Although tea drinking has been associated with health benefits for centuries, only in recent years have its medicinal properties been investigated scientifically. Research shows holistic benefits from green tea consumption, including lower blood pressure, dementia, oxidative stress, and chronic inflammation.
Tea’s health benefits are largely due to its high content of flavonoids — plant-derived compounds that are antioxidants. Green tea is the best food source of a group called catechins. In test tubes, catechins are more powerful than vitamins C and E in halting oxidative damage to cells and appear to have other disease-fighting properties.
Studies have found an association between consuming green tea and a reduced risk for several cancers, including, skin, breast, lung, colon, esophageal, and bladder. Green tea polyphenols act on molecular pathways to shut down the production and spread of tumor cells. They also discourage the growth of the blood vessels that feed the tumors. Green tea even acts as an antiangiogenic and antitumor agent, and helps modulate tumor cell response to chemotherapy.
Green tea, like black tea, improves both blood flow and the ability of arteries to relax. The antioxidants in green, black, and oolong teas can help block the oxidation of LDL (bad) cholesterol, increase HDL (good) cholesterol and improve artery function.
There is some evidence that long-term consumption of green tea catechins is beneficial for burning fat and may work with other chemicals to increase levels of fat oxidation and thermogenesis, and thereby help you lose weight.
Green tea can benefit your mental health to a certain degree. Specifically, its L-theanine content can relax your mind and make you alert without inducing drowsiness.
Theanine increases levels of gamma-aminobutyric acid (GABA), serotonin, dopamine, and alpha wave activity, and may reduce mental and physical stress and produce feelings of relaxation. Theanine may also help to prevent age-related memory decline and has been shown to affect areas of your brain involved in attention and complex problem-solving.
A United Kingdom lab study suggests black and green tea may slow the progression of Alzheimer’s disease. A German lab study suggests green tea may inhibit the inflammation and neural damage associated with the progression of multiple sclerosis.
By mobilizing your fatty acids, the caffeine content in green tea can be a clean, healthy source of energy compared to popular sports drinks. A study tested this hypothesis by having participants drink a caffeine drink an hour before cycling until reaching exhaustion. Compared to the group who took a decaffeinated drink, they lasted longer and also noted that the exercise was easier to perform.
Compounds in green tea rev up the immune system and may protect against certain diseases, including arthritis. “Tea drinking boosts T cells’ ability to react against bacterial and viral infections,” says Jack F. Bukowski, MD, PhD, a rheumatologist at Brigham and Women’s Hospital in Boston. This action helps your body fight off colds and flu. “I suspect this is good for people with rheumatoid arthritis, who are taking immunosuppressive medications that make them more susceptible to infection,” he says.
Studies show that tea may have anti-inflammatory properties. In lab studies, Case Western Reserve University researchers in Cleveland showed EGCG (a substance in green tea) may halt arthritis progression by blocking interleukin-1, a pro-inflammatory cell, from damaging cartilage.