Tea is generally consumed in the form of black, oolong or green tea; which are all preparations originating from Camellia sinensis, a small plant grown mainly in China and southeast Asia.
By Zarwa Batool, Sonia Jamil, Abdul Majid, Gulnaz Kanwal, Masood Ahmad
Tea is cultivated in approximately 30 countries worldwide and is consumed globally. Although the level of tea consumption varies around the world, it is believed to be second only to water.1 Black tea is consumed predominantly in Western and some Asian countries and green tea is consumed predominantly in China, Japan, India, and a number of countries in north Africa and the Middle East. Tea is an ancient drink that stirs the imagination and soothes the soul. From its earliest beginnings in China to its current status as the most popular beverage in the world after water, tea has a history that is inspiring and disheartening, uplifting and disturbing
Growing and Processing of Tea
All true tea, green, black and white, is derived from C. sinensis, an evergreen shrub of the Theaceae family. Unlike black tea, which is fermented, green tea is produced in a non-fermented process. Green tea may be consumed in the form of a brewed beverage or capsular extract. In some countries, tea is used as dietary supplements. Successful tea cultivation requires moist humid climates provided most ideally by the slopes of Northern India, Sri Lanka, Tibet and Southern China. Green tea is consumed predominantly in China, Japan, India and a number of countries in North Africa and the Middle East, whereas black tea is consumed predominantly in Western and some Asian countries
Tea and Health Benefits in modern Times
Numerous scientific publications now attest to the health benefits of both black and green teas including clinical and epidemiological studies. Although all tea contains beneficial antioxidants, high-quality green and white teas have them in greater concentrations than black tea. Today, scientists believe that the main active ingredients of green tea include the catechins and the theanine. Their benefits are summarized below.
Tea and cancer
Studies on the health benefits of drinking tea, particularly green tea, are finding exciting results, particularly in cancer research. Modern studies in both Asia and the West have provided encouraging results indicating that drinking green tea contributes to fighting many different kinds of cancers including stomach, esophageal, ovarian and colon. These studies show that the onset of cancer patients in Japan who had consumed 10 cups of green tea per day was 8.7 years later among females and 3 years later among males, compared with patients who had consumed less than three cups per day. As such, a possible relationship between high consumption of green tea and low incidence of prostate and breast cancer in Asian countries, where green tea consumption is high, has been postulated. However, because of the many variables in lifestyle inherent to such a study, a definitive link between green tea and its cancer effects cannot as yet be concluded
Tea and weight loss
Studies have shown that green tea (C. sinensis) catechins may have favorable effects on body composition in humans. The authors report on the influence of a green tea catechins beverage on body composition and fat distribution in overweight and obese adults during exercise-induced weight loss
Tea and type 2 Diabetes
Green tea helps to control blood sugar level, body fat burning properties and weight-loss benefits in those subjects experiencing properties known as the metabolic syndrome, a precursor to type 2 diabetes, and builds on a greater body of knowledge related to two significant health issues today: weight gain and lack of blood sugar control. Epidemiological research suggests that Japanese adults who consume six or more cups/day of green tea have a 33% lower risk of developing type 2 diabetes compared to those who consume one cup/day or less. Risk reduction appears to be more pronounced in women compared to men.
Green tea for skin treatment
Treatment of green tea polyphenols to skin has been shown to modulate the biochemical pathways involved in inflammatory responses, cell proliferation and responses of chemical tumor promoters as well as ultraviolet light-induced inflammatory markers of skin inflammation. Topical treatment with EGCG on mouse skin results in prevention of UV induced immunosuppression and oxidative stress. The protective effects of green tea treatment on human skin either topically or consumed orally against UV light-induced inflammatory or carcinogenic responses are not well understood.
Some studies have also shown the positive impacts of green tea on the following types of cancer:
- Colorectal (bowel)
- Esophageal (throat)
Green tea side Effects and risks
There are little to no known side effects or contraindications to drinking green tea for adults. However, the following risks or complications should be made clear:
- Caffeine sensitivity – those with severe caffeine sensitivities could experience insomnia, anxiety, irritability, nausea, or upset stomach.
- Blood thinners – those taking blood thinners (anticoagulant drugs) such as Coumadin/warfarin should drink green tea with caution due to its vitamin K content. It’s also recommended to avoid green tea and aspirin, because they both reduce the clotting effectiveness of platelets.
- Other stimulants – if taken with stimulant drugs, green tea could increase blood pressure and heart rate.
Authors : Zarwa Batool, Sonia Jamil, Abdul Majid, Gulnaz Kanwal, Masood Ahmad Univeristy of Agriculture Faisalabad