The health benefits and risks of caffeine

Caffeine is a stimulant and the most commonly used drug in the world. Every day, millions consume it 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, a high consumption of caffeine may not be healthful. In addition, the recent trend of adding caffeine to drinks and snacks that do not naturally contain it has raised new concerns.

This article will look at the potential health benefits and risks of caffeine, the questions of energy drinks, and the likelihood of a caffeine overdose occurring.

The Food and Drug Administration (FDA) consider caffeineTrusted Source to be both a drug and a food additive. They recommend a maximum intake of 400 mg a day.

In prescription and over-the-counter (OTC) medicines, caffeine is used to treat tiredness and drowsiness, and to improve the effect of some pain relievers.

It belongs to a group of medicines called central nervous system (CNS) stimulants.

Foods containing caffeine can help restore mental alertness.

Caffeine’s use as an alertness aid should only be occasional. It is not intended to replace sleep and should not regularly be used for this purpose.

In the United States (U.S.), more than 90 percentTrusted Source of adults use caffeine regularly, with an average consumption of more than 200 milligrams of caffeine per day. This is more caffeine than in two 6-ounce cups of coffee or five 12-ounce cans of soft drink.


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, jelly beans, waffles, water, syrup, marshmallows, sunflower seeds, and other snacks.

The FDA recommends that healthy adults limit their caffeine intake to a maximum of 400 milligrams (mg) a day, about 4 or 5 cups of coffee. This amount is not associated with negative effects.

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 are:

• One 8-ounce cup of coffee: 95 to 200 mg

• One 12-ounce can of cola: 35 to 45 mg

• One 8-ounce energy drink: 70 to 150 mg

• One 8-ounce cup of tea: 14 to 60 mg

Decaffeinated cola and soft drinks contain no caffeine, but decaffeinated coffee is not caffeine-free.

“Energy drinks” contain varying amounts of caffeine.

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 has questioned the safetyTrusted Source of this practice.


Caffeine may have some health benefits, but not all of these have been confirmed 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 that are marketed as thermogenics may contain caffeine and ephedra, or ephedrine.

Research has not confirmed long-term results.


A 75-mg serving of caffeine can increase attention and alertness, and a 160 to 600-mg dose may improve mental alertness, speed reasoning, and memory.

However, caffeine is not a substitute for sleep.

Sports performance

Caffeine can improve physical performance during endurance exercise.

The European Food Safety Agency (EFSA) recognize that caffeine can increase endurance performance, endurance capacity, and reduction in perceived exertion.

However, the effects on short-term, high-intensity exercise remain inconclusive.

Brain function

Caffeine affects adenosine receptors in the brain. Coffee also contains polyphenol antioxidants, and these, too, act on various pathways.

Studies have suggested that drinking coffee may help enhance some thinking skills and slow the mental decline that comes with age.

However, more research is needed to confirm this.

Alzheimer’s and Parkinson’s disease

Research has found that lifelong caffeine consumption may reduceTrusted Source the risk of developing Alzheimer’s disease.

Studies have also reported that people with a higher coffee consumption have a lower risk of Parkinson’s disease.


Research from Johns Hopkins University suggests that a dose of caffeine after a learning session may help boost long-term memory.

Liver and colon

It has been suggested that caffeine enemas may help prepareTrusted Source the colon for an endoscopy or colonoscopy by supporting the excretion of bile through the colon wall.

Proponents claim that a caffeine enema increases the levels of glutathione, an antioxidant, and so it supports the natural processes of detoxification in the liver.

Coffee consumption may help decrease the risk of cirrhosis and slow the rate of disease progression in hepatitis C infection. Observational studies have found that coffee may have protective benefits for people with hepatocellular cancer.

Eyelid spasm

There is some evidence that caffeine may help protect people from an eye disorder known as blepharospasm.

This condition, caused by abnormal brain function, makes people blink incessantly and can leave them functionally blind.


Researchers have found that caffeine may help protectTrusted Source the lens of the eye against damage that could lead to the formation of cataracts.

Skin cancer

Some scientists have suggested that caffeine may guard against certain skin cancers.

One team found that caffeine applied directly to the skin of mice helped prevent damaging ultraviolet (UV) light from causing skin cancer.

Others have linked the consumption of three cups of caffeinated coffee a day with a 21 percent lower risk of developing basal cell carcinoma in women, and a 10 percent lower risk in men, compared with drinking less than one cup per month.

Kidney stones

A study of 217,883 participants analyzed the association between caffeine intake and the risk of developing kidney stones.

Those who consumed more caffeine had a lower riskTrusted Source of developing kidney stones.

Mouth, throat, and other cancers

In a study of 968,432 men and women, participants who drank than 4 cups of coffee a day had a 49-percent lower risk of death from oral cancer, compared with those who drank no coffee at all or only an occasional cup.

Other possible cancer-related benefits include:

• a lower risk of endometrial cancer

• a reduced risk of prostate cancer

• protection against head and neck cancer

• protection against the recurrence of breast cancer


Data for 34,670 women in Sweden without a history of cardiovascular disease indicated that women who drank more than one cup of coffee per day had a 22 to 25-percent lower riskTrusted Source of stroke compared with women who drank less.

Low or no coffee drinking appeared to be linked to an increased risk of stroke.

Type 2 diabetes

One longitudinal study found that participants who increased their coffee intake by more than one cup a day over a 4-year period had a 1 percent lower riskTrusted Source of developing type 2 diabetes compared with people who did not change their intake.

People who lowered their daily consumption by more than one cup of coffee showed a 17 percent higher risk for type 2 diabetes.

A study published in Diabetes Care in 2004 linked a high coffee consumption over a period of 4 weeks with increased fasting insulin concentrations.

However, the reasons for the link were unclear. It may be due to lowered insulin sensitivity, meaning the body does not use the insulin produced efficiently.

The team called for more investigation before asserting that high coffee consumption lowers risk for type 2 diabetes.


Much of the published research about caffeine suggests that it is beneficial, in moderation.

However, some studies highlight the potentially harmful effects of caffeine.


A high caffeine intake may worsen symptoms of anxiety and depression.

Research published in 2016 found that, in 234 middle school students in Korea, a higher caffeine intake was linked toTrusted Source higher weight, lower academic achievement, and a higher risk of severe depression.

However, whether the 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.

TThere is some evidence that caffeine may impair insulin action, leading to a small but detectable rise in blood sugar levels, particularly after meals.


Studies have suggested that more than 300 mg a day of caffeine, or the amount equal to around three cups of coffee, could lead to:

• loss of pregnancy

• delayed fetal growth

• abnormal fetal heart rhythm

According to the National Institutes of Health (NIH), the weeks before pregnancy also count. Research shows that if both parents consume more than two caffeinated drinks a day in the weeks before they conceive, a loss of pregnancy may be more likelyTrusted Source.

Women should limit their caffeine intake to 200 mg or less during pregnancy.


Some research suggests that caffeine may reduce muscle activity in the fallopian tubes, which carry eggs from the ovaries to the womb.

This could mean, say the study authors, that caffeine reduces a woman’s chances of becoming pregnant by about 27 percent.


Caffeine passes into breast milk in small amounts, and it may build up in the nursing infant.

Infants whose mothers drink large amounts of caffeinated beverages may be jittery and have trouble sleeping.


An additional intake of caffeine may trigger a gout attack in people with the condition.

Drinking six or more caffeinated beverages in 24 hours has been associated with an almost four-fold increase in the risk of recurrent gout attacks.


A study that looked at 1,356 women found that those with an intake of 329 mg of caffeine a day, equivalent to about three cups of coffee or more, had a 70-percent higher chance of bladder problems.


Consuming caffeine 3 and even 6 hours before bedtime can significantly disrupt sleep. Up to 6 hours before bedtime, caffeine can reduceTrusted Source objectively measured total sleep time by more than 1 hour.


A population-based study found that dietary and medicinal caffeine consumption may be a modest risk factorTrusted Source for triggering chronic daily headache, regardless of headache type.


A study published in the journal Menopause found that women who consumed caffeine during menopause were more likelyTrusted Source to have hot flashes and night sweats.

Other adverse effects

Caffeine’s main effect on the body is an increased temporary sense of wakefulness and alertness, but it can also cause uncomfortable symptoms.

Consuming over 400 mg of caffeine a day can lead to:

• jitters and shakes

• disrupted sleep

• fast or uneven heartbeat

• high blood pressure

• headaches

• nervousness or anxiety

• dizziness

• dependency

• dehydration

• irritability

CCaffeine increases the release of acid in the stomach, sometimes leading to an upset stomach or heartburn.

Caffeine can interfere with the sleep cycle. Sleep loss is cumulative, and even small nightly decreases can add up and disturb daytime alertness and performance.

Drug interactions

Some medicines may interact with caffeine.

These includeTrusted Source some:

• Antibiotics

• Bronchodilators

• Antipsychotics, such as clozapine

• Some antidepressants

• Carbamazepine, as caffeine could increase the risk of seizures

A number of herbs and supplements can interact with caffeine to varying degrees:

• calcium

• echinacea

• ephedra

• kudzu

• melatonin

• magnesium

• red clover

References … ( What does caffeine do to your body? ). Written by Hannah Nichols on October 16, 2017

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