Each day, billions of people rely on caffeine to wake up, or to get through that night shift or an afternoon slump.
In fact, this natural stimulant is one of the most commonly used ingredients in the world (1).
Caffeine is often talked about for its negative effects on sleep and anxiety.
However, studies also report that it has various health benefits.
This article examines the latest research on caffeine and your health.
Caffeine is a natural stimulant most commonly found in tea, coffee, and cacao plants.
It works by stimulating the brain and central nervous system, helping you stay alert and prevent the onset of tiredness.
Historians track the first brewed tea as far back as 2737 B.C. (1).
Coffee was reportedly discovered many years later by an Ethiopian shepherd who noticed the extra energy it gave his goats.
Caffeinated soft drinks hit the market in the late 1800s and energy drinks soon followed.
Nowadays, 80% of the world’s population consumes a caffeinated product each day, and this number goes up to 90% for adults in North America (1).
Caffeine is a natural stimulant that’s widely consumed worldwide. It helps you stay awake and can stave off tiredness.
Once consumed, caffeine is quickly absorbed from the gut into the bloodstream.
From there, it travels to the liver and is broken down into compounds that can affect the function of various organs.
That said, caffeine’s main effect is on the brain.
It functions by blocking the effects of adenosine, which is a neurotransmitter that relaxes the brain and makes you feel tired (
Normally, adenosine levels build up over the day, making you increasingly more tired and causing you to want to go to sleep.
It may also increase blood adrenaline levels and increase brain activity of the neurotransmitters dopamine and norepinephrine (
This combination further stimulates the brain and promotes a state of arousal, alertness, and focus. Because it affects your brain, caffeine is often referred to as a psychoactive drug.
Additionally, caffeine tends to exert its effects quickly.
Caffeine’s main effect is on the brain. It stimulates the brain by blocking the effects of the neurotransmitter adenosine.
Caffeine is naturally found in the seeds, nuts, or leaves of certain plants.
These natural sources are then harvested and processed to produce caffeinated foods and beverages.
- Espresso: 240–720 mg
- Coffee: 102–200 mg
- Yerba mate: 65–130 mg
- Energy drinks: 50–160 mg
- Brewed tea: 40–120 mg
- Soft drinks: 20–40 mg
- Decaffeinated coffee: 3–12 mg
- Cocoa beverage: 2–7 mg
- Chocolate milk: 2–7 mg
You can also find caffeine in some prescription or over-the-counter drugs like cold, allergy, and pain medications. It’s also a common ingredient in weight loss supplements.
Caffeine is most commonly found in coffee, tea, soft drinks, chocolate, and energy drinks.
Caffeine has the ability to block the brain-signaling molecule adenosine.
This change in brain messaging is thought to benefit your mood and brain function.
One review reports that after participants ingested 37.5–450 mg of caffeine, they had improved alertness, short-term recall, and reaction time (1).
In addition, a study linked drinking 2–3 cups of caffeinated coffee (providing about 200–300 mg caffeine) per day to a 45% lower risk of suicide (7).
Another study reported a 13% lower risk of depression in caffeine consumers (8).
When it comes to mood, more caffeine isn’t necessarily better.
A study found that a second cup of coffee produced no further benefits unless it was consumed at least 8 hours after the first cup (
It’s important to note that coffee and tea contain other bioactive compounds (besides caffeine) that may also be beneficial.
Caffeine may improve mood, decrease the likelihood of depression, stimulate brain function, and protect against Alzheimer’s and Parkinson’s disease.
Practically speaking, consuming 300 mg of caffeine per day may allow you to burn an extra 79 calories daily (17).
This amount may seem small, but it’s similar to the calorie excess responsible for the average yearly weight gain of 2.2 pounds (1 kg) in Americans (
However, a 12-year study on caffeine and weight gain noted that the participants who drank the most coffee were, on average, only 0.8–1.1 pounds (0.4–0.5 kg) lighter at the end of the study (
Caffeine may boost metabolism and promote fat loss, but these effects are likely to remain small over the long term.
When it comes to exercise, caffeine may increase the use of fat as fuel.
Caffeine may also improve muscle contractions and increase tolerance to fatigue (1).
Doses as low as 1.4 mg per pound (3 mg per kg) of body weight may be sufficient to reap the benefits (23).
Finally, it may also reduce perceived exertion during exercise by up to 5.6%, which can make workouts feel easier (25).
Consuming small amounts of caffeine about an hour before exercise is likely to improve exercise performance.
In fact, evidence shows a 16–18% lower risk of heart disease in men and women who drink between 1–4 cups of coffee daily (providing approximately 100–400 mg of caffeine) (29).
One thing to keep in mind is that caffeine may slightly raise blood pressure in some people. However, this effect is generally small (3–4 mmHg) and tends to fade for most individuals when they consume coffee regularly (32, 33,
It may also protect against diabetes.
A review noted that those who drink the most coffee have up to a 29% lower risk of developing type 2 diabetes. Similarly, those who consume the most caffeine have up to a 30% lower risk (36).
The authors observed that the risk drops by 12–14% for every 200 mg of caffeine consumed (36).
Caffeinated beverages like coffee and tea may reduce the risk of heart disease and type 2 diabetes, although this may depend on the individual.
Coffee consumption is linked to several other health benefits:
- Liver protection. Coffee may reduce the risk of liver damage (cirrhosis) by as much as 84%. It may slow disease progression, improve treatment response, and lower the risk of premature death (37, 38).
- Longevity. Drinking coffee may decrease the risk of premature death by as much as 30%, especially for women and people with diabetes (
- Decreased cancer risk. Drinking 2–4 cups of coffee per day may reduce liver cancer risk by up to 64% and colorectal cancer risk by up to 38% (41, 42, 43,
- Skin protection. Consuming 4 or more cups of caffeinated coffee per day may lower the risk of skin cancer by 20% (
- Reduced MS risk. Coffee drinkers may have up to a 30% lower risk of developing multiple sclerosis (MS). However, not all studies agree (48,
- Gout prevention. Regularly drinking 4 cups of coffee per day may reduce the risk of developing gout by 40% in men and 57% in women (
- Gut health. Consuming 3 cups of coffee a day for as few as 3 weeks may increase the amount and activity of beneficial gut bacteria (
Keep in mind that coffee also contains other substances that improve health. Some benefits listed above may be caused by substances other than caffeine.
Drinking coffee may promote a healthy liver, skin, and digestive tract. It may also prolong life and help prevent several diseases.
Caffeine consumption is generally considered safe, although habit forming.
Caffeine can also interact with some medications.
Individuals taking the muscle relaxant Zanaflex or the antidepressant Luvox should avoid caffeine because these drugs can increase their effects (
Caffeine can have negative side effects in some people, including anxiety, restlessness, and trouble sleeping.
Both the U.S. Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) consider a daily intake of 400 mg of caffeine to be safe. This amounts to 2–4 cups of coffee per day (
That said, it’s worth noting that fatal overdoses have been reported with single doses of 500 mg of caffeine.
According to the American College of Obstetricians and Gynecologists, pregnant women should limit their daily intake to 200 mg (
A caffeine intake of 200 mg per dose, and up to 400 mg per day, is generally considered safe. Pregnant women should limit their daily intake to 200 mg or less.
Caffeine isn’t as unhealthy as it was once believed.
In fact, evidence shows that it may be just the opposite.
Therefore, it’s safe to consider your daily cup of coffee or tea as an enjoyable way to promote good health.