Green Tea

Green Tea

Green tea, native to China and India, is a delicious variety of tea that is made from unfermented leaves of Camellia sinensis plant. The tea contains high concentration of powerful antioxidants called polyphenols, which are known to fight free radical damage and prevent a broad range of diseases. Green tea has been consumed and hailed for its therapeutic benefits for thousands of years globally. Enjoyed hot or cold, or even in the form of powder, capsule and pills, green tea is considered as a superfood and has been implicated in benefiting almost every organ system in the body.

Benefits of Green Tea

An overwhelming body of clinical research supports the following health benefits of green tea:

Improves Body Composition

A 2009 study published in the Journal of Nutrition found that green tea consumption can help decrease body fat in overweight and obese persons.[1] The study involved overweight and obese participants who were randomly assigned to receive a beverage containing approximately 625 mg of green tea or placebo, and they were asked to maintain constant energy intake and engage in moderate intensity exercise for 12 weeks. After the treatment period, researchers observed that participants who consumed green tea had a significant reduction in total abdominal fat area compared to those who took placebo.

Reduces Risk of Cardiovascular Events and Stroke

Heart disease and stroke are among the top causes of death worldwide. In a meta-analysis of 9 studies from different research groups, researchers found that a daily dose of 500 ml of green tea (2-3 cups) can help improve blood flow within the blood vessels of the heart and brain, thereby lowering the risk of heart disease and stroke.[2]

Improves Cholesterol Levels

Green tea consumption is associated with a significant improvement in cholesterol profile. In one study, 33 subjects with abnormal cholesterol levels were given 250 mg of green tea via capsule for 8 weeks.[3] After the treatment, the researchers observed a 3.9% reduction in total cholesterol and a 4.5% reduction in low density lipoprotein cholesterol (LDL).

Improves Cognition

A 2011 study published in the Journal of Medicinal Food found that green tea extract supplementation in people with mild cognitive impairment resulted in a significant improvement in cognitive function. After 16 weeks of treatment, the researchers observed that subjects who took green tea extract had increased brain theta waves in their electroencephalogram results, which is indicative of cognitive alertness.[4]

Maintains Healthy Skin

Studies show that catechins in green tea possess strong anti-aging properties. In one study, researchers found that 1402 mg catechins, consumed via beverage, was shown to cause ultraviolet protection and enhanced blood flow to the skin of older women after 6-12 weeks of treatment.[5]

Improves Blood Sugar Levels

There is increasing evidence that green tea consumption can help stabilize blood sugar levels. For instance, one study found that both 110 mg and 220 mg of green tea appeared effective at suppressing the amount of glucose that enters the bloodstream of normal and pre-diabetic individuals over the next 1-2 hours, resulting in lower blood sugar levels.[6]

Reduces Cancer Risk

Green tea is highly rich in powerful antioxidants which are known to combat various types of cancer. A meta-analysis of observational studies found that women who regularly drink green tea had a 22% lower risk of developing breast cancer.[7] In another study involving 69,710 Chinese women, researchers found that habitual green tea drinkers had a 57% lower risk of colorectal cancer.[8]

Wards Off Depression

According to experts, the more green tea you drink, the less depressed you will feel. In fact, a Japanese study involving 1,058 elderly individuals proved that green tea really have an anti-depressant effect.[9] According to the study,  participants who drank four or more cups of green tea per day experienced a significant reduction in depressive symptoms compared to those who did not.

Improves Dental Health

Catechins from green tea are not only potent antioxidants; they also possess strong antibacterial properties. Several high quality studies show that consumption of green tea catechins can help improve dental health by inhibiting the growth of several harmful bacteria in the mouth including Streptococcus mutans.[10-12]

Increases Life Expectancy

Green tea drinkers tend to live longer according to research. In a study of 40,530 Japanese adults, researchers found that subjects who consumed 5 or more cups per day   were significantly less likely to die during an 11 year period.[13] The researchers observed that death of all causes is 23% lower in women who regularly drink green tea.

References:

1. Maki KC, Reeves MS, Farmer M. Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults. The Journal of nutrition. 2009; 139(2):264-70.
2. Ras RT, Zock PL, Draijer R. Tea consumption enhances endothelial-dependent vasodilation; a meta-analysis. PloS one. 2011; 6(3):e16974.
3. Batista Gde A, Cunha CL, Scartezini M, von der Heyde R, Bitencourt MG, Melo SF. Prospective double-blind crossover study of Camellia sinensis (green tea) in dyslipidemias. Arquivos brasileiros de cardiologia. 2009; 93(2):128-34.
4. Park SK, Jung IC, Lee WK. A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study. Journal of medicinal food. 2011; 14(4):334-43.
5. Heinrich U, Moore CE, De Spirt S, Tronnier H, Stahl W. Green tea polyphenols provide photoprotection, increase microcirculation, and modulate skin properties of women. The Journal of nutrition. 2011; 141(6):1202-8.
6. Butacnum A, Chongsuwat R, Bumrungpert A. Black tea consumption improves postprandial glycemic control in normal and pre-diabetic subjects: a randomized, double-blind, placebo-controlled crossover study. Asia Pacific journal of clinical nutrition. 2017; 26(1):59-64.
7. Sun CL, Yuan JM, Koh WP, Yu MC. Green tea, black tea and breast cancer risk: a meta-analysis of epidemiological studies. Carcinogenesis. 2006; 27(7):1310-5.
8. Yang G, Shu XO, Li H. Prospective cohort study of green tea consumption and colorectal cancer risk in women. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2007; 16(6):1219-23.
9. Niu K, Hozawa A, Kuriyama S. Green tea consumption is associated with depressive symptoms in the elderly. The American journal of clinical nutrition. 2009; 90(6):1615-22.
10. Naderi NJ, Niakan M, Kharazi Fard MJ, Zardi S. Antibacterial Activity of Iranian Green and Black Tea on Streptococcus Mutans: An In Vitro Study. Journal of Dentistry (Tehran, Iran). 2011;8(2):55-59.
11. Narotzki B, Reznick AZ, Aizenbud D, Levy Y. Green tea: a promising natural product in oral health. Archives of oral biology. 2012; 57(5):429-35.
12. Yu H, Oho T, Tagomori S, Morioka T. Anticariogenic effects of green tea. Fukuoka igaku zasshi = Hukuoka acta medica. 1992; 83(4):174-80.
13. Kuriyama S, Shimazu T, Ohmori K. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. JAMA. 2006; 296(10):1255-65.