The Mayo Clinic determined that healthy adults can safely ingest about 400 milligrams of caffeine per day. Going above that affects how well you sleep and may lead to other unpleasant symptoms. But what does that number mean for the consumer? Redditor SportsAnalyticsGuy created this chart, listing how many of the more familiar caffeine sources it takes to reach 400 milligrams (you can enlarge the image here). The data is from the National Center for Biotechnology Information. If you find the top graph confusing, he also plotted the list a different way. This is the percentage of the safe dosage of caffeine reached by one serving of each product.
It turns out that I have exceeded the safe level of both coffee and tea daily for about forty years. I am also surprised that Vivarin and Dristan still exist. -via Digg