Caffeine in Green Tea and Coffee

In these modern days, caffeine lovers are prevalent all over the world. The most popular caffeinated beverages include coffee and tea. While there have been numerous studies looking at the health benefits of these beverages, there has also been interesting findings about the characteristics of caffeine in green tea. It turns out that the same caffeine present in coffee has a very different effect on our bodies when consumed in the form of green tea. How and why is this possible? When we observe the behavior of caffeine that is consumed in the form of green tea, we can understand how the components of food synergistically interact with one another and affect our blood and bodies.

In today’s world, caffeine is the most frequently ingested psychoactive substance with approximately 80% consumed in the form of coffee. It is also naturally found in tea and chocolate [1, 2]. The main effect and purpose of caffeine consumption is to achieve mental alertness. Caffeine intake is also associated with increased urination and headache reduction as it relaxes smooth muscle, stimulates cardiac muscle, and promotes diuresis [3].

When coffee is consumed in controlled amounts, it is considered safe- the dosage limit may vary from person to person. However, when overdosed, the side effects include restlessness, irritation, anxiety, and a rapid heartbeat. Studies show that higher dosages may also lead to serious health and mental problems such as hypertension, depression, muscle tissue breakdown, and increased risk of bone fracture [4,5,6]. The negative effects of coffee overdose are usually linked to the high dosage of caffeine intake. However, when the same amount of caffeine is consumed in the form of green tea, it has a much more muted reaction in the body.

In green tea, a single leaf actually contains more caffeine than a coffee bean. However, when the tealeaves are brewed into a cup of hot tea, the caffeine concentration becomes lower than the concentration in a cup of coffee. Furthermore, while coffee’s primary component is caffeine, green tea contains other compounds such as theanine that complements caffeine. Theanine, known for its positive psychological effects, is converted to catechins as the tea tree is exposed to sunlight over a long period of time [7]. This yields to a stronger and richer taste. Theanine and catechins together contribute to green tea’s unique characteristics that allow it to stand out from other caffeinated products.

The average half-life of caffeine for adults is about two to seven hours (half-life is the amount of time it takes for a quantity of a substance to be reduced to half the original amount) [13,14]. However, when caffeine is combined with catechins and theanine, the body will eliminate caffeine much faster [13, 14, 15, 16]. Moreover, when theanine binds with caffeine, the bound molecules become insoluble and results in less absorption and weaker activities inside the body [8,9].

The combination of theanine and caffeine, as compared to caffeine alone, can further induce greater effects of increased alertness while reducing headache and weariness [10]. In short, a large portion of caffeine in green tea is biochemically bound and suppressed by other compounds, making it less impactful in our body as it does with coffee.

In addition to their counter-balancing effects, theanine and caffeine in combination has shown to improve attention task performance. This may support the advice to consume green tea when performing precarious tasks such as overnight driving. Green tea may not only help with staying awake, but it may also help with keeping alert to avoid making severe mistakes. Furthermore, the interactions between catechins and caffeine stimulate the thermogenic effect (generation of heat in human body) and could potentially help manage obesity in the long run [12]. Aside from the complementary effects between caffeine and the neighboring compounds, green tea is already known for numerous benefits, such as its powerful antioxidant properties.

In conclusion, the combination of these two major compounds, theanine and catechins, in green tea leaves (that have received a plentiful amount of sunlight) provide synergistic effects with caffeine. When we acknowledge the interactive relationship between green tea and caffeine, we can understand that green tea may offer greater benefits than coffee, as coffee can have harsh effects on our body. The compounds in green tea together also play an important role in offering a richer and deeper flavor of nature in a cup of tea, which we can freely enjoy every day.


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