Tea in all its true forms improves the overall health of an individual, find recent studies.
All true tea (white, green, oolong and black, as opposed to herbal varieties) comes from one plant: Camellia sinensis.
The differences are in how they are processed, with white and green being the least processed, oolong in the middle and black the most processed.
The processing changes the nutritional profile and some of the health effects. But no matter the process, all tealeaves are dense with flavonoids, health-promoting chemicals found in fruits, vegetables, whole grains and most plants, said researchers.
"About one-third of the weight of a tea leaf is flavonoids, which is high, especially when you consider there are virtually no calories," the Stuff.co.nz quoted Jeffrey Blumberg, professor of nutrition science and policy at Tufts University and chairman of the tea symposium, as saying.
"A serving of tea is like adding a serving of fruits or vegetables to your diet," he added.
Tea helps your heart by keeping blood vessels unclogged and flexible. Blood pressure and stroke risk were reduced in epidemiological and clinical studies (even with sugar added).
In a double-blind, randomised study in which hypertensive men drank one cup of black tea daily, both systolic and diastolic blood pressure were reduced.
The blood-pressure-lowering effect was maintained even after a large intake of fatty, sugary food, which usually constricts blood vessels, showing that "cardiovascular protection can be achieved even without much sacrifice and with normal intakes," said Claudio Ferri, a professor at Italy's University of L'Aquila School of Internal Medicine and co-author of the study.
Healthier blood vessels create better blood flow, which means all of your organs, including the brain, are receiving more blood, oxygen and nutrients, enhancing your body's ability to fight disease. So, healthier blood vessel linings might be one reason why tea consumption seems associated with so many benefits.
It improves bone health. After drinking four to six cups of green tea daily for six months, post-menopausal women with low bone mass (osteopenia) achieved an improvement in certain short-term measures of bone health in a National Institutes of Health-funded study conducted at Texas Tech University Health Sciences Center.
They also improved muscular strength. Tea reduced oxidative stress and inflammation, preventing the usual bone and muscle breakdown.
It can help your thinking. When your brain receives better blood flow and oxygen, and inflammation and oxidative stress are reduced, there is improved cognitive function, according to studies.
In fact, a 25 percent reduction in impairments of activities of daily living was found when adults drank three to four cups of tea daily.
It might reduce cancer risk. Many animal and test-tube studies have found anti-cancer effects of tea, but human studies have been less consistent.
"In lab studies, compounds in tea show a lot of cancer fighting promise. Many act as antioxidants, slow tumour growth and even increase cancer cell death," said Alice Bender of the American Institute for Cancer Research.
"But the evidence is too limited and inconsistent to make any conclusions about tea and cancer risk for humans," she noted.
It can help you lose weight. Not only does tea have fewer calories than most beverages (zero without milk and sugar), but certain compounds in tea, and especially green tea, have been found to burn body fat.
Caffeine slightly increases fat-burning, but recent studies show "the combination of caffeine and green tea catechins [tea's antioxidants] is even more effective at increasing energy expenditure and fat oxidation, though the effect is small, burning 100 calories over 24 hours, or a loss of 1.27kgs over 12 weeks," said Rick Hursel of Maastricht University, co-author of one study.
It can help you de-stress. An amino acid called L-theanine, in combination with caffeine, might reduce stress. Several studies have shown that this combination, which occurs naturally in tea, reduces cortisol, the stress hormone, while improving mental alertness.
"Tea consumption can positively affect mood and may improve creative problem solving, as compared to water," said Suzanne Einother, a Dutch researcher from Unilever (maker of Lipton tea), at the symposium.