Caffeine: Understanding the effects and risks

Caffeine: Understanding the effects and risks

Caffeine is a naturally occurring psychoactive agent in coffee. In several sodas and energy drinks, manufacturers also use it. Although it is a socially acceptable substance, reports on its safety and long-term effects are contradictory.

A study of university students in 2019 found that there is an average intake of around 173 milligrams per day (mg/day) for people who drink caffeine.

This is moderate caffeine intake. Moderate consumption can encourage a variety of health advantages, including a lower risk of some cancers, brain diseases, and liver disorders, according to several reports.

The consumption of caffeine, however, carries many risks. Drinking too much can lead to harmful effects as well.

We examine the possible health benefits and adverse side effects of the intake of caffeine in this article.

Natural stimulant

A lady drinking caffeine
Caffeine can help minimize fatigue.

In coffee, the main psychoactive component is caffeine. This is a compound that comes naturally from over 60 different sources of plants, including coffee beans, tea leaves, seeds of cacao, and seeds of cola nut.

By stimulating the central nervous system (CNS), caffeine serves as a stimulant. It can counteract fatigue and enhance attention and concentration.

People typically consume caffeine outside of coffee through tea, soft drinks, particularly energy drinks, and chocolate. In certain prescription and non-prescription medicines, such as cold, allergy, and pain medicine, it is also an ingredient.

Health benefits

Caffeine, as well as its calming effects, can offer several health benefits.

A 2019 evaluation of existing literature showed that there is a protective impact against liver cancer from consuming a moderate amount of caffeine.

A different study of 40 studies found in the same year that drinking 2-4 cups of coffee every day was associated with a decreased risk of death from all causes.

Several other studies have associated coffee intake with positive effects on the brain.

A research published in the World Journal of Biological Psychiatry in 2013 indicated that drinking 2-4 cups of coffee a day in adults can reduce the risk of suicide.

More recent studies in the journal Nature showed that long-term memory can be improved by consuming caffeine.

Other studies have also indicated that type 2 diabetes, Parkinson’s disease, cardiovascular disease, and stroke may be covered by caffeine intake.

A postdoctoral research fellow at the Johns Hopkins University School of Medicine, Steven E. Meredith, however, told Medical News Today that many people forget that caffeine is a psychoactive substance. This may be because of widespread consumption.

To stimulate the CNS, caffeine crosses the blood-brain barrier.

He said:

“Unlike most other psychoactive substances, caffeine use is socially acceptable, and the drug is widely used. In fact, caffeine is the most commonly used psychoactive substance in the world.

In addition, the vast majority of users of caffeine regularly use the substance without apparent harm. These variables are likely to lead to the perception that caffeine is a benign substance that can be used by anyone without having any harmful effects.

Learn about the health benefits of coffee here

Side effects

However, ingesting high doses of caffeine can lead to more adverse health effects.

Several undesirable side effects of consuming over 400 mg of caffeine per day were reported in a 2015 study, including:

  • anxiety
  • agitation
  • restlessness
  • sleeping problems
  • tremors
  • a fast heartbeat

When individuals undergo caffeine withdrawal, these symptoms may also occur.

Previous study, however, has related even moderate levels of caffeine to adverse health impacts.

The findings of a major prospective study in 2013 indicated that consuming 300 mg of caffeine a day during pregnancy could increase the risk of having a low-birth-weight baby.

A more recent meta-analysis of 17 studies that involved 233,617 participants recommended that drinking 3–4 cups of coffee every day may increase the risk of a heart attack in men but not in women.

In order to confirm whether long-term ingestion of caffeine is safe and whether it offers benefits or raises the risk of health problems, more research is required.


Meredith, however, told medicalnewtoday that the effects of caffeine will differ for each person. The mixed results of studies on the effect of caffeine on the body can be explained by this.

He advised, for example, that people with anxiety disorders are more prone to caffeine’s anxiety-increasing effects.

For different reasons, caffeine can also be metabolized at different rates among individuals. Cigarette smokers, for example, metabolize caffeine twice as rapidly as nonsmokers,” he added.

“However, caffeine metabolism is slower among infants, pregnant women, and individuals with liver disease. In addition, some medications slow caffeine metabolism, which may increase the risk of caffeine intoxication. But the effects of caffeine also vary simply because we’re all different.”

Rob M. Van Dam, Associate Associate Professor of the Harvard School of Public Health Department of Nutrition, told MNT that the effects of caffeine depend on individual genetic features and other lifestyle factors.

“Some people may have trouble sleeping or experience tremors or stress with relatively low intakes of caffeine, and if these occur, it is helpful to be aware of these symptoms and reduce the intake of caffeine.”

Addiction and withdrawal

Given the positive effects that caffeine can have as a stimulant, Meredith told MNT that for certain individuals, this may lead to caffeine addiction:

“Caffeine activates many of the same behavioral and neuropharmacological mechanisms that are activated by other reinforcers, including other drugs of abuse.

And caffeine is correlated with multiple beneficial subjective effects, such as increased well-being, sociability, and feelings of vitality and alertness, like many other reinforcers. A small percentage of the population develops caffeine use disorder for this cause and others.

Some individuals can become physically reliant on caffeine. In these people, the absence or reduction of coffee intake contributes to the withdrawal of caffeine.

This can cause a variety of symptoms, like:

  • a headache
  • tiredness
  • reduced energy and alertness
  • sleepiness
  • low mood
  • concentration problems
  • irritability

“Dependence can become so strong for some people that, despite knowledge of recurrent physical or psychological issues associated with continued use, they are unable to reduce consumption,” Meredith added.

Young people

Meredith indicated that doctors should address with their patients the use of caffeine in order to decide if they are consuming healthy stimulant levels.

He cautioned that this is critical for children and adolescents in particular.

As researchers do not completely understand its effects on the developing brain, the majority of pediatricians suggest that young people should stop drinking caffeine. This is explained by Meredith in the following terms:

Caffeine interferes with sleep, in particular, and sleep plays a vital role in learning. Some laboratory research indicates that caffeine interferes with adolescent rodent sleep and learning, which in turn hinders regular, observable neurological growth into adulthood.

“Some psychologists are also concerned that a pattern of young people’s use of caffeine or abuse can lead to subsequent problematic use of drugs and alcohol.”

The Food and Drug Administration (FDA) recommends that before adding caffeine into a young person’s diet, people speak to a pediatrician.

FDA Deputy Commissioner for Food and Veterinary Medicine Michael R. Taylor said:

“We are particularly concerned about children and adolescents, and the FDA and the food industry are responsible for protecting public health and respecting social norms that suggest that our children should not be marketing stimulants, such as caffeine.”

Many food and drink products now contain added caffeine to improve their calming effects, such as jellybeans, waffles, syrup, and chewing gum.


Mixed findings have been provided by research into the effects of caffeine.

Although moderate caffeine intake is unlikely to cause adverse effects in most individuals, stimulant reactions are based on highly specific factors, such as genetics and lifestyle choices.

People should be mindful that when they use caffeine, they are drinking a psychoactive substance.


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