There are a lot of advantages to drinking coffee, ranging from the appealing flavor to the supposed health benefits, but it's got to be the caffeine content that's mostly responsible for its massive popularity. Millions of people depend on the caffeine content in coffee to wake them up, increase their alertness, and prepare them for the challenges of the day. The right amount of caffeine can also improve mental efficiency, athletic performance, and exercising endurance. The question that many people are asking is "How much caffeine is too much"?
Since everyone's physiology, body weight, and tolerance to caffeine is different, there's no magic number that would apply to all coffee drinkers. To complicate matters, a lot of factors affect caffeine content, including the method of roasting, grinding, and brewing the coffee. One of the most authoritative source on caffeine content is Mayo Clinic Web site, which not only lists the amount of milligrams of caffeine in different sizes and types of coffee, but it also suggests a maximum amount of caffeine that coffee drinkers should keep in mind--especially those who experience side effects or caffeine sensitivity. While 500 mgs every day would be too much caffeine for some people and inconsequential for others, it's a helpful reference point for people who want to monitor their caffeine intake.
Considering that an 8 ounce cup of generic brewed coffee can contain between 95 and 200 mgs of caffeine, it might not take that long to reach the 500 mg threshold--especially since many people opt for the medium and large sizes. If you're interested in getting specific information on how much caffeine is in coffee at Starbucks and McDonalds, the Mayo Clinic site can shed some light on those questions. I don't know why Dunkin Donuts isn't included in its chart on caffeine content. They do, however, provide information on the amount of caffeine in espresso, instant coffee, and decaffeinated coffee.
Decaffeinated coffee? "How can their be caffeine in coffee that is decaffeinated?" you might ask. To borrow a weasel word from the advertising industry, most types of decaffeinated coffee is "virtually" caffeine free. What that boild down to in actual numbers is that the amount of caffeine in decaf coffee is typicall between 0 mgs and 25 mgs. So the caffeine content is at least 75% less than the typical cup of reguar coffee, but it's helpful to be aware that the decaffeinating process can still leave a little residual caffeine in the coffee beans.
As a coffee lover and blogger, myself, I would find it difficult to start my day without a hot cup of freshly brewed coffee. Objectively speaking, though, limiting caffeine consumption--or avoiding it altogether--is a decision that probably correct for a certain percentage of the population.