Starting the day off with a cup of coffee is the norm for many people who are getting ready for a long day of work ahead. Others may reach for coffee or even energy drinks as a mood booster in the middle of the day for that extra kick of energy. The source of this boost comes from the body’s response to the intake of caffeine present in these beverages.

Caffeine is a staple in many people’s daily diets and is often used to help aid their daily activities. It can be found in many forms readily available, so it is important to recognize these sources for safe consumption. In addition, there are possible helpful and harmful effects that caffeine may present to the body that all should be aware of.

What is Caffeine?

Caffeine is a mild stimulant classified as a drug, and it can be found naturally in over 60 plants. For human consumption, it is usually extracted from coffee and cacao beans. Nowadays, it is incorporated in several types of common beverages and food items. 

Billi UK, “How Much Caffeine is in Your Favourite Drinks?” Retrieved from https://www.billi-uk.com/caffeine-content-favourite-drinks/, accessed May 2021.

Consuming Caffeine Safely

The recommended amount for safe consumption of caffeine is 400 mg per day for adults. This value may change depending on factors such as age and health condition. 

According to the American Academy of Child & Adolescent Psychiatry (AACAP), there is no specific restriction on children’s caffeine intake. However, it is recommended that children 12 and older should be limited to 100 mg a day, and any child under 12 is not recommended to consume caffeine. 

Another group that should monitor their caffeine intake more carefully is pregnant women, whose recommended intake is 200 mg daily. This is due to caffeine’s ability to increase blood pressure, heart rate, and frequency of urination. Caffeine also can travel through the placenta and may affect the developing fetus more than the mother, by affecting the baby’s sleep and movement patterns. From studies done on animals, excessive caffeine intake may result in problems such as premature labor, reduced fertility, and birth defects. Even though these effects have not been studied on humans, pregnant women should still be cautious of these possibilities.

Effects on the Body

Caffeine can usually be absorbed within 45 minutes after consumption. Then, it can remain in the bloodstream for up to 9.5 hours. Upon absorption, the body can start to feel the effects including: 

• Restlessness or insomnia

• Anxiety and irritability

• Increased alertness and activeness

• Faster breathing and heart rate

• Dehydration 

• Headache

Under the recommended dose, the effects are not severe and usually dissipate after a few hours. It usually requires up to a dose of 10,000 mg for it to become toxic. However, regular consumption can cause the body to become dependent on this drug. 

The most studied aspects about caffeine target its effects on the cardiovascular and central nervous system. Caffeine has proarrhythmic effects at higher doses. Arrhythmia is a condition where the heart beats with an abnormal rhythm. There is no study to prove that caffeine is linked to heart diseases, but individuals with pre-existing heart conditions should limit their intake. 

Depending on the dosage, caffeine will have varying effects on brain health. In one study, it has been linked to increased cognitive performance up to 10 hours, but the overall benefits of caffeine on this enhancement are still under debate. It also can reduce an individual’s susceptibility to neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. This is the result of caffeine acting as a neuroprotective drug, protecting neurons from damage and preserving their functions. 

Caffeine Tolerance and Withdrawal

One significant mechanism of caffeine is its ability to act against adenosine receptors. The original purpose of these receptors is to manage cyclic adenosine monophosphate (cAMP) concentrations in the cell. When receptors are inhibited, it results in the release of norepinephrine, dopamine, and serotonin in the brain. Norepinephrine can increase heart rate, blood pressure, and blood sugar levels. Dopamine is a neurotransmitter that gives the body a sense of reward and satisfaction. Similar to dopamine, serotonin also affects mood, and it can help with daily activities like sleeping, eating, and digestion. 

At first glance, it seems there are many good qualities of caffeine, but the body can become overly dependent and lead to addiction. This will affect the body’s natural ability to produce norepinephrine, dopamine, serotonin, and other hormones without the aid of caffeine. With constant use, the stimulant effects of the drug will start to decrease over time, increasing tolerance. At a certain point, it will become hard to cut caffeine out of the diet, and like any other drug, individuals may face withdrawal symptoms if they attempt to do so. These can begin 12-24 hours after stopping consumption and include:

• Headaches

• Irritability

• Agitation

• Depression

• Fatigue 

By monitoring levels of consumption, withdrawal symptoms can be avoided, and a slow reduction in caffeine intake over time can prevent individuals from experiencing these symptoms. There have not been any proven effects that caffeine is severely damaging to the body, and most withdrawal symptoms will disappear after a few days.  

In terms of caffeine, there is not a correct answer to whether caffeine should be incorporated into a person’s diet, but being aware of its effects can help individuals to decide the safest caffeine intake level for themselves while considering their health conditions.