I can kind of back this research up, i have actually been drinking this in and off for over 11 years , more on than off ( at the moment ) 2- 3 cups of strong good quality green tea a day , while having it i haven't had symptoms of flu in 11 years, and not had symptoms of covid that i  have noticed in the last 18 months, also never had common cold which i always caught of my son before drinking this regularly and he always seemed to have cold. he started drinking this in March 2020 too  and not had a thing till he stopped drinking this for a few days recently,  he started with cold but once he started again the cold had gone in 2 days , where normally it used to go on for ages. he only has 1 a day though with being young his immune system is more healthier. I know it can deplete magnesium and Iron so we always make sure this is kept topped up too.