Green tea has a place in traditional medicine, as an ingredient in modern food products and as a dietary supplement. It contains caffeine and antioxidant compounds that are effective in increasing your metabolism through a complex physiological process. Although green tea is a relatively safe product, overuse can cause serious health problems and interactions with certain medications. Consult your health care provider before taking green tea in supplement form or drinking multiple cups of tea per day.
Green Tea
Green tea is made from the leaves of the Camellia sinensis plant. It has a long history of use in traditional Chinese and Indian medicine and has more recently evolved into a variety of modern products, such as sports drinks, chewing gum and dietary supplements. Although black and oolong teas are made from the same plant, green tea retains more health benefits because it is not fermented.
Metabolism
Green tea and green tea extracts boost your metabolism by stimulating your sympathetic nervous system and improving insulin sensitivity. Its activity is due to the presence of caffeine and antioxidant compounds called catechins. Both caffeine and catechins inhibit enzymes involved in fat storage and energy regulation. Through a chain of cellular reactions, they maintain high levels of noradrenaline, which causes your body to oxidize fat at a higher rate.
Research
A variety of clinical studies provide evidence that green tea can speed up your metabolism. A study in the 2008 issue of "The American Journal of Clinical Nutrition" found that people burned a higher percentage of body fat to fuel their exercise after taking green tea extracts. Green tea's effectiveness was further supported by a study published in the 2009 issue of "The Journal of Nutrition" that linked green tea catechins with reduced abdominal fat. Obese patients with metabolic syndrome also benefited from the daily consumption of green tea or supplements over an eight-week study. Results published in the 2010 "Journal of the American College of Nutrition" showed that green tea helped them lose weight and lower their bad cholesterol levels.
Hazards
Although green tea is considered a relatively safe product, it should be used with caution. Drinking excessive amounts of green tea increases your caffeine intake to a level that may cause health problems, such as headaches, an irregular heartbeat and tremors. It can also interfere with your absorption of iron and interact with certain medications, such as those used in cancer treatment and amphetamines.
References
- Medline Plus: Green Tea
- University of Maryland Medical Center: Green Tea
- "Physiology and Behavior"; Effectiveness of Green Tea on Weight Reduction in Obese Thais: A Randomized, Controlled Trial; Paradee Auvichayapat et al.; February 2008
- "The American Journal of Clinical Nutrition"; Green Tea Extract Ingestion, Fat Oxidation, and Glucose Tolerance in Healthy Humans; March 2008
- "The Journal of Nutrition"; Green Tea Catechin Consumption Enhances Exercise-Induced Abdominal Fat Loss in Overweight and Obese Adults; Kevin Maki et al.; February 2009
- "Journal of The American College of Nutrition"; Green Tea Supplementation Affects Body Weight, Lipids, and Lipid Peroxidation in Obese Subjects with Metabolic Syndrome; Arpita Basu et al.; February 2010
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