Let’s say you wake up every morning with a cup of coffee, tea, or soda in hand, relying on that familiar jolt of caffeine to jumpstart your day.
But have you ever asked yourself:
How much caffeine did you actually consume?
Is it OK to have that second cup?
Do you notice any differences in how you feel before and after your caffeine fix—whether it’s a sense of calm, happiness, or just feeling more awake?
I started pondering these questions after my husband mentioned last week that he didn’t feel the need for a second cup of coffee on Friday when he indulged in a Starbucks ‘Grande’ 16 oz coffee instead of his usual office machine brew. Curious, I dove into the world of caffeine consumption.
This post is also dedicated to a couple of my students who power through their busy weeks with energy drinks, chocolate protein shakes, and Starbucks coffee brimming with espresso shots. I hope they reconsider their caffeine intake after reading this.
So, How Much Caffeine is Too Much?
The Mayo Clinic suggests that up to 400 milligrams (mg) of caffeine per day appears to be safe for most healthy adults. That’s roughly equivalent to:
Four cups of brewed coffee
Ten cans of cola
Two energy shot drinks
For pregnant women, the American College of Obstetricians and Gynecologists recommends keeping caffeine intake below 200 mg/day.
So, for a healthy, non-pregnant adult, are four cups of brewed coffee really okay?
Well, not so fast.
According to the Center for Science in the Public Interest (CSPI), caffeine content can vary significantly across different beverages and brands. In other words, not all coffees are created equal. The caffeine in Starbucks Coffee isn’t the same as that in Dunkin, Blue Bottle, Folgers, or Maxwell House.
Caffeine Content: It’s All in the Details
The Food and Drug Administration (FDA) notes that the caffeine content in brewed beverages can fluctuate depending on factors like where the coffee beans or tea leaves were grown and processed, how the beverage is prepared, the type of coffee bean, roast style, and serving size.
Here’s a quick comparison:
Dunkin' Donuts Coffee (20 oz): About 400 mg of caffeine
Starbucks Coffee Blonde Roast (16 oz): 360 mg
Brewed Green or Black Tea (16 oz): 80 mg
Decaf Coffee (8 oz): 2-15 mg
No wonder my husband didn’t need another cup—his daily caffeine intake was already maxed out with that one Grande Starbucks coffee.
Sodas, Energy Drinks, and More: Caffeine Is Everywhere
Like coffee and tea, sodas and energy drinks also vary widely in caffeine content. Here’s what you might find in your favorite drinks:
Pepsi Zero Sugar (10 oz): 75 mg
Diet Coke (10 oz): 23 mg
5-hour Energy (2 oz): 200 mg
Red Bull (8.4 oz): 80 mg
Many nutritional or fitness shakes are also loaded with caffeine. For example:
Ensure Mocha (8 oz): 100 mg
Kellogg’s Cappuccino Protein Shake (10 oz): 100 mg
Vitaminwater Energy Tropical Citrus (20 oz): 50 mg
Odwalla Chai Vanilla Protein Shake (12 oz): 50 mg
Even energy snacks like Clif Shot Energy Gel, Awake Caffeinated Chocolate, and Gu Energy Gels pack a caffeinated punch. If you’re indulging in coffee-flavored ice cream, coffee yogurts, or chocolate drinks, you’re likely consuming about the same amount of caffeine as in a cup of tea.
Should You Rethink Your Caffeine Habit?
Everyone’s tolerance to caffeine varies. If you experience migraines, headaches, upset stomachs, rapid heartbeats, muscle tremors, jitters, or insomnia, it might be time to cut back on caffeine. Additionally, it's essential to consider that caffeine can linger in your system longer than you think—up to 10 hours for some individuals.
Interestingly, between chocolate, soda, and chocolate milk, our kids (ages 2-19) are consuming far more caffeine than they did 40-50 years ago, albeit in smaller doses. As they grow older, they’ll likely add coffee and tea to the mix, increasing their overall caffeine intake. It’s crucial for us to understand the effects of caffeine on our bodies, especially considering the younger generations.
Caffeine is water- and lipid-soluble, easily crosses the blood-brain barrier, and can be found in all body fluids. While it can increase alertness and wakefulness, excessive consumption can lead to elevated blood pressure and increased heart rate. Excess caffeine consumption is increasingly recognized as potentially harmful, even at doses that were previously considered safe.
Alcohol and Caffeine: A Dangerous Mix
Mixing alcohol with caffeine is particularly dangerous. Caffeine can mask the depressant effects of alcohol, leading you to drink more than you realize, increasing the risk of alcohol poisoning and other alcohol-related injuries. Products that tout pure or highly concentrated caffeine in powder or liquid forms should be avoided entirely. The FDA has issued warnings against these products due to their potential for misuse and overdose.
A Closer Look at the Experts
Center for Science in the Public Interest (CSPI) - Founded in 1971, the CSPI is one of the oldest independent, science-based consumer advocacy organizations. It provides practical advice on nutrition, food safety, and health to consumers. Talk show host Oprah Winfrey called their Nutrition Action Health Letter "the master-mind critic that sounded the food alarms." You can sign up for their free health tips on their website.
Food & Drug Administration (FDA) - The FDA is responsible for protecting public health by ensuring the safety, efficacy, and security of human and veterinary drugs, biological products, and medical devices. It also ensures the safety of the nation’s food supply, cosmetics, and products that emit radiation.
Mayo Clinic - The Mayo Clinic is a nonprofit organization committed to clinical practice, education, and research, providing expert, whole-person care to everyone in need of healing.
The Bottom Line
Understanding your caffeine consumption is key to managing its effects on your health. The next time you reach for that extra cup of coffee, soda, or energy drink, take a moment to consider how much caffeine you’ve already had—and whether you really need that extra boost. By being mindful of your caffeine intake, you can enjoy the benefits without experiencing the downsides.