I have been taking L-Theanine 100 mg once or twice a day as well one mug of green tea and another black tea for over a year.
I take many other supplements as well but I don't know if they are making any difference apart from drilling a hole in my wallet
My selection of supplements is based on successful use of these supplements on rats. I am fully aware that humans are not rats and clinical trials are necessary to establish efficiency and correct dose.
At the end of the day I hope against hope that money is not thrown down the drain and these supplements may be supporting my general health and boosting my hopes as a good placebo should.
I may add that many times, I have thought of quitting supplements because they may pose a hazard, but simply couldn't. I could not afford loosing the placebo element.