100mg of Caffeine? I tried a couple of cans of Jolt Cola back in the day, and with it's (then) 71mg of Caffeine I thought my brain was going to pop out of my skull. No idea how the drinkers of Club-Mate don't have health problems from this.
Red Bull, Rockstar, Monster and similar energy drinks have ~32mg/100ml (I've seen anything from 28 to 32, but 32 seems to be a legal limit and the most popular).
A 500ml can of Rockstar or Monster has 160mg of caffeine.
The caffeine content of regular caffeine pills I can buy at the pharmacy (plain packaging, just branded as "caffeine") is 0.2g per pill, i.e. 200mg (or 100mg per half).
A cup of regular coffee typically contains about 95mg of caffeine.
If a handful of servings of 100mg of caffeine per day would pose a major health risk, the majority of the population in developed nations would already be affected, whether they drink Club Mate or not.
For reference: I would say that in a given day I don't think I've ever drunk more than two liters of Club Mate. Normally I drink about two bottles over the period of a work day. I barely ever drink it outside of work.
I would say that on a typical day (including holidays and weekends) I consume between 100mg and 250mg of caffeine. That's the equivalent of one to two-and-a-half cups of coffee.
EDIT: Google seems to agree that up to 400mg of caffeine a day is safe for most healthy adults. I should probably also point out that some people are just naturally very sensitive to caffeine, so that may explain why you reacted so strongly to Jolt Cola -- especially if you do not normally consume any other sources of caffeine like coffee, tea or dark chocolate.
I don't want to be too down on peoples' beverage or anything. I enjoy a decent cup of coffee myself now and then. But... yeah, I'm also a little distressed at the culture of heavy drug use to get through the working day.
"In crunch time I've had like 10 bottles in a day", says the Wikimedia engineer. Ugh. What other unhealthy habits should we start to be more productive at our jobs? Most of us probably have plenty of free sugary snacks in the office already, so perhaps we can start smoking or become alcoholics to relieve stress on the job?
