A naturally occurring chemical found in beans, tea, energy drinks, cocoa, and chocolate including leaves of tea plants is consumed all over the world to boost alertness and fight fatigue. Further who consume excess caffeine may experience restlessness, insomnia, or irregular heartbeat problems.
The average amount of caffeine in a 230 ml serving of green tea is around 35 mg. This amount depends largely on the variety of tea plant as tea made3 with older leaves usually has less caffeine than tea made with younger tea leaves
The amount of caffeine in some common foods and beverages are here under,
Caffeine is a widely used stimulant if consumed in the recommended amount, it is considered very safe.
For Adults, the safe limit is considered to be around 6 mg/kg of body weight. Overall, green tea is low in caffeine compared to other caffeinated beverages, so 200 mg of caffeine is found in around four 230 ml cups of green tea and is considered very safe.
Caffeine may aid loss weight or prevent weight gain as it suppresses the appetite reducing the desire for tea. Due to a moderate amount of caffeine body generates more heat and energy from digesting food.
Caffeine may improve stamina during physical performance. A study showed that caffeine can increase stamina during sports performance with a reduction in perceived exertion.
Green tea or Coffee contains antioxidants namely polyphenols which act on various pathways and effects adenosine receptors in the brain. However, further research is needed.
Caffeine may help protect people from blepharospasm, a condition in which you cannot control blinking or other eyelid movements like twitching, which is caused by abnormal brain functions. Further, studies have shown that caffeine may help protect the lens of the eye against damage which could ultimately lead to the formation of cataracts.
No doubt that caffeine is beneficial but some studies highlight the potentially harmful effects of caffeine.
Research in middle school students found that higher intake of caffeine may be linked to higher weight, lower academic achievement, and worsening symptoms of anxiety and depression.
Consuming caffeine before bedtime even 3 to 6 hours may significantly disrupt sleep as caffeine can reduce objectively measured total sleep time by more than one hour.