This page is for interesting nutritional facts I've found.
The recommended maximum caffeine per day for adults is 400 mg.
Excessive caffeine intake is 500 mg to 1500 mg, and can cause gastrointestinal upset, and also known to increase heart rate and irregularity, blood pressure, diuresis, psychomotor agitation, anxiety, and insomnia.
Fatal caffeine intake is 10-12 g.