What's a popular, delicious, evidence-backed beverage (especially this time of year!) that can improve your health and even play a role in chronic disease prevention? Tea is gaining much more attention for its rich antioxidant content and anti-inflammatory properties. Tea originates from the Camelia sinensis plant. Depending on how long a tea has been exposed to air, different types of tea are formed. White tea is an unoxidized tea. Green tea is made from green tea leaves before oxidation begins. Oolong tea is partially exposed to air. Black tea leaves are completely oxidized.
How Tea Works
In addition to antioxidant and anti-inflammatory effects, tea can have anti-hypertensive, anti-microbial, brain-protective, anti-cancer, and cholesterol-lowering effects. Most of these effects can be attributed to flavonoids (especially catechins), a powerful group of antioxidants that can reduce damage caused by free radicals. Tea's health properties also come from its mineral content - zinc, copper, magnesium, manganese, phosphorus, potassium, and even calcium.
Interestingly, many of tea's powerful bioactive chemicals are significantly reduced when teas are processed to be decaffeinated or used to make ready-to-drink green teas. In other words, regular freshly brewed tea is best! As with most foods, processing tea drastically lowers its nutritional benefit (not to mention how any added sugars will outdo any benefits from the tea).
Consider some of the many benefits of tea:
Anti-oxidant - To illustrate the antioxidative potential of tea, consider the results of a study done on heavy smokers. For 4 months, they consumed 4 cups of green tea, black tea, or water each day. Only green tea reduced levels of urinary 8-hydroxydeoxyguanosine - a marker of free radical damage to DNA. Researchers noted that these results suggest regular green tea consumption might even protect smokers from oxidative stress and can reduce cancer risk or risk of other diseases linked with smoking. Clearly, antioxidants in tea are effective.
Cardiovascular health - Tea can improve blood vessel function and help prevent hardening of the arteries. It can even reduce the risk of developing high blood pressure. Studies have shown how tea drinking is associated with lower cholesterol levels, and lower risk of heart attack compared to non-tea drinkers.
Anti-obesity - Tea can aid weight loss efforts by increasing energy expenditure (due to its caffeine and catechin content) and by burning fat. In fact, in one study, patients supplemented with green tea catechins and caffeine showed a 4.5% reduction in their waist size.
Oral Health - green tea has a direct anti-microbial effect on Streptococus mutans, the main bacteria responsible for dental caries. Green tea also prevents bacteria from attaching to oral surfaces.
Bottom line? Drinking at least two cups of freshly brewed tea, especially green tea, can help provide protection against many chronic diseases.
Not a tea drinker? If your taste buds aren't used to the astringent notes of regular tea, try incorporating it into smoothies, soups, oatmeal, or juices you prepare to hide the taste. In fact, by doing so, the catechins in green tea may actually work in concert with other foods to enhance their health benefits.
References
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Bhagwat S, Haytowitz DB; US Department of Agriculture, Agricultural Research Service. USDA database for the flavonoid content of selected foods: release 3.2. http://www.ars.usda.gov/SP2UserFiles/Place/80400525/Data/Flav/Flav3.2.pdf. Updated November 2015.
J Nutr. 2003 Oct;133(10):3303S-3309S.
Westerterp-Plantenga MS. Green tea catechins, caffeine and body-weight regulation. Physiol Behav. 2010;100(1):42-46.
Pang J, Zhang Z, Zheng TZ, et al. Green tea consumption and risk of cardiovascular and ischemic related diseases: a meta-analysis. Int J Cardiol. 2016;202:967-974.
Front Microbiol. 2014; 5: 434.