Main research findings

Green tea is widely consumed for its health benefits, but research indicates that it may have some side effects.

For example, EGCG, a type of catechin found in green tea, has been shown to inhibit the growth of multiple myeloma cells according to . However, the same study concludes that EGCG alone has limited anticancer effects. Moreover, states that the combined use of tacrolimus and green tea may lower tacrolimus blood levels and increase the risk of transplant rejection. Furthermore, shows that green tea extract may help prevent metabolic syndrome by suppressing insulin resistance in mice. However, these studies do not clarify the relationship between green tea consumption and side effects.

Reasons for side effects

The side effects of green tea are caused by various components contained in it. For instance, caffeine can lead to side effects such as insomnia, anxiety, and increased heart rate. Catechins may cause gastrointestinal irritation and allergic reactions. In addition, green tea contains components that inhibit iron absorption, potentially worsening anemia.

Common side effects

Insomnia

Green tea contains caffeine, which has a stimulating effect and can cause insomnia. shows that mice receiving green tea extract exhibited lower blood pressure and improved endothelial function. This suggests that green tea may have positive effects on cardiovascular health. However, caffeine can cause insomnia, so avoid drinking green tea before bed.

Gastrointestinal irritation

The catechins in green tea can irritate the gastrointestinal tract, potentially causing side effects such as indigestion and nausea. demonstrates that encapsulating catechins in nanocapsules may reduce gastrointestinal irritation and enhance the therapeutic effects of treating gastric ulcers. It is advisable to avoid green tea when on an empty stomach or if you have a weak gastrointestinal system.

Allergic reactions

Green tea contains components that can trigger allergic reactions. indicates that EGCG3''Me, a type of catechin found in green tea, when combined with hesperetin, enhances the suppression of allergic reactions. Those with green tea allergies should refrain from consuming it.

Anemia

Green tea contains components that inhibit iron absorption, potentially worsening anemia. To promote iron absorption, it is recommended to consume green tea with foods rich in vitamin C.

Other side effects

Side effects such as headache, dizziness, palpitations, and sweating have been reported after green tea consumption. These side effects are more likely to occur with high caffeine intake.

Countermeasures for side effects

Adjust caffeine intake

It is important to adjust caffeine intake to avoid the side effects of green tea. Caffeine is present not only in green tea but also in coffee, black tea, chocolate, and other foods. Excessive consumption of these foods can lead to side effects such as insomnia, anxiety, and increased heart rate.

Adjust the time of intake

The time of day you consume green tea also matters. Drinking green tea before bed can lead to sleeplessness due to the effects of caffeine. If you drink green tea before bed, do so at a time that allows caffeine to dissipate.

Change how you drink

The way you drink green tea can also help reduce side effects. Drinking green tea cold slows the absorption of caffeine and reduces the likelihood of side effects. Diluting green tea also helps reduce caffeine intake.

Adjust intake based on your physical condition

It is also important to adjust your intake of green tea according to your physical condition. Pregnant women, breastfeeding mothers, and individuals with weakened gastrointestinal systems should avoid consuming green tea.

Comparison between studies

Commonalities in studies

Many studies have shown that green tea has health benefits such as antioxidant and antibacterial properties. Studies have also suggested that consuming green tea may have positive effects on cardiovascular health and cancer prevention.

Differences in studies

The results of studies regarding the side effects of green tea have varied. For example, research findings on whether green tea consumption causes insomnia are not consistent. This is likely due to differences in study subjects, green tea types, and intake levels.

Precautions for applying research findings to real life

While green tea has health benefits, it also has the potential for side effects. When consuming green tea, pay attention to your caffeine intake and physical condition, adjusting your intake as needed.

Current limitations of research

Research on the side effects of green tea is still not comprehensive. Further studies are needed to clarify the relationship between green tea consumption and side effects.

Future research directions

Research on the side effects of green tea should investigate how factors such as green tea type, intake level, intake time, and physical condition affect side effects. Research into methods for mitigating the side effects of green tea is also necessary.

Conclusion

Green tea has health benefits but also has the potential for side effects. When consuming green tea, pay attention to your caffeine intake and physical condition, adjusting your intake as needed. Research on the side effects of green tea is still insufficient, and further research is needed.