Tea: Is It Time for a Tea Party?
Some animal studies have shown hope regarding the potential health benefits of tea. Yet others show little effect on health.
Possible benefits of tea
Different teas: The question of green tea vs black tea is one of great debate. Green tea is made from unfermented leaves, and black tea is made from fermented leaves of the same plant. Oolong tea and white tea also come from the same plant, but are less extensively studied.
Stroke: Some animal studies have shown that green tea might help prevent stroke.
Cancer: Animal studies and cell studies have shown that extracts of green tea and tea polyphenols might help prevent the development and growth of many forms of cancer. Unfortunately, epidemiological studies are much less hopeful. Green tea does not seem to help prevent prostate cancer unless the man has, or is at high risk for, the disease. Cohort studies have not shown any effect on consumption of green tea and risk for developing breast cancer for most women. However, like prostate cancer, green tea might benefit women who already are diagnosed with breast cancer. In general, it seems more likely that green tea is attributed more than other types of tea with the prevention of cancer and recurrence of cancer.
Weight loss: Contrary to popular belief, the catechin epigallocatechin gallate (EGCG) does not seem to aid weight-loss efforts. Some evidence shows that the polyphenol content of tea can increase endurance during exercise because of improved fat metabolism.
Memory: It does appear hopeful that either green or black tea may help to slow the memory decline that occurs with aging. In one large study, it appears that people who drank either kind of tea at least five times a week had roughly a 30% slower rate of decline on annual Mini-Mental State Examinations than those who did not consume any tea.
Cardiovascular disease: The study of tea in relation to cardiovascular disease remains inconclusive regarding catechin effects on lipid levels, blood pressure, and coronary artery disease. The US Food and Drug Administration has deemed the evidence regarding green tea and heart health as 'supportive, but not conclusive.'
Diabetes: Findings on diabetes and tea also are inconclusive, and the evidence seems even less convincing as more studies are completed.
Osteoporosis: Black tea may prevent osteoporosis.
Tooth decay: Both black and green teas seem to inhibit bacteria that cause tooth decay.
Parkinson's disease: A study published in the April 2011 issue of Parkinsonism & Related Disorders found that coffee, black tea, Japanese tea, and Chinese tea all decreased the risk of Parkinson's disease.
Immune function and autoimmune disease: On June 2, 2011, Oregon State University announced the finding that green tea increases the number of regulatory T cells that play a key role in immune function and suppression of autoimmune disease. The findings were published in Immunology Letters. Scientists noted that EGCG effects were 'not as potent as some of those produced by prescription drugs, but it also had few concerns about long-term use or toxicity.'
The terminology of tea
Polyphenols: These are chemicals found in many foods, including tea. They are antioxidants.
Oxygen radical absorbance capacity (ORAC) score: ORAC is a measure of antioxidants. Tea ranks as well as many fruits and vegetables on the ORAC score.
Flavonoids: These polyphenols may have anti-inflammatory and anticarcinogenic properties.
Catechins: These are a form of flavonoids.
EGCG: EGCG is the catechin most present in tea and the catechin most studied for health benefits. EGCG is not fully absorbed by the body and is not 'readily available' to the body.
A bottle of a popular tea beverage is not likely to do much for you. The content of actual tea in these drinks is so minor, actually negligible. If the ingredient list says 'tea extracts' or 'tea concentrate,' you might as well skip it. A 16-oz bottle probably contains fewer polyphenols than 1 cup of brewed tea. If you want to try tea, go for the freshly brewed form.
It is not known whether decaffeinated teas have the same polyphenols or level of polyphenols as traditional brews.
Milk in tea
Originally, it was thought that milk blocked the absorption of catechins. It is now known that it does not, unless you plan to make your tea with milk and then let it sit for 1 hour or longer before drinking it.
The bottom line
It is hard to say whether it is the tea itself that improves health or whether it is something else that happens to correlate with people who tend to drink more tea. For instance, do the people who drink the most tea also exercise the most or eat the most vegetables? More research is needed to know for sure, but it looks as though you will likely have to drink several cups of tea each day to aid your health. However, tea is unlikely to hurt you, so you might as well drink it for the potential health benefits.