Caffeine 101: Health Benefits, Risks, and Sources
Diet & NutritionBeverages

Caffeine 101: Health Benefits, Risks, and Sources

Caffeine 101: Health Benefits, Risks, and Sources
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Updated on November 1, 2022
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You’re probably most familiar with caffeine from the jolt you get from your morning coffee. It’s best described as a bitter substance that’s present in more than 60 plants,

 but that’s just the official definition. While caffeine is what gets many people going in the morning, it can have a slew of other health benefits.
Caffeine is a psychoactive stimulant that affects your brain and acts on your central nervous system to drive up your energy. After you consume caffeine, it’s absorbed into your bloodstream, where levels usually peak in 30 to 60 minutes (though the peak can happen in as little as 15 minutes or as long as 120 minutes, depending on the individual).

 Later, the liver takes over in eliminating caffeine.

When Is the Best Time of Day to Drink Coffee?

These expert tips will help you time your morning joe to maximize energy without impacting sleep.
When Is the Best Time of Day to Drink Coffee?

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How Much Caffeine Is Safe to Drink per Day?

While you may want to pour yourself endless cups of coffee to survive the morning, 400 milligrams (mg) of caffeine a day is the recommended safe limit for healthy adults.

 That’s equivalent to about four mugs of coffee per day — but it all depends on where your coffee comes from.
  • Standard brewed coffee, 8 ounces (oz): 95 to 200 mg caffeine

  • Starbucks medium roast (Pike Place), 8 oz: 155 to 195 mg caffeine

  • Dunkin’ coffee, 10 oz: 180 mg caffeine, depending on the equipment used and the steeping method

  • Coffee brewed from a Keurig, 8 oz: 75 and 150 mg caffeine, depending on the roasting strength

As you can see, to stay within the safe limit, you should investigate just how much caffeine your specific drink of choice contains. If you’re a coffee drinker — the most widely consumed source of caffeine — a good first step is to reduce your coffee intake.

Where Caffeine Is Found: Exploring the Best Sources

Though the chatter is always on coffee, caffeine is found in many other sources:

  • Tea While most herbal teas (like chamomile) are caffeine-free, others contain varying amounts. For instance, brewed green tea contains about 29 mg per cup, while brewed black tea racks up more, with about 48 mg per cup.

  • Decaf Decaf coffees and teas have minimal amounts of caffeine, about 2 mg.

  • Chocolate Cocoa naturally contains caffeine. A single ounce of dark chocolate (70 to 85 percent cacao solids) offers 22.7 mg.

  • Chocolate Ice Cream This treat also has minimal amounts of caffeine, about 4 mg in 1 cup.

  • Energy Drinks An energy drink has between 70 to 100 mg of caffeine in 8 oz.

     However, most energy drinks are 12 to 24 oz, and can have 150 to 300 mg of caffeine per can.
  • Cola One can (12 oz) has 35 to 45 mg caffeine.

  • Migraine Medication Some over-the-counter migraine drugs contain a combo of pain relievers like acetaminophen (Tylenol) and aspirin along with caffeine (65 mg per tablet).

     That said, too much caffeine can actually cause headaches, so watch the amount you consume from other sources.
illustrative graphic titled, Top Sources of Caffeine That Arent Coffee the illustrated icons include cola, tea, chocolate, energy drink, chocolate ice cream, decaf coffee. the Everyday Health logo is located bottom left corner
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What Are the Potential Health Benefits of Caffeine?

People sometimes talk about drinking coffee as a guilty pleasure or a bad habit, namely because of the caffeine. But along with perking you up, caffeine intake may be a major perk for your health. Given coffee’s popularity as the go-to source of caffeine, most research is done on how coffee affects health, rather than the benefits of caffeine alone.

While it’s true that coffee contains other beneficial compounds (like chlorogenic acid and antioxidants), coffee is also the most widely consumed source of caffeine.

 In fact, according to a report published in 2022 that surveyed almost 27,000 active-duty U.S. military personnel, coffee accounted for 68 percent of their caffeine intake, with the rest coming from soda, tea, and energy drinks.

As long as you’re drinking your daily coffee black or with a splash of milk (rather than loading up with sugary syrups), it’s also a healthy way to get caffeine.

Here’s how your caffeine habit may actually support your health:

Boost Brain Health When people consumed 200 mg of caffeine after studying images, their memories were enhanced for up to 24 hours, giving credence to the idea that caffeine can shore up long-term memory, according to a study from 2014. (20) However, there are a lot of nuances when it comes to just how caffeine consumption can boost your brain, and a review published in 2021 of recent studies suggests that more research is needed.

Safeguard Your Heart A study that included over 40,000 U.S. adults who drank coffee in the morning found that their risk of death due to conditions like heart disease dropped by 31 percent compared with noncoffee drinkers.

Help You in the Gym When caffeine breaks down, it turns into a few compounds that affect blood flow, fat burning,

 and oxygen capacity.

 You may find that drinking a small cup before going to the gym (especially in the morning) can make you feel more energetic and ready to tackle an exercise challenge. In fact, research shows that consuming about 3 to 6 mg per kilogram of body weight of caffeine about 60 minutes before your workout may be beneficial.

Protect Against Cancer Coffee may decrease the odds of liver and endometrial cancer, and may help protect against skin, colon, oral, and prostate cancer, according to the American Institute for Cancer Research and the World Cancer Research Fund. Why? Coffee is rich in disease-fighting and anti-inflammatory antioxidants, and caffeine also has antioxidant properties.

Reduce the Risk of Diabetes A number of studies over the past few decades have examined whether drinking coffee may help prevent or manage type 2 diabetes. Authors of a meta-analysis published in 2021 found a robust association between coffee consumption and a reduced risk of type 2 diabetes. Specifically, the authors note that higher consumption seems to align with lower diabetes risk and that long-term coffee consumption helped maintain proper liver function, which improved metabolic control and could correlate to a reduced diabetes risk. But the authors caution that a direct cause-and-effect relationship between drinking coffee and preventing diabetes is lacking.

Delay Dementia While research isn’t conclusive that coffee or caffeine can prevent Alzheimer’s, it may help those who experience mild cognitive impairment from progressing to dementia. One study from Australia tracked 227 adults for more than 10 years, using brain imaging and other tests at regular intervals to monitor cognitive response. The authors report that higher coffee consumption correlated to slower cognitive decline.

Stave Off Depression One meta-analysis of 29 studies found that an increased intake of 240 ml of coffee per day (about 8 oz) helped reduce depression risk by 4 percent. Additionally, drinking more than three cups of caffeinated coffee daily during the one to two years postpartum may help lower the risk of postpartum depression.

 It may also play a role in releasing happy chemicals like dopamine and serotonin.

What Are the Possible Health Risks of Caffeine?

In 2016, the World Health Organization took coffee off its list of potentially carcinogenic foods.

But remember that moderation is key when it comes to caffeine. Certainly, if you’re drinking too much, short-term side effects can include migraines, insomnia, nervousness, irritability, restlessness, frequent urination, stomach upset, fast heartbeat, and muscle tremors.

 And everyone reacts to it differently. It’s important to learn how your body handles caffeine so that you can hit a sweet spot where it perks you up without causing problems.
Your sleep can be affected. If you want to sleep well at night, you need to know when to stop consuming caffeine during the day. It generally takes four to six hours for your body to eliminate half of the caffeine you drink, which may mean that drinking caffeine too late in the day could interfere with your sleep. Then the next day, you may compensate with more caffeine — leading to more sleep disruptions. You should avoid caffeine at least eight hours before bed to help boost sleep quality.

Caffeine consumption should be limited during pregnancy. While caffeine was once off-limits for pregnant women, it’s now recommended that they keep their intake to a certain limit to help avoid complications like preterm birth or low birth weight. The American College of Obstetricians and Gynecologists recommends less than 200 mg per day of caffeine.

 If you’re pregnant, the best course of action for you and your baby is to chat with your physician about how much (if any) caffeine to include in your diet.
Caffeine can impact insulin and blood sugar levels for those with type 2 diabetes. While caffeine is associated with a decreased risk for developing diabetes, it can be a different story for people who already have the disease.

 It’s always a good idea to talk to your doctor to see what’s best for you given your individual health concerns.

The Takeaway

  • The recommended safe limit for daily caffeine consumption is 400 mg, and this can come from coffee, tea, energy drinks, chocolate, and more.
  • Caffeine can have many health benefits, including supporting your brain and heart health, and helping boost your workouts.
  • However, too much caffeine can negatively impact sleep, and those who are pregnant or have certain medical conditions should work with their healthcare providers to figure out how much they should consume per day.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
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  9. Chocolate, dark, 70–85% cacao solids. U.S. Department of Agriculture FoodData Central. April 1, 2019.
  10. Ice Creams, Chocolate. U.S. Department of Agriculture FoodData Central. April 1, 2019.
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  13. Make Better Beverage Choices. U.S. Department of Agriculture MyPlate.
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  15. Wang X et al. Coffee Drinking Timing and Mortality in US Adults. European Heart Journal. February 21 2025.
  16. Antonio J et al. Common Questions and Misconceptions About Caffeine Supplementation: What Does the Scientific Evidence Really Show? Journal of the International Society of Sports Nutrition. March 11, 2024.
  17. Stadheim KH et al. Caffeine Increases Exercise Performance, Maximal Oxygen Uptake, and Oxygen Deficit in Elite Male Endurance Athletes. Medicine & Science in Sports & Exercise. November 1, 2021.
  18. Guest NS et al. International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance. Journal of the International Society of Sports Nutrition. January 2, 2021.
  19. Coffee and Cancer: What the Research Says. American Institute for Cancer Research. June 24, 2025.
  20. Kolb H et al. Coffee and Lower Risk of Type 2 Diabetes: Arguments for a Causal Relationship. Nutrients. March 31, 2021.
  21. Gardner SL et al. Higher Coffee Consumption Is Associated With Slower Cognitive Decline and Less Cerebral aβ-Amyloid Accumulation Over 126 Months: Data From the Australian Imaging, Biomarkers, and Lifestyle Study. Frontiers in Aging Neuroscience. November 18, 2021.
  22. Wang Y et al. Coffee and Caffeine Intake and Depression in Postpartum Women: A Cross-Sectional Study From the National Health and Nutrition Examination Survey 2007–2018. Frontiers in Psychology. February 16, 2023.
  23. The Latest Scoop on the Health Benefits of Coffee. Harvard Health Publishing. September 25, 2017.
  24. Caffeine and Sleep. Sleep Foundation. July 16, 2025.
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  26. Caffeine: Does It Affect Blood Sugar? Mayo Clinic. March 7, 2024.
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Karen E. Todd

Karen E. Todd, RD, CSCS, EP-C, CISSN

Medical Reviewer

Karen E. Todd, RD, CSCS, EP-C, CISSN, is a registered dietitian and strength and conditioning specialist committed to evidence-based education in lifelong wellness, sports nutrition, and healthy aging.

With more than 30 years of experience in nutritional education, dietary supplements, functional foods, and exercise performance, she specializes in nutrition and exercise performance communications, providing expert insights to both media and consumers. She serves as a nutrition communicator, speaker, spokesperson, and brand consultant, and currently works in nutraceutical ingredient innovation and development, focusing on how nutrients and ingredients support health, performance, and wellness across the lifespan.

Karen also runs TheSupplementDietitian.com, a free online resource dedicated to helping consumers navigate the world of dietary supplements. The site provides science-based education on how supplements are regulated, how to identify safe and effective products, and how to fill nutritional gaps when diet alone isn’t enough.

Her experience spans clinical nutrition, exercise performance, and product development, giving her a broad perspective on the scientific, practical, and regulatory considerations that shape the supplement and functional food industries. Karen is a contributing guest blogger for Psychology Today’s “Feed Your Brain” column, a scientific advisory board member for Agro Food Industry Hi Tech, and a board member for Council for Responsible Nutrition, a leading professional organization in the nutraceutical space.

She is widely recognized for her ability to translate complex research into clear, evidence-based insights that help students, practitioners, and consumers make informed decisions about nutrition and supplementation.

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Jessica Migala is a freelance writer with over 15 years of experience, specializing in health, nutrition, fitness, and beauty. She has written extensively about vision care, diabetes, dermatology, gastrointestinal health, cardiovascular health, cancer, pregnancy, and gynecology. She was previously an assistant editor at Prevention where she wrote monthly science-based beauty news items and feature stories.

She has contributed to more than 40 print and digital publications, including Cosmopolitan, O:The Oprah Magazine, Real Simple, Woman’s Day, Women’s Health, Fitness, Family Circle, Health, Prevention, Self, VICE, and more. Migala lives in the Chicago suburbs with her husband, two young boys, rescue beagle, and 15 fish. When not reporting, she likes running, bike rides, and a glass of wine (in moderation, of course).

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