Sweet Stimulation

How much caffeine is too much?

We've all done it: lacking energy for that afternoon ride, or trying not to fall asleep at work, we reach for an energy drink. Sure, it beats that pesky sleepiness into submission and keeps us upbeat and alert for another hour or two…but is it really worth it?

Monster, Rockstar, Red Bull, AMP, and 5-Hour Energy all claim to boost energy levels and enhance endurance with a combination of caffeine, taurine, guarana, and B-vitamins. However, according to many studies, there is limited evidence that these drinks significantly improve physical and mental performance. The caffeine in a single serving (8-12 ounces) can range from 70mg to 150mg; however, most cans contain two to three servings, tripling the caffeine intake to as much as 450mg per bottle. In comparison, one cup of coffee has about 95mg of caffeine.

Moderate caffeine intake is generally safe, but two or more servings in a single day can increase nervousness, irritability, sleeplessness, urination, and abnormal heart rhythms—especially in teenagers and nursing women. In addition, energy drinks typically contain high amounts of sugar, extra calories, and little nutritional value.

Some evidence suggests (but does not prove) that taurine boosts metabolism, which is one reason many consumers believe it could help them lose weight by burning calories faster. Unfortunately, this may also persuade people to substitute energy drinks for exercise and physical activity, thereby supporting and adding to the billion-dollar weight-loss industry.

The timing of consumption is also under study. For example, researchers have found that having caffeine alone before heavy exercise is safe, but the jury is still out regarding combining caffeine with certain herbal ingredients prior to exercise. Combining energy drinks and alcohol, such as the popular vodka and Red Bull, slows motor coordination and reaction times just as much as alcohol alone. Additionally, a person may unknowingly overlook the side effects of intoxication and other symptoms because the sensation of alertness is increased.

The bottom line is that moderation is the key. Though one energy drink a day is typically safe for the majority of the population, getting enough sleep, drinking plenty of water, and eating healthy meals will provide the best source of energy.

Drink Serving (oz) Servings per bottle/can Sugar (grams) Caffeine (mg) Calories
AMP 8 2 29 70 110
Red Bull 8 1 27 80 110
Rockstar 8 2 30 80 130
Moster Energy XXL 8 3 27 80 100
5-Hour Energy 2 1 0 75 4
Brewed Coffee 8 1 0 95 2


Alicia is a registered dietetic technician and has her BS in Food & Nutrition from MSU.