Earlier quoted context omitted.
I think moderate consumption is a function of tolerance and the specific metabolism of the person combined. I remember reading a comment in HN, where the commenter had a genetic trait which slowed caffeine metabolism by 4 times. So, he had it inside his system 4 times longer, and caffeine had no positive effect on him. However, let's not digress. I'm not a body hacker, and I don't like to mess with my body much, howe…
> Black tea is a good aid for sustaining my focus. It improves focus, but doesn't create the same stress on my body. Black tea contains 30–90 mg of caffeine per cup (and some theobromine and theophylline, which are similar to caffeine, and also stimulants.) Giving up coffee because of the caffeine but dinking black tea instead is self-defeating.
I don't reduce coffee because of caffeine, but because it affects my appetite, makes me tense when I drink too much, and causes heart palpitations and makes me uncomfortable. Black tea doesn't do any of that.