The Mayo Clinic says most healthy adults can safely consume up to 400 mg of caffeine each day.
Caffeine is a central nervous system
stimulant that makes us feel alert. It can also
improve our mood and is associated with a reduced risk of
depression. It can also increase our adrenaline level, which can
leave us more irritable, anxious, and far more
emotionally-charged. Caffeine has been shown to improve certain
types of memory in some, but not all studies. Controlled amounts of caffeine can boost notable
performance gains for athletes. Some studies also
indicate caffeine is effective to increase long term memories.
Although ingesting too much caffeine makes it difficult to focus
There is some evidence that caffeine, when combined with certain
pain-relieving medications like acetaminophen, the main active
ingredient in Tylenol, and aspirin, helps those medications take
effect quicker, last longer, and increases their effects. Excedrin contains caffeine.
Here are a few common
sources of caffeine:
Most 12-ounce cups of coffee contain 90 to 120 mg of caffeine,
One 12-ounce cup of Starbucks contains about 260 mg,
Dunkin Donuts has 215 mg,
One 2-ounce shot of 5 hour energy contains about 215 mg,
One 12-ounce cup of McDonald's coffee has about 109 mg,
One 8-ounce can of Red Bull contains 80 mg,
One cup of brewed black tea contains about 67 mg,
One shot of espresso contains about 71 mg, (a latte is espresso
plus steamed milk - cappuccino is espresso plus milk and foam),
One 12-ounce can of diet Coke has 46 grams of caffeine,
One 12-ounce can of regular Coke has 34 grams of caffeine.