementia, a progressive decline in cognitive capability. During the study, scientists analyzed drinking habits of 2,501 Chinese people aged from 55 and older for four years. Also the participants’ health, attention span, cognitive abilities were examined. Around 38 percent of the participants said that they did not drink tea, while 29 percent preferred one type of tea and others reported about drinking different types of tea. After a two year period, tea–drinkers showed the same results on memory tests as at the beginning of the study, while 35 percent of those who did not drink tea showed decline in cognitive tests.
White tea can create a calmer but more alert state of mind. Studies have shown that the amino acid L–theanine found in the tea plant alters the attention networks in the brain and can have demonstrable effects on the brain waves. More simply, tea can help you relax and concentrate more fully on tasks. Buddhist monks drank white tea to keep them from falling asleep during meditation.
Considerable research is being carried out on tea and its role in preventing cancer. Scientific research in both Asia and the west is providing hard evidence for the health benefits long associated with drinking tea.
In 1994 the Journal of the National Cancer Institute published the results of an epidemiological study indicating that drinking green tea reduced the risk of esophageal cancer in Chinese men and women by nearly sixty percent. University of Purdue researchers recently concluded that a compound in green tea inhibits the growth of cancer cells.
Tea helps to inhibit the onset of cancer by blocking the action of nitrosamines, which can cause cancer. Another way tea may help fight cancer is through preventing cell mutation. The antioxidative actions of the polyphenols in green tea inhibit mutation of the DNA in healthy cells, which can cause them to become cancer cells.
Research at the Mayo Clinic shows that a component in green tea helps kill cells of the most common form of leukemia. The scientists say the green tea component – EGCG – helps kill the cancer cells by cutting off the communication signals they need to survive. The findings, reported in an early electronic article in the journal Blood, show green tea's EGCG killed leukemia cells in eight of ten patient samples tested. Researchers say the green tea results are an excellent start in an effort to find agents that will kill cancer cells and are nontoxic to the patient.
Stomach cancer, the number one cause of death in Japan, is at its lowest rate in Shizuoka prefecture along the coast southwest of Tokyo. One explanation is that Shizuoka is a tea–growing district and its inhabitants drink large amounts of green tea.
A study was conducted in China during 1999–2000 [it was published in 2002] on Ovarian Cancer and green tea consumption. The researched cases were 254 patients with confirmed ovarian cancer. Controls [non–cancer afflicted persons] numbered 652 and included hospital visitors and individuals recruited from the community. The ovarian cancer risk declined with increasing frequency and duration of overall [green] tea consumption. It was 60% less risk for those drinking tea daily and about 80% less risk for those drinking tea for 30 years. The conclusion was that increasing frequency and duration of tea drinking, especially green tea, can reduce the risk of ovarian cancer.
Research shows that green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people.
One population–based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea. Results from one animal study suggest that polyphenols in green tea may block the intestinal absorption of cholesterol and promote its excretion from the body. In another small study of male smokers, researchers found that green tea significantly reduced blood levels of harmful LDL cholesterol.
For some individuals, simply limiting their intake of cholesterol does not always significantly lower their blood cholesterol level. Green tea has been shown to help decrease cholesterol. Puerh tea has been shown to help enhance fat metabolism. Both green tea and puerh teas teas bond to cholesterol, retarding absorption as it goes through the digestive tract. This means the body does not absorb the fat.
Green tea has been used traditionally to control blood sugar in the body.
Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. People with type 1 diabetes produce little or no insulin, a hormone that converts glucose (sugar), starches, and other foods into energy needed for daily life. Green tea may help regulate glucose in the body.
A few small clinical studies have found that daily supplementation of the diet with green tea lowered the hemoglobin A1c level in individuals with borderline diabetes.
Tea drinkers can take “heart”, as Tea may reduce your risk of heart attack, stroke, and hypertension.
Unwanted blood clots formed from cholesterol and blood platelets cause heart attack and stroke. Drinking tea may help keep your arteries smooth and clog–free, the same way a drain keeps your bathroom pipes clear. People who drink tea each day significantly reduce their chances of atherosclerosis, or hardening of the arteries, according to a study published in the Archives of Internal Medicine. Those who drank one or two cups a day lowered their risk by 46 percent. For those who drank four cups a day, the risk dropped by 69 percent. The beneficial effects of tea are presumed to be due to the bioflavanoids, natural substances that act as powerful antioxidants, limiting the effects of free radicals in the body.
Drinking tea on a regular basis may help protect patients with existing cardiovascular disease, according to a study in the May 7 issue of Circulation: Journal of the American Heart Association, which finds that tea consumption is associated with an increased rate of survival following a heart attack. Kenneth Mukamal, MD, MPH, and his co–authors found that among individuals who had suffered heart attacks, those who reported being heavy tea drinkers (14 or more cups per week) had a 44 percent lower death rate than non–tea drinkers (fewer than 14 cups per week) in the three–and–a–half years following their heart attacks, while moderate tea drinkers had a 28 percent lower rate of dying when compared with non–tea drinkers. "It’s pretty clear that flavonoids can prevent LDL [low density lipoprotein] cholesterol from becoming oxidized," Mukamal says, explaining that oxidized LDL can lead to the development of atherosclerosis. In addition, a recent study found that drinking black tea improved endothelial function – the ability of the blood vessels to relax – in cardiac patients. Finally, he adds, flavonoids may have an anti–clotting effect. "What was surprising was the magnitude of the association," says Mukamal. "The heaviest tea drinkers had a significantly lower mortality rate than non tea–drinkers."
Research shows substantial decreased risks of hypertension with daily tea consumption.
A Taiwanese study done in 2004 found that people who drank tea regularly had lower blood pressure than those who did not. In Taiwan, the habitual tea drinkers among the randomly chosen sample of 1500 healthy men and women tended to be fatter and more likely to smoke, drink alcohol and consume salt, and were less likely to eat vegetables.
Nevertheless, blood pressure measurements were lower among the tea drinkers. The researchers calculated that the odds of developing hypertension were cut almost in half among those who drank one small cup a day, and by about two–thirds among those who drank 20 ounces or more daily. There was no difference between those who drank green and black tea.
Many studies have demonstrated that intense or prolonged exercise generates considerable amounts of reactive oxygen species (oxidants) within the human body. These reactive oxygen species can produce oxidative stress, like damage to fats, proteins, nucleic acids and – ultimately – muscle cells.
Such oxidative stress has naturally been linked with fatigue and overtraining, and it has been suggested that the human body’s natural oxidant–defense system is not powerful enough to prevent the oxidative stress associated with rugged exercise. Thus, the argument goes, athletes need to accelerate their intakes of foods which are rich in antioxidants. Tea would thus be a sought–after beverage, since it may rank ahead of all others in terms of antioxidant potency. Observers of the athletic scene sometimes wonder if it is more than a coincidence that the best endurance athletes in the world – the Kenyan runners – sip tea throughout the day.
So is tea a near–perfect sports drink? If a couple of cups of tea are consumed about an hour before exercise, the caffeine content is likely to enhance performance in high–intensity athletic events. When tea is consumed post–exercise, its rich antioxidant content may well boost recovery and limit oxidative stress to muscles. If you add generous amounts of milk (either soy or cow) and sugar to the tea (as the Kenyans do), it can stimulate protein synthesis and glycogen storage in muscles.
It’s true that more research is needed in this area, but our present state of knowledge suggests that green, oolong, and black varieties of are an attractive drink for both endurance and sprint athletes.
Tea is one of the top ranked foods and drinks that can boost your immune defenses.
The powerful antioxidants it contains may help prevent heart disease, cancer and may also protect against aging. Antioxidants are essential for good health. They deal with free radicals in our body. Green tea contains more antioxidants per part than vegetables and fruits making it a terrific food for our immune system. Polyphenols attack free radicals. Free radicals can accelerate aging and damage your DNA. Green tea is a wonderful resource for polyphenols and is a food that will give your immune system a powerful charge.
A new study finds that tea boosts the body’s defenses against infection and contains a substance that might be turned into a drug to protect against disease. Tea was found in laboratory experiments to prime the immune system to attack invading bacteria, viruses and fungi, according to a study in the Proceedings of the National Academy of Sciences. A second experiment, using human volunteers, showed that immune system blood cells from tea drinkers responded five times faster to germs than did the blood cells of coffee drinkers. “We worked out the molecular aspects of this tea component in the test tube and then tested it on a small number of people to see if it actually worked in human beings,” said Dr. Jack F. Bukowski, a researcher at Brigham and Women’s Hospital in Boston and Harvard Medical School. The results, he said, gave clear proof that five cups of tea a day sharpened the body’s disease defenses.
White tea is frequently found in skin care products to help keep your skin blemish–free.
The antioxidants in white and green tea may have an effect on acne, and in some cases have been shown to work as well as a 4% solution of the much more harsh benzoyl peroxide. White tea is widely used in beauty and cosmetic products, with the promise that its high antioxidant content will keep your skin looking young.
More generally speaking, tea is an inhibitor of skin disorders. The polyphenol in tea mainly responsible for the prevention of cancer formation is epigallocatechin–3–gallate(EGCG). When applied to skin, EGCG prevents UVB–induced oxidative stress and suppression of the immune system. Many cosmetic and pharmaceutical companies are now supplementing their skin care products with green and white tea.
Tea drinkers may respond to stress better than non tea drinkers, showing decreased levels of cortisol in their blood following stressful events.
Daily cups of tea can help you recover more quickly from the stresses of everyday life by affecting levels of the stress hormone cortisol, a new British study shows. Published in the international journal Psychopharmacology, the study found that people who drank tea were able to de–stress more quickly than those who drank a tea substitute. Following a stressful event, tea–drinkers also had lower levels of cortisol in their blood when compared with a control group who drank placebo tea. "Drinking tea has traditionally been associated with stress relief," said co–author Andrew Steptoe, of the Department of Epidemiology and Public Health at University College London. Until now, however, scientific evidence for the relaxing properties of tea has been quite limited, he said.
Stress hormone (cortisol) levels dropped by an average of 47 per cent in the tea drinking group compared with 27 per cent in the fake tea group, following a stressful event. UCL researchers also found that blood platelet activation – linked to blood clotting and the risk of heart attacks – was lower in the tea drinkers, and that this group reported a greater degree of relaxation in the recovery period after the task.
"We do not know what ingredients of tea were responsible for these effects on stress recovery and relaxation," said Steptoe. "Nevertheless, our study suggests that drinking black tea may speed up our recovery from the daily stresses in life. This has important health implications, because slow recovery following acute stress has been associated with a greater risk of chronic illnesses such as coronary heart disease."
Tea has long been used as an aid for weight loss. Drinking a cup of tea with each meal is protocol for using tea successfully as a metabolic stimulant.
Tea by itself carries no fat or calories, and it’s most healthy when consumed with nothing added. The caffeine in tea increases body function to help burn more calories and the polyphenols seem to aid in the digestion of fat, making it an effective beverage to supplement weight–loss regimens. Puerh and oolong teas have received the most attention regarding weight loss, but all types of tea offer a zero–calorie alternative to commercial beverages.