Does caffeine really benefit health?

Several important body systems are simultaneously affected by caffeine.

While caffeine has mainly beneficial effects, it can be poisonous under certain circumstances. A healthy adult may benefit from consuming up to 400 mg of caffeine per day, but pregnant women should limit their intake to no more than 200 mg per day.

Define caffeine

Plants that produce caffeine benefit from this interesting biological compound in numerous ways. Caffeine, which can be found in tea leaves, cocoa beans, and guarana seeds, serves as a biological weapon by warding off leaf-eating insects and green competitors. When these seeds germinate, caffeine enters the soil and renders it unsuitable for other plants to grow. Pollinating bees that visit coffee flowers are rewarded by caffeine, which encourages them to return repeatedly, increasing the plant’s chances of reproduction.

Humans can also be affected by caffeine in a manner similar to bees and insects, and its impact is determined by the dosage. The similarity of caffeine to adenosine, a biologically active substance that plays a significant role in the human body, is attributed to its effect.

Molecules of adenosine triphosphoric acid (ATP), composed of adenosine and three phosphoric acid residues, store all energy in our body. When the tails of an ATP molecule are detached, energy is transferred to proteins, leaving only adenosine behind.

ATP requires time to recharge. As adenosine levels build up in the body, they bind to adenosine receptors, which are present on neurons in the brain. This is how the body recognizes the need for rest.

Caffeine is structurally similar to adenosine but does not transmit any signals. Rather, caffeine simply occupies receptors without activating them. As a result, adenosine continues to accumulate in the body, but the brain does not detect it, and we do not feel tired.

Within an hour of consuming coffee, caffeine is absorbed in the intestines, enters the bloodstream, and crosses the blood-brain barrier, reaching the brain. After about two hours, the concentration of caffeine in the brain peaks, and it begins to occupy adenosine receptors. The greater the amount of coffee consumed, the more adenosine receptors caffeine will occupy, leading to more pronounced stimulating effects.

The duration of caffeine’s action on the body is influenced by a person’s genetic makeup and the amount of coffee they consume. Enzymes encoded by the CYP1A gene are responsible for degrading caffeine. Different individuals inherit various forms of this gene from their parents, resulting in varying enzyme activity rates. Some forms of the gene encode enzymes that degrade caffeine rapidly, while others encode slower-acting enzymes. As a result, some individuals feel energized by coffee throughout the day, while others experience little to no effect. Once enzymes free most of the caffeine receptors by about 10 pm, adenosine accumulated in the body binds to its receptors, causing drowsiness.

Caffeine: how it affects the body

Caffeine’s effects on the brain

A dosage of 30 to 300 mg of caffeine can increase alertness and reaction time, even in well-rested individuals. Caffeine also helps mitigate the negative effects of sleep deprivation, improving decision-making and information retention. This is especially crucial when a sleep-deprived person is operating a vehicle.

However, caffeine does not appear to enhance creativity. An experiment in 2020 involving 80 participants demonstrated this. Half of the volunteers received a placebo, while the other half received a 200 mg caffeine pill. They were then asked to solve a series of problems, with some requiring a correct answer and others requiring a non-standard solution. Overall, caffeine users performed better on practical problems but showed no improvement on creative problems compared to those who received placebos.

The brain’s response to regular caffeine consumption has been scarcely studied, but some benefits of caffeine have been observed. Specifically, 13 studies have reported a 30% lower risk of developing Parkinson’s disease in individuals who consume three cups of coffee daily, compared to those who abstain from coffee.

Parkinson’s disease is a severe condition caused by the gradual accumulation of harmful proteins in neurons, with an incidence rate of 120 cases per 100,000 individuals.

However, it is premature to conclude that coffee consumption provides protection against Parkinson’s disease. The observed effect was only found in studies where researchers observed individuals who drank or did not drink coffee or tea. Further investigation is required to confirm whether caffeine confers protection against other factors.

Similarly to Parkinson’s disease, the impact of caffeine consumption on Alzheimer’s disease is unclear. Although four observational studies suggest that coffee and tea drinkers have a lower risk of developing the disease compared to non-drinkers, further research is necessary to establish a definitive link.

Despite this, the exact influence of caffeine on mental illness remains uncertain. Studies indicate that there is a minimal correlation between caffeine and mental illness.

A ten-year study conducted on 50,000 American women revealed that those who consumed 2-4 cups of coffee per day were less susceptible to depression than those who only drank one cup.

How caffeine affects the heart and the blood vessels

Adenosine receptors are present in both the heart and blood vessels, and when adenosine binds to these receptors, it slows down the heartbeat. However, caffeine blocks adenosine from affecting the heart rate, leading researchers to suspect that even small amounts of caffeine can cause arrhythmias by disrupting the heart rate.

The impact of caffeine on the heart has been studied since 1988, yet it has not been proven that safe doses of caffeine can cause arrhythmias in healthy adults.

For individuals who rarely or never consume caffeinated beverages, a dosage of 250 mg of caffeine can increase blood pressure by 10 mmHg. This rise in pressure is not harmful to health, as it usually returns to normal levels shortly thereafter.

As individuals continue to consume coffee or tea regularly, their body becomes accustomed to the caffeine intake, and their blood pressure stabilizes. Therefore, individuals who consume caffeine within recommended limits are no more likely to develop hypertension than those who abstain from caffeine altogether.

People with pre-existing heart disease are at higher risk for developing arrhythmias.

For individuals with high blood pressure, a dose of 250 mg of caffeine can increase blood pressure by more than 1.5 times. Additionally, the older the person, the more significant the effect. Due to this, individuals with hypertension are advised to either reduce or entirely eliminate their caffeine intake. The decision to do so should be made in consultation with a medical professional.

The effects of caffeine on the endocrine system

Multiple studies have shown that women who consume more than two cups of coffee per day over several years are less likely to develop type 2 diabetes than those who consume less than two cups.

In a ten-year study involving 88,000 American women who recorded their caffeine intake and underwent testing, researchers observed this effect. However, the reason for this phenomenon remains unknown. One theory suggests that there may be a connection between caffeine consumption and the increase in adiponectin levels in the bloodstream. Adiponectin is a hormone that improves cell sensitivity to insulin, thereby preventing the development of type 2 diabetes.

Despite the observed correlation between caffeine consumption and a lower risk of developing type 2 diabetes in some studies, it is important to note that this connection has not been definitively proven. As a result, the authors recommend against relying on coffee or tea as a means of preventing type 2 diabetes, instead advocating for a balanced diet and an active lifestyle, which have been demonstrated to be effective in combating the disease.

Although adenosine receptors are present in other organs, our findings suggest that caffeine does not have any impact on them.

At recommended doses, caffeine is not a diuretic, does not increase the risk of fractures, and is not associated with any form of cancer.

The effects of caffeine on lifespane

In 2014-2015, research demonstrated that individuals who consume between three and five cups of coffee per day have a reduced risk of mortality related to chronic diseases such as type 2 diabetes, certain cancers, and suicide.

A 2018 study analyzing data from over 500,000 individuals confirmed that the health benefits associated with coffee consumption apply to individuals regardless of whether they have the CYP1A gene.

More recently, Norwegian researchers examined data from 117,228 women and found that coffee consumption does in fact decrease the risk of premature death resulting from chronic illnesses. However, the reasons for this phenomenon are still unknown.

When coffee can harm you

Caffeine has a systemic effect on the body since it interacts with adenosine receptors present in almost all organs, including the cardiovascular system, lungs, bladder, and brain. However, consuming too much caffeine can have a negative impact on the body, but healthy adults without chronic conditions or pregnancy can consume up to 400 mg of caffeine daily without harm. This amount can be found in two to four 230 ml cups of coffee.

Even if an individual drinks more than four cups of coffee or tea, they won’t experience caffeine poisoning. Fatal poisoning cases usually result from taking around 10 grams of caffeine, which is often due to overdosing on medication or energy drinks. Consuming the same amount of caffeine from coffee would require drinking 20 liters of coffee per day.

Some healthy individuals over the age of 18 may be hypersensitive to caffeine, so scientists and doctors suggest limiting caffeine intake to 400 mg to ensure there are no issues and that the health benefits are entirely positive.

It is not recommended to consume adult caffeine dosages for individuals under 18, pregnant women, and those with cardiovascular disease. Being aware of this can assist you in avoiding unintentionally causing harm to yourself.

It is safest for children to avoid caffeine consumption until the age of six since they can be poisoned by an adult dosage of caffeine due to their lighter weight. Children between the ages of 6-12 with an average weight of 30 kg can only absorb up to 75 mg of caffeine, while teenagers between the ages of 13-17 with an average weight of 55 kg can only intake 137.5 mg of caffeine per day.

Regular caffeine dosages are also not recommended for pregnant women. The risk of miscarriage and low birth weight increases when a pregnant woman consumes caffeine beyond the recommended dose. The American College of Obstetricians and Gynecologists therefore advises pregnant women to limit their caffeine consumption to no more than 200 mg per day.

Does caffeine make you addicted?

A chemical compound that affects the mind is known as a psychoactive substance, and caffeine falls under this category. It is important to note, however, that not every psychoactive substance is considered a drug.

Drug use is associated with the brain releasing significant amounts of the neurotransmitter dopamine in the nucleus accumbens. This structure is responsible for motivation and the development of addictions.

In contrast, consuming caffeine at recommended dosages also triggers the release of dopamine, but this process occurs in a different part of the brain known as the prefrontal cortex. This area of the brain is responsible for attention and self-control and does not contribute to addiction development. As a result, consuming caffeine at recommended doses does not induce drug cravings or pose any problems for the coffee drinker or their loved ones.

Individuals who consistently exceed the recommended dosage of caffeine may develop caffeine-related disorders, making it challenging for them to reduce their caffeine consumption.

Those with this disorder may feel compelled to increase their caffeine intake as previous doses lose their effectiveness over time, and without it, they may experience discomfort. Additionally, this disorder increases the risk of addiction to more dangerous psychoactive substances, such as tobacco or alcohol.

Around half of those who attempt to quit caffeine suddenly experience withdrawal symptoms, such as headaches, nausea, drowsiness, lethargy, and muscle aches. Symptoms usually occur 12-24 hours after the last dose, peak after one to two days, and last approximately nine days. Gradually reducing caffeine intake over a period of two to three weeks, rather than stopping suddenly, can help avoid withdrawal symptoms.

Over time, caffeine sensitivity may recover. In approximately a year, individuals who previously experienced this disorder can enjoy coffee or tea occasionally again.

Calculating the optimal caffeine dose

If coffee is your preferred source of caffeine, then consuming no more than two cups of brewed coffee or four cups of instant coffee, with each cup not larger than 230 ml, will allow you to remain within the recommended 400 mg caffeine limit.

However, if you consume other caffeinated beverages like tea or energy drinks, or take caffeinated medications, it is crucial to take note of the caffeine concentration listed on their labels.

Alternatively, you can refer to a table provided by the authors of the international guide for doctors.

Caffeine content in food and beverages

Product	Portion in ml	Caffeine content in mg
Brewed Coffee	235	102-200, average 133
Instant Coffee	235	27-173, average 93
Decaffeinated Coffee	235	3-12, average 5
Espresso	30	30-90, average 40
Decaffeinated Espresso	30	4
Brewed Tea	235	40-120, average 53
Bottled Nestea Tea	355	26
Regular and Diet Coca-Cola	355	35-47
Red Bull Energy Drink	245	80
Monster Energy Drink	470	160
Hot Chocolate	235	3-13