"[T]he evidence generally supports that consumption of up to 400 mg caffeine/day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status," the study states.
For reference, a tall (12 oz.) Pike Place roast coffee from Starbucks contains 235 milligrams of caffeine and a grande (16 oz.) iced coffee contains 190 milligrams. In homemade varieties, a 12 oz. cup of Folgers is between 60 and 80 milligrams and a single Green Mountain Keurig K-Cup contains 75 milligrams. A Diet Coke lands around 46 milligrams.
Should you start putting down five cups a day if you usually have two? Probably not. However, if you're drinking that much, and you're otherwise healthy, there probably isn't an urgent need to cut back. Some people are able to handle caffeine better than others due to their tolerance or size, among other factors. Due to the nature of the reviewed papers, the study isn't able to provide details on the health consequences of consuming in excess of 400 milligrams per day.