For more on the whole-body effects of caffeine, check out my podcast episode on FUELED Wellness + Nutrition.
Not only do I enjoy sipping a good cup of coffee, I also appreciate the slight edge of brain-boosting energy that it gives me.
I generally make the right choices when it comes to health and fitness: regular exercise, frequent small meals and snacks of energy-rich whole grains, lean proteins and healthy fats, along with a daily supplement regime and plenty of water.
So for me, any lack of energy is more about a lack of sleep. Even after juggling family and friends with work, there’s just so much that I want to do! In paring down my schedule, sleep is often the first thing to go.
To counter feelings of sluggishness, I often turn to caffeine. Clearly, I’m not alone. Caffeine is reported to be one of the most widely used drugs, with an estimated 80 percent to 90 percent of North American adults consuming caffeinated beverages every day.
Caffeine is a naturally occurring compound found in the leaves, seeds, or fruits of more than 60 plants, including coffee beans, cacao beans, and tea leaves.
Mechanism of Action
Caffeine stimulates the central nervous system, heart, muscles and areas of our brain that control blood pressure.
Fortunately, our daily habit isn’t so bad.
There are actually many benefits to moderate caffeine consumption. The most immediately noticeable is an increased sense of alertness.
And contrary to popular belief, caffeine won’t leave you dehydrated – at least not in the amount found in standard servings of coffee, tea or soft drinks.
Mental alertness. Caffeine seems to prevent a decline in alertness and cognitive capacity when consumed throughout the day. It appears to be especially effective in people who are not regular caffeine users. Drinking coffee containing caffeine 100 mg prior to a cognition test improves reaction times, both in people with recent poor sleep quality, and in those with adequate sleep.
Age-related cognitive decline. Population research from the Women’s Health Initiative found that caffeine intake of more than 175 mg daily (just under two cups of coffee) compared to less than 175 mg daily is associated with a 26% reduced risk of developing dementia or cognitive impairment in postmenopausal women.
Memory. Taking caffeine 65-200 mg orally daily has been shown to improve memory function.
Athletic performance. Caffeine is well-documented as a performance enhancer, particularly for endurance athletes. It has been shown to decrease perceived levels of exertion, which enables the athlete to feel less tired and increase their performance.
Caffeine appears to help our bodies use fat for energy more effectively during exercise, thus sparing our carbohydrate stores and delaying fatigue.
It may also benefit performance in short bouts of high-intensity exercise, such as sprints or strength training. One theory is that as a central nervous system stimulant, caffeine buffers our perception of pain and perceived exertion, allowing us to work harder.
Overall, caffeine appears to modestly improve muscle strength and physical endurance. The degree of improvement often depends on the timing of caffeine intake and the level of exertion required by the activity.
Typical dose recommended is approximately 1mg to 5 mg per pound; keep in mind that doses in excess of 800 mg per day can result in urine levels greater than the 15 mcg/mL allowed by the National Collegiate Athletic Association.
Pain. Clinical research shows that taking caffeine in combination with acetaminophen, propyphenazone, ibuprofen, or other pain-relieving agents can reduce acute pain compared to the effects of pain-relieving agents alone
Migraine or tension headache. Taking caffeine orally in combination with acetaminophen, aspirin, and/or sumatriptan is effective for treating migraine headache
Diabetes. Total caffeine consumption from beverages such as coffee or tea is associated with a lower risk of developing type 2 diabetes. This effect appears to be dose-dependent. For example, an increase of 200 mg/day caffeine intake seems to be associated with a 14% decrease in the incidence of type 2 diabetes. Additionally, in American men, consuming caffeine 417 mg/day from coffee or tea is associated with a 20% lower risk of developing type 2 diabetes compared to men consuming less than 37 mg/day.
Although caffeine seems to be involved with decreasing the risk of developing type 2 diabetes, it may not be effective in treating type 2 diabetes.
Gallbladder disease. Consumption of caffeinated beverages that provide 400 mg or greater of caffeine per day is associated with a significantly reduced risk of developing symptomatic gallstone disease.
Parkinson disease. There is some evidence from large-scale epidemiological studies that suggests people who consume caffeinated beverages, such as coffee, tea, and cola, have a decreased risk of Parkinson disease.
Drawbacks of caffeine
It’s not all good news, though. While caffeine in moderate doses is typically well tolerated in adults and children, we know that too much caffeine can leave us feeling restless and irritable and can interfere with sleep. And we can become dependent on it, becoming foggy or getting headaches without our usual fix.
Caffeine can exacerbate existing conditions such as hypertension, anxiety, irritable bowel syndrome (IBS), and bipolar disorder. When it comes to bone health, research is mixed. Caffeine can increase urinary excretion of calcium, although it usually remains within the normal range. In some studies, higher caffeine intake is associated with decreased bone mineral density, though other population research shows that caffeine intake is not associated with decreased bone density.
Even in otherwise healthy people, too much caffeine can cause insomnia, increased heart rate, tremors, ringing the ears, nervousness, restlessness, GI upset and nausea.
And, no surprise, chronic use of caffeine, especially in large amounts, can result in psychological and physiological dependence.
How much is safe?
Moderate intake of caffeine appears to be just fine for the majority of the population, with most health organizations defining “moderate” as not more than 200 to 300 milligrams per day. You may, however, want to talk with your physician to determine what’s best for you.
US Dietary Guidelines Advisory Committee states that there is strong and consistent evidence that consumption of caffeine 400 mg daily (about what you get in four cups of coffee) is not associated with increased risk of major chronic diseases, such as cardiovascular disease or cancer, in healthy adults.
Even pregnant women don’t have to nix caffeine entirely: The American College of Obstetricians and Gynecologists says that expecting mothers can safely have up to 200 mg of caffeine daily (about two small cups of coffee, depending on the strength of the brew)
American College of Pediatrics recommends that kids under the age of 12 avoid caffeine altogether, and kids 12-18 to limit caffeine not more than 85-100 mg
Keep in mind that only the amount of added caffeine must be stated on product labels. The amount of caffeine from caffeine-containing natural ingredients such as coffee or green tea does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.
Acute use of high doses, typically above 400 mg daily, has been associated with significant adverse effects such as increased heart rate and sleep disturbances
Dialing back our caffeine intake
If you decide that you need to curb your caffeine intake, a few tips can make the transition easier.
Start by tracking how much caffeine you’re getting daily from foods and drinks. Remember to count medications and supplements as well. Cut back gradually to minimize withdrawal, aiming to consume one less serving every day or two until you achieve your goal of moderate caffeine consumption.
If you find it difficult to cut back, go half-and-half, incorporating decaffeinated coffee, tea, or soft drinks along with the fully loaded versions. You can also substitute decaffeinated herbal tea or steep your usual tea for less time to lessen the caffeine content.
Turn to other natural energy boosters, such as exercise. Even a short, brisk walk can boost alertness. Eat small meals and snacks every three or four hours throughout the day, and avoid high-fat meals, which can leave you feeling sluggish and tired.
And finally, get a good night’s sleep.
Caffeine content of common products
- Black tea, 8 oz: 47 mg
- Black tea, decaf, 8 oz: 2 mg
- Coffee, brewed, generic, 8 oz: 95 mg
- Coffee, decaf, brewed, generic, 8 oz: 2 mg
- Espresso, 1 oz: 64 mg
- Starbucks brewed coffee, 16 oz: 330 mg
- Coke and Coke Zero, 12 oz: 35 mg
- Diet Coke, 12 oz: 46 mg
- Mountain Dew, regular or diet, 12 oz: 55 mg
- Red Bull, 8.4 oz: 80 mg
- Chocolate milk, 8 oz: 5 mg
- Hershey’s milk chocolate bar, 1.55 oz: 9 mg
- Hershey’s special dark chocolate bar, 1.45 oz: 31 mg
- Excedrin, extra strength, one tablet: 65 mg
- Vivarin, one tablet: 200 mg
Information obtained from the USDA National Nutrient Database, Center for Science in the Public Interest and product labels and websites.Molly Kimball, RD, CSSD is a registered dietitian + nutrition journalist in New Orleans, and founder of Ochsner’s Eat Fit nonprofit initiative. Tune in to her podcast, FUELED | Wellness + Nutrition and follow her on Facebook, Instagram and Twitter at @MollyKimballRD.