Caffeine 101: The Proven Health Benefits, How to Find It, and How Much Is Too Much

You’re probably most familiar with caffeine from the java jolt you get from your coffee. It’s best described as a bitter substance that’s present in more than 60 plants, according to the U.S. National Library of Medicine. But that’s just the official definition. For so many people, caffeine is what wakes them up and gets them going in the morning. Indeed, it’s a psychoactive stimulant that acts on your central nervous system to drive your energy up. (1)

After you consume caffeine, it’s absorbed into your bloodstream, where levels peak in as little as 15 minutes; later,the livertakes over in eliminating caffeine. (2)

While you may pour yourself endless cups ofcoffeeto survive the morning, the Mayo Clinic notes that drinking 400 milligrams (mg) of caffeine a day is safe for healthy adults. (3) They note that this is the equivalent to four cups of coffee per day, but that all depends on where your coffee comes from. For instance:

• Standard brewed 8-ounce (oz) cup of coffee: 95 mg caffeine (4)
• Standard instant 8-oz cup of coffee: 62 mg caffeine (5)
• Starbucks blonde roast, 8 oz (short): 180 mg caffeine (6)
• Starbucks blonde roast, 16 oz (grande): 360 mg caffeine (6)
• Starbucks iced coffee, 16 oz (grande): 190 mg caffeine (7)
• Coffee brewed from Keurig, 8-oz cup: between 75 and 150 mg caffeine, depending in part on roasting strength (8)

As you can see, to stay within the safe limit, you should investigate just how much caffeine your specific brew contains. And, if you’re looking to cut down on caffeine, the first step is to reduce your coffee intake, as it’s the most widely consumed source of caffeine, research shows. (9)

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

TeaWhile most herbal teas (like chamomile) are caffeine-free, others contain varying amounts. (10) For instance, green contains 25 to 29 mg per cup, while black racks up more, with 25 to 48 mg per cup. (11)

DecafDecaf coffees and teas will have minimal amounts of caffeine, about 2 to 5 mg. (11)

ChocolateCocoa naturally contains caffeine. One oz ofdark chocolateoffers 12 mg. (12)

Chocolate Ice CreamThis treat also has minimal amounts of caffeine, about 4 mg per 1-cup serving. (13)

Energy DrinksA 8.4-oz can of Red Bull contains 80 mg, while a 16-oz can of Monster contains 160 mg. (14,15)

ColaOne 16-oz can has 44 mg. (16)

Caffeinated WaterIn this instance, caffeine is added to the mix. One variety, the apple-pear flavor by Hint, contains 60 mg of caffeine per 16-oz bottle. (17)

Migraine MedicationSome over-the-countermigraine drugscontain a combo of pain relieversacetaminophen,aspirin, and caffeine (65 mg per tablet). That said, too much caffeine can actually causeheadaches, so watch the amount you consume from other sources. (18)

People often talk about drinking coffee as being a guilty pleasure or a bad habit, namely because of the caffeine. But it doesn’t just perk you up, it also can be a major perk for your health. The breadth of the research is on how coffee affects health, rather than caffeine alone. While it’s true that coffee does contain other beneficial compounds (like chlorogenic acid and antioxidants), it’s also the most widely consumed source of caffeine.

In fact, 80 percent of caffeine is knocked back as coffee. (19)

As long as you’re drinking your coffee black or with a hit of milk (rather than sugary syrups), it’s also a healthy way to get caffeine, according tothe U.S. Department of Agriculture'sMyPlateguidelines。如果你想了解多么哟ur caffeine habit may be shaping your health, you’ve got to look at the coffee research. Here’s a look into just what it may do, based on observational research.

Just keep in mind that while these studies suggest a link between drinking coffee and the health benefit, this does not indicate a definite cause-and-effect relationship:

Boost Brain HealthWhen people consumed 200 mg of caffeine after studying images, their memories were enhanced for up to 24 hours later, giving credence to the idea that caffeine can shore up long-term memory, according to a study published in January 2014 in the journalNature Neuroscience.(20)

Safeguard Your HeartIn a study that looked at 185,855 people ages 45 to 75 — including African-Americans, Native Hawaiians, Japanese-Americans, Latinos, and whites — coffee drinkers who sipped two to three cups a day saw their risk of death due to conditions like heart disease and stroke drop by 18 percent compared with non-java drinkers, noted a study published in August 2017 in the journalAnnals of Internal Medicine。(21)

Help You in the GymWhen caffeine breaks down, it turns into a few compounds that affect blood flow, fat burning, and oxygen capacity, notes the American Council on Exercise (ACE). (22) 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 the exercise challenge. In fact, ACE cites research showing that a small, 6- to 8-oz cup of a caffeinated beverage may be beneficial.

Protect Against CancerA review published in November 2017 in the journalBMJlooked at 201 meta-analyses and found that drinking coffee was associated with an 18 percent lower risk of cancer. The authors recommend sticking to three to four cups of coffee a day. Specifically, they found that coffee can decrease the odds ofprostate cancer, endometrial cancer,melanoma, nonmelanomaskin cancer, and liver cancer. Why? Coffee is rich in disease-fighting and anti-inflammatory antioxidants, and caffeine also has antioxidant properties. (23)

Prevent DiabetesIf you drink coffee here and there, you may consider boosting your brew. In a study published in April 2014 in the journalDiabetologia, men and women who increased their coffee consumption by 1.5 cups a day benefited from a 11 percent lower risk of type 2 diabetes over a four-year period compared with those who didn’t start sipping more. On the other hand, those who dropped two cups a day had a 17 percent higher risk of the disease. While that sounds promising, senior author Frank Hu noted that other lifestyle measures are likely more important than coffee (or caffeine) alone. “But coffee is only one of many factors that influencediabetes risk。More importantly, individuals should watch their weight and be physically active,” he said in a press release. (24)

Delay DementiaWhile research isn’t conclusive that coffee or caffeine may prevent Alzheimer’s, it may help prevent those suffering from mild cognitive impairment from progressing to dementia, suggests a study published in 2012 in theJournal of Alzheimer’s Disease。(25)Those who developed dementia had 51 percent lower caffeine levels in their blood compared with those with MCI whose disease didn’t advance. Caffeine may interact with a component in coffee to increase levels of a growth factor that stymies Alzheimer’s progression, the authors note in a press release. Three cups of coffee is the ideal amount, they said. (26)

Stave Off DepressionIn one study, over 50,000 women who didn’t have depressive symptoms were followed for 10 years. Those who drank two to three cups of coffee a day had a 15 percent lower likelihood of suffering from depression compared with those who had less than a cup per week. The stimulant effect of caffeine may boost your sense of well-being and energy, the authors note. It may also play a role in releasing happy chemicals, likedopamineandserotonin。(19)

It was only recently that the World Health Organization took coffee off of its list of potentially carcinogenic foods, Harvard Health reports. (27) That’s certainly good news.

But remember that moderation is key when it comes to caffeine. Certainly, if you’re drinking too much, short-term side effects can includemigraines,insomnia, nervousness, irritability, restlessness,frequent urination, stomach upset, fast heartbeat, and muscle tremors, according to the Mayo Clinic. And, as they point out, 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. (3)

如果你想晚上睡好,know your limit with how late you should be drinking it. It takes six hours for your body to eliminate half of the caffeine you drank. (28) The risk is drinking it too late where it interferes with your sleep, then having to compensate the next day with more caffeine — it can be a difficult cycle to get out of. The thing is, caffeine can sap your sleep even if you drink it six hours before bed, research has shown. (29)

Another concern: If you’re pregnant. While the thought used to be that caffeine was off limits for pregnant women, it’s now recommended that they keep their caffeine intake to a certain limit to help avoid complications like preterm birth or low birth weight. (While the World Health Organization recommends below under 300 mg per day, recommendations vary.) (30) 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 is best to include in your diet.

And finally, if you have type 2 diabetes, that’s another time to check your caffeine intake. While it’s associated with a decreased risk for developing diabetes, it can be different story for people who already have the disease. Caffeine may impact insulin and increase or decrease blood sugar levels. (31) It’s always a good idea to talk to your doctor to see what’s best for you given your individual health concerns.