Caffeine is a stimulant and the most commonly used drug in the world. Benefits can include increased alertness, energy, and concentration. However, it can also lead to insomnia and headaches.
Every day, millions consume caffeine to increase wakefulness, alleviate fatigue, and improve concentration and focus. Amid myths and controversy about whether caffeine is good or bad for us, evidence suggests that moderate coffee consumption can bring both benefits and risks.
However, excessive consumption of caffeine may not be healthy. In addition, the recent trend of adding caffeine to drinks and snacks that do not naturally contain it has raised new concerns.
Fast facts about caffeine
- Caffeine is a stimulant that occurs naturally in some foods.
- The Food and Drug Administration (FDA) recommends a maximum intake of 400 mg a day, or two to three cups of coffee.
- A moderate intake of coffee may enhance weight loss, cognitive function, and alertness.
- Caffeine may have a negative impact on pregnancy, fertility, glucose control, and other aspects of health.
- Energy drinks can contain high levels of caffeine but are unlikely to be hazardous unless consumed with alcohol.
- Caffeine powder can lead to a fatal overdose and should be avoided.
The Food and Drug Administration (FDA) considers caffeine to be both a drug and a food additive. They recommend a maximum daily intake of
In prescription and over-the-counter (OTC) medications, caffeine can help treat tiredness and drowsiness, as well as to enhance the effects of some pain relievers.
It belongs to a group of medications called central nervous system (CNS) stimulants. Foods containing caffeine can help restore mental alertness.
Caffeine’s use as an alertness aid should be for occasional use only, and does not replace sleep.
In the United States (U.S.), more than 90 percent of adults use caffeine regularly, with an average consumption of more than
Caffeine occurs naturally in the leaves, seeds, or fruit of more than 60 plant species, including:
- coffee beans
- tea leaves and buds
- dola nuts
- cacao beans
- guarana seeds
- yerba mate leaf
Caffeine in plants acts as a natural pesticide. It paralyzes and kills insects that attempt to feed on them.
Food sources
Caffeine features in tea, coffee, and chocolate, and it is regularly added to gum, candy, waffles, water, syrup, marshmallows, sunflower seeds, and other snacks.
The FDA recommends that healthy adults limit their caffeine intake to a maximum of
There is no set limit for children, but the American Academy of Pediatrics (AAP) discourages the consumption of caffeine and other stimulants by children and adolescents.
The amount of caffeine included in some common foods and beverages is:
- One 200 milliliter (mL) cup of coffee contains approximately 90 mg.
- One 250 mL energy drink is 80 mg.
- One 50 mL cup of black tea is 28 mg.
- One 200 mL cup of decaffeinated coffee contains around 7 mg.
Decaffeinated cola and soft drinks contain no caffeine, but decaffeinated coffee is not caffeine-free. “Energy drinks” contain varying amounts of caffeine. Decaffeinated coffee contains
Additional products are now appearing on the market, from “psyched up” oatmeal to “wired” waffles.
These have raised concerns, especially regarding the potential impact on children and adolescents. The FDA
Caffeine may have some health benefits, but not all of these have confirmation by research.
Weight loss
Caffeine may boost weight loss or prevent weight gain, possibly by:
- suppressing the appetite and temporarily reducing the desire to eat
- stimulating thermogenesis, so the body generates more heat and energy from digesting food
Weight loss products seen as thermogenics may contain caffeine and ephedra, or ephedrine. Further research is necessary, however, to confirm whether caffeine actually aids weight loss.
Alertness
Many people drink coffee in the morning due to its benefits of increasing attention and alertness. However, caffeine is not a substitute for sleep.
Sports performance
Research states that caffeine can improve athletic performance, including reaction time and agility. However, other studies suggest that caffeine can interfere with sleep quality, potentially affecting overall sports performance.
Brain function
Caffeine affects adenosine receptors in the brain. Coffee also contains polyphenol antioxidants, and these, too, act on various pathways.
Studies suggest that drinking coffee may help enhance certain thinking skills and slow the mental decline associated with aging. However, more research is necessary to confirm this.
Alzheimer’s disease and Parkinson’s disease
Memory
Skin cancer
Although the evidence limits to small clinical trials, caffeine shows promising results in preventing skin cancers and providing general sun protection. However, larger high quality studies are necessary.
Kidney stones
Research indicates that a moderate increase in caffeine links to a 5.32 percent lower risk of developing kidney stones.
Mouth, throat, and other cancers
Studies from the
Stroke
Type 2 diabetes
Coffee consumption may lower the risk of type 2 diabetes. This could be due to the antioxidant properties in coffee that can help prevent conditions resulting from inflammation in the body.
Much of the published research about caffeine suggests that it is beneficial, in moderation. However, some studies highlight the potentially harmful effects of caffeine.
- Depression: A high caffeine intake may worsen symptoms of anxiety and depression. However, whether caffeine leads to depression or depression causes people to consume more caffeine remains unclear.
- Blood sugar: People with type 2 diabetes report that their blood glucose levels
rise after consuming caffeine. There is some evidence that caffeine may impair insulin action, leading to a small but detectable rise in blood sugar levels, particularly after meals. - Pregnancy: Women should limit their caffeine intake to 200 mg or less during pregnancy. Studies suggest that caffeine may have particular impacts on the fetus, including:
- loss of pregnancy
- delayed fetal growth
- abnormal fetal heart rhythm
- Nursing: Caffeine passes into milk in small amounts, and it may build up in the nursing infant. Infants whose mothers consume large amounts of caffeinated beverages may exhibit jitteriness and experience difficulty sleeping.
- Incontinence: Caffeine can irritate the bladder, leading to incontinence or issues with passing urine.
- Insomnia: Consuming caffeine before bedtime
can significantly disrupt sleep, reducing objectively measured total sleep time by around 45 minutes. - Headaches: The links between caffeine and headaches are multidirectional; having caffeine can cause them, but withdrawal may also provoke them. Caffeine consumption may be a modest risk factor for triggering chronic daily headache, regardless of headache type.
- Menopause: Those who consume caffeine during menopause may be more prone to having hot flashes and night sweats.
Other adverse effects
Caffeine’s primary effect on the body is an increased temporary sense of wakefulness and alertness, but it can also cause uncomfortable side effects.
Consuming
- jitters and shakes
- disrupted sleep
- fast or uneven heartbeat
- high blood pressure
- headaches
- nervousness or anxiety
- dizziness
- dependency
- dehydration
- irritability
- heartburn
- stomach upset, diarrhea, and nausea
- muscle tremors
Drug interactions
Some medications may interact with caffeine.
These include some:
- antibiotics
- antipsychotics, such as clozapine
- diuretics
- beta-blockers
Several myths surround caffeine consumption.
1. Is caffeine addictive?
In 2013, the American Psychiatric Association (APA) added caffeine withdrawal to the list of recognized conditions in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR). However, not all caffeine consumers have withdrawal symptoms if they stop consuming caffeine.
People who suddenly stop drinking coffee may experience symptoms about 12 to 24 hours after quitting. Symptoms can last for around two to seven days. Gradually reducing caffeine intake over several days does not trigger these symptoms.
2. Does coffee cause osteoporosis?
Caffeine
However, further studies and research are necessary.
3. Does caffeine sober you up?
People who have drunk too much alcohol may turn to coffee or an energy drink to sober them up.
However, caffeine
In fact, it could be more dangerous because, without the drowsiness, a person is more likely to believe they are sober, which could lead to hazardous activities such as driving home or consuming more alcohol.
There is some controversy around energy drinks. Student campuses often ban them because of reports of health problems and even fatalities.
The amount of caffeine in an energy drink depends on the brand and type.
While a 16-ounce Americano coffee can contain 225 mg of caffeine, the caffeine content of a 16-ounce energy drink, until recently, ranged from 160 mg to 357 mg.
Many energy drinks carry a health warning that children should not consume them, those with heart problems, or those who may have an intolerance to caffeine.
Energy drinks contain not only caffeine but also other plant-based stimulants, simple sugars or artificial sweeteners, and additives. These high concentrations of caffeine and sugar could have a negative impact on the body.
Mixing alcohol and energy drinks
When a person mixes alcohol with energy drinks, the caffeine can mask the depressant effects of alcohol. Alcohol also decreases the metabolism of caffeine, prolonging its effects.
Drinkers who consume alcohol mixed with energy drinks are more likely to binge drink than drinkers who do not report mixing alcohol with energy drinks.
A person is unlikely to die from consuming too much caffeine in the diet. Vomiting would most certainly occur before a person had a chance to consume a fatal overdose of caffeine from dietary sources.
However, pure caffeine is a powerful stimulant, and very small amounts can lead to an accidental overdose. A single teaspoon of pure caffeine can equal 100 cups of coffee, depending on the strength.
Over-the-counter caffeine tablets also carry a risk of overdose.
In addition to the usual adverse effects from too much caffeine, high doses can lead to:
- anxiety
- heart palpitations and rapid heartbeat
- sweating
- nausea and vomiting
- cardiac arrest
Whether consumed as food or medication, the blood and body tissues absorb caffeine within approximately 45 minutes.
While there, caffeine changes the way the brain and body work. Caffeine has a similar structure to adenosine, a chemical that is present in all human cells. In the brain, adenosine acts as a CNS depressant.
Adenosine promotes sleep and suppresses arousal by slowing down nerve activity. Adenosine binding also causes blood vessels in the brain to dilate, to increase oxygen intake during sleep. When awake, the levels of adenosine in the brain rise by approximately one hour, making the brain and body less alert.
To a nerve cell, caffeine looks like adenosine, and caffeine binds to the adenosine receptors.
However, unlike adenosine, it does not decrease the cell’s activity. As caffeine utilizes all the receptors adenosine binds to, the cells can no longer sense adenosine. As a result, instead of slowing down because of the adenosine level, cellular activity speeds up.
Caffeine blocks adenosine’s ability to open up the brain’s blood vessels, causing them to constrict. This is why caffeine is used in pain relief medication for headaches. If the headache is vascular, relief comes as the caffeine narrows the blood vessels.
The blocking of adenosine causes excitatory neurotransmitters to increase in the brain. The pituitary gland notices this increased activity and releases hormones that tell the adrenal glands to produce epinephrine.
Negative effects of caffeine include:
- jitteriness
- increase in heart rate
- insomnia
- issues with digestion
Quitting caffeine can have positive effects of the body, including better quality sleep, lower anxiety, and a lower risk of heart issues.
The FDA recommends an intake of no more than 400 mg a day.
Moderate amounts of caffeine appear not to be harmful, and a moderate intake of caffeine may bring health benefits. The FDA recommends an intake of no more than 400 mg a day.
However, the impact will vary depending on the amount consumed, the individual’s size, sex, and sensitivity to the effects, as well as any medications or supplements they may be taking.
Pure caffeine can be dangerous, even life threatening, and should be avoided.
Additionally, the current trend of adding caffeine to foods such as gum and ice cream, which are commonly targeted at children, remains a matter of concern, and investigations are ongoing.
Anyone wishing to give up caffeine should gradually reduce their intake over several days rather than stopping abruptly, to avoid uncomfortable symptoms.