New research suggests that green tea can become unhealthy if its ingredients, the polyphenols, are used in high doses, for example as an extract. Green tea is generally considered healthy and is said to be beneficial due to its high levelsAntioxidant contenta longer life. Researchers at ETH Zurich are now questioning previous assumptions about how these active ingredients work.
When can green tea become unhealthy?
The catechins contained in green tea belong to the group of polyphenols and are considered antioxidants. This means that they counteract or prevent oxidative stress in the body caused by aggressive free oxygen radicals. Until now, scientists assumed that the catechins neutralize these free radicals and thus prevent damage to cells or DNA. One source of free oxygen radicals is metabolism, for example when the mitochondria work to produce energy. Now the study authors and colleagues from the University of Jena have taken a closer look at how these substances work in the nematode C. elegans. They came to a different, seemingly paradoxical conclusion: instead of suppressing oxidative stress, the catechins in green tea promote this process. Polyphenols from green tea initially increase oxidative stress in the short term. However, this subsequently increases the defense capacity of the cells and the organism. In addition, cachetins are not actually antioxidants, but pro-oxidants and improve immunity, similar to a vaccination.
However, this increase in defense capacity does not manifest itself through the immune system, but rather through the activation of genes that produce certain enzymes. It is these enzymes that inactivated free radicals in the nematode during research. The study authors therefore recommend against taking green tea extracts or concentrates as they can be toxic. High doses of catechins inhibit the mitochondria to such an extent that cell death occurs, which can be particularly dangerous in the liver. Anyone who consumes an overdose of these polyphenols risks damaging their organs. While most catechins are found in Japanese green tea, other types of tea also contain sufficient amounts of these polyphenols. Black tea, on the other hand, contains a significantly lower proportion because these are largely destroyed by the fermentation process. That's why green tea is preferable to black tea, as the authors saythis studyclaim.
