Tea : The ancient beverage
Tea is the most consumed beverage in the world that has several health effects from bone health to weight loss. According to American Journal of Clinical Nutrition (AJCN) the antioxidants from the tea have helpful benefits in human health such as prevention of chronic illness, treatment of mood disorder, weight loss etc. Following are the health effects of tea:
- Improved bone health: Recent research has found a positive connection between drinking green tea and osteoporosis which is a major health problem nowadays for elderly people especially women (because of their low estrogen level after menopause). Green tea and its bioactive compounds polyphenols/catechins (collectively known as green tea polyphenols or GTP), such as EGCG (Epigallocatechin gallate), ECG(Epicatechin gallate), EC (Epicatechin) and EGC (Epigallocatechin), may decrease the risk of bone fracture by improving the bone mineral density (BMD) and support osteoblastic (osteoblasts are bone forming cells) activities. Green tea has more bone health benefits/osteoprotective effects than other teas such as black tea or oolong tea due to decreased oxidative stress, high concentration of antioxidant enzymes and decreased expression of proinflammatory mediators [1]. Other than catechins tea also has flavonoids (such as phytoestrogen, isoflavone and lignans), caffeine and dietary fluoride that also can increase osteoporotic progression and improve BMD.
- Weight loss: Due to its high concentration of caffeine and polyphenols and antioxidants tea consumption is an effective way for weight loss. The most effective weight loss tea includes oolong tea, white tea, mint tea, red rooibos tea and matcha green tea which helps in weight reduction by increasing fat metabolism and by boosting lipolysis (fat breakdown) and blocking adipogenesis (fat cell formation). The African red rooibos tea contains an unique and powerful flavonoid aspalathin that can reduce the stress hormones which trigger hunger and fat storage [2]. The catechin contents (EGCG) of Japanese green matcha tea is 30 times higher than regular green tea which makes it a very effective weight loss tea. Though its caffeine concentration is also way high, so it may not be applicable to everyone.
- Boosting immunity: Several studies show that tea can positively influence the immune cells, so can boost immunity. Tea EGCG can modulate the production of cytokines (such as IL1, IL6, IL12 and TNF1- alpha) produced by the immune cells such as T cells, B cells, dendritic cells and antigen presenting cells which play key roles in immunity against microbial pathogens and tumors. See my related post for more background on immunity.
- For heart attack, stroke and cancer prevention: Tea drinking (even 2 cups/day) supports healthy blood pressure and arterial function and can help to reduce stroke, heart attack, some types of cancer and other cardiovascular disease. The green tea polyphenols and the theaflavin and thearubigins from black tea have antioxidant/free radicals extraction activity that can protect cells from DNA damage caused by reactive oxygen/free radicals. Research shows that green tea catechins can activate detoxification enzymes glutathione S transferase and quinone reductase that may help to protect against tumor development [3].
- Digestion and sleeping aid: Tea has a positive impact on digestion (such as green tea, mint tea, chai tea, herbal tea and ginger tea) and sleeping (such as chamomile tea and lavender tea).
Though tea is a healthy alternative of caffeine and calorie containing beverages some tea constituents may have negative impact on health and not advisable for everybody. I will write about this in my next post.
References:
3. http://www.cancer.gov/about-cancer/causes-prevention/risk/diet/tea-fact-sheet
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