(Nigeria Natural Medicine Development Agency)
Tea is the most consumed beverage in the world, after water. 78 per cent of the tea consumed worldwide is black and only about 20 percent is green. Green tea is a type of tea that is made from Camellia sinensis leaves that have not undergone the same withering and oxidation process used to make oolong and black tea. Green tea originated in China, but its production has spread to many countries in Asia and the rest of the world.
Several varieties of green tea exist, which differ substantially because of the variety of C. sinensis used, growing conditions, horticultural methods, production processing, and time of harvest.
Composition and benefits
Phytochemical analysis shows the active ingredients in green tea to be chemicals known as polyphenols, flavonoids or cathecins. Green tea also contains caffeine, theobromine, theophylline, B vitamins and Vitamin C. Potential medicinal actions of green tea include lowering cholesterol level, antimicrobial, antioxidant, anti-inflammatory, anticancer and anti-radiation biochemical activities.
Some Japanese studies reported that drinking five to ten cups or more of green tea daily appeared to reduce the risk of stomach cancer and could possibly delay cancer onset or recurrence. Other health benefits attributed to green tea through some research include lowered risk of death from cardiovascular causes, increased weight loss, reduced risk of Alzheimer’s and Parkinson’s disease and lowered risk of type II diabetes.
However, although numerous claims have been made for the health benefits of green tea, human clinical research is necessary to provide conclusive evidence of any effects.
Presentation Green tea may be available as bottled and sweetened with sugar or an artificial sweetener, in single tea bags, as loose-leaf or in instant-powder, green tea supplements which are sold in capsule form or liquid extract.
It appears that moderate consumption of green tea is safe but excessive consumption may produce effects associated with excessive caffeine consumption, such as insomnia, nervousness and rapid heartbeat.
Megan Wares of MedicalNewsToday warns against use by people with severe caffeine sensitivities because in addition to the above reactions, they could also experience anxiety, irritability, nausea, or upset stomach with green tea.
Those taking blood thinners (anticoagulant drugs) such as Coumarin/warfarin should drink green tea with caution due to its vitamin K content. Concomitant use of green tea and aspirin should be avoided because they both reduce the clotting effectiveness of platelets. If taken with stimulant drugs, green tea could increase blood pressure and heart rate.
Green tea interferes with the chemotherapy drug bortezomib (Velcade) and other boronic acid-based proteasome inhibitors, and should be avoided by people taking these medications. Just as green tea supplements contain high levels of active substances that can trigger side effects and interact with other herbs, supplements, or medications, they may also contain other substances unsafe for health or with unproven health benefits.
A study by Eromosele et al in Ogun State, Nigeria, revealed that acceptable green tea can be obtained from Nigerian tea leaves in terms of chemical constituents, especially for the high epigallocatechin gallate (EGCG) content.
Considering the increasing daily consumption of green tea worldwide, there should be more research to explore the benefits, safety and potentials of green tea in Nigeria. Obalolu and Fasins report that tea (Camellia sinensis L.) production in Nigeria started in 1982 on commercial basis, the initial planting materials having been brought in from Cameroun and Kenya at various times. Though the major problems of the farmers was the procurement of input materials like fertilizers, irrigation equipment and tractors as well as land for cultivation, the pricing of Nigeria tea is favourable.
There is, therefore, a bright future for the tea industry in Nigeria if new areas for expansion can be found. There are opportunities in the cultivation, production, distribution, sales, use of and research on green tea in Nigeria.