Is caffeine harmful to health?
– Absolutely. Everyone talks about it.
– Unlikely. Otherwise, it would have been banned.
– Depending on… how much is consumed.
Questions about the harm of this popular stimulant have long since moved into the category of “chewed over,” eliciting ironic smiles from users towards those asking. The answers to these questions no longer surprise anyone, partly due to their frequent mutual contradictions.
Due to its great popularity, caffeine has been well studied by scientists, and research confirms a high degree of mythologization of public opinion about this substance.
This article is dedicated to those who consume caffeine, are accustomed to it, and are open to looking at the scientific facts regarding its impact on health.
1 Harm of caffeine to the heart
Caffeine and blood pressure
The most common opinion regarding the harm of caffeine to the heart is that caffeine is harmful to the heart and leads to chronic high blood pressure.
Research indicates that a sharp increase in blood pressure is characteristic of individuals for whom caffeine consumption is not a habit or after 1-4 days of abstaining from it 1.
In one study, when healthy non-coffee drinkers consumed a single dose of 250 mg of caffeine, their blood pressure increased on average by 14/10 mm Hg after one hour. It only normalized after 4 hours 10.
At peak caffeine levels in the blood 60 minutes after consumption, the effect of increased pressure due to vasoconstriction is stronger in those who typically do not consume caffeine than in habitual users, whose bodies are accustomed to the stimulant 14.
In individuals with chronically high blood pressure, the reaction to caffeine is more pronounced than in those without hypertension 11.
In an experiment involving hypertensive patients, a caffeine intake of 3 mg/kg provoked a sustained increase in diastolic pressure for 3 hours, while in healthy individuals, it also increased but normalized after 90 minutes 12.
One of the side effects of caffeine consumption is a short-term increase in blood pressure. This is especially characteristic of non-consumers and hypertensives.
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Caffeine and Hypertension
“Regular moderate consumption of caffeine does not lead to an increased risk of developing hypertension“, conclude researchers from the University of Tennessee based on a study of young healthy individuals who drink 3-4 cups of coffee a day over a long period 13.
However, the impact of regular doses of caffeine on blood circulation in the body is a hot topic in scientific circles.
Chronic hypertension as a side effect of caffeine consumption is not a scientifically confirmed fact.
Caffeine and the Risk of Death from Cardiovascular Diseases
Clinical studies do NOT confirm that the consumption of caffeine in the form of caffeine-containing beverages increases the risk of death from cardiovascular diseases in individuals with hypertension 16, unlike smoking.
Moreover, scientists claim that caffeine intake is associated with a lower risk of death from ischemic heart disease, as well as the development of valve diseases 17.
The authors of one of the recent meta-analyses on the benefits and harms of caffeine (an analysis of all available scientific studies) conclude that those individuals who drink 4 cups of coffee daily have a substantially lower risk of heart attack (by 11%) compared to those who do not drink coffee at all; 1-3 cups reduce the risk by 4-10% 2.
Of course, the daily dosage matters. In our material on the harms of energy drinks, which also contain caffeine as one of the active ingredients, several examples of young people dying after consuming several cans of the drink are provided.
Scientific research indicates that regular caffeine intake not only does not increase the risk of death from cardiovascular diseases but may even reduce it. Of course, it all depends on the dosage.
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2 Harm of caffeine for the eyes
Caffeine can affect intraocular pressure.
This was demonstrated in an experiment involving patients with glaucoma (damage to the optic nerve), where those who consumed 200 mg of caffeine or more per day had significantly higher intraocular pressure than those who consumed less than 200 mg of caffeine per day 18.
Analysis of scientific studies shows that caffeine DOES NOT increase intraocular pressure in healthy individuals; this is only observed in patients with glaucoma or ocular hypertension 19.
Caffeine intake may lead to increased intraocular pressure in individuals suffering from glaucoma, but poses no harm to healthy individuals.
3 Caffeine poisoning or overdose
As with any beneficial substance, uncontrolled consumption of caffeine can cause serious harm to health.
Caffeine poisoning occurs with its dosage. A dose of 20-40 mg per kilogram of body weight is considered dangerous (1.8-3.6 g for a 100 kg person).
In cases of caffeine overdose, it is even possible to die. The lethal dose of caffeine is approximately 10 g.
Symptoms of caffeine overdose include:
- nervousness;
- unexplained anxiety;
- irritability;
- increased urination;
- sleep disturbances (insomnia);
- muscle twitching, etc.
Caffeine poisoning occurs with an overdose of 20-40 mg/kg, the lethal dose of caffeine is approximately 10 g
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4 Caffeine and “belching”
The relationship between coffee and so-called belching is known, if not to everyone, then to many coffee lovers and those around them.
One study showed that healthy individuals who regularly consume more than three cups of coffee a week experience a contraction of the esophagus and the expulsion of stomach contents into the esophagus after consuming one serving of coffee (or 3.5 mg of caffeine per kilogram of body weight), which causes the characteristic sound of “belching” and the unpleasant sensation of acidic mass in the throat 20.
5 Harm of caffeine during pregnancy
Various facts indicate that caffeine consumption during pregnancy can harm the unborn baby.
It is clear that there is no definitive evidence for this, and it is unlikely that such evidence will emerge, as conducting such scientific experiments contradicts ethical norms.
Scientists talk about the absence of a placental barrier for caffeine (between the mother’s body and the child) 7, as well as the blood-brain barrier in the fetus (between the child’s body and the brain) 8.
This means that if a pregnant woman consumes caffeine, it passes directly from her body into the child’s brain.
Even more importantly, caffeine is eliminated from the fetus’s body over several days, compared to a few hours in adults: the half-life of caffeine in adults is 2-5 hours, while in newborns or premature infants it is from 75 to 100 hours 9.
There is no definitive scientific evidence of caffeine’s harm to the fetus during pregnancy, but it seems reasonable to refrain from its consumption during this period or to reduce the dose, as caffeine penetrates the fetal brain and is eliminated from the body very slowly.
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6 Caffeine and Alcohol
Caffeine and alcohol have an interesting synergistic effect on the body.
This is manifested in the fact that a person with alcohol in their system inadequately assesses their condition, the degree of impairment of physical coordination and brain activity even when the amount of alcohol consumed is quite large 3.
Caffeine does NOT reduce the intoxicating effects, contrary to popular belief, but rather “masks” it 4.
If alcohol is consumed with caffeine-containing energy drinks, another synergistic effect is observed: the rate of alcohol absorption increases due to the carbon dioxide present in the energy drinks, which is used for carbonation 5.
The stimulating effect of caffeine further encourages alcohol consumption 3.
Interestingly, there is a clear social pattern: alcohol enthusiasts not only have an increased need for self-assertion, heightened sexual desire, and a tendency to use drugs, but they are also very often dependent on caffeine 6.
Caffeine and alcohol have synergistic effects: caffeine dulls the sensation of intoxication. Caffeinated energy drinks accelerate alcohol absorption.
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7 The Harm of Caffeine from Coffee and Fat-Burning Pills
A meta-analysis of 16 studies on the difference in the effects of caffeine from coffee and fat-burning pills shows that coffee (caffeine dosage 725 ml/day) and fat-burning pills (caffeine dosage 410 mg/day) have different effects on blood pressure: the increase in blood pressure is stronger in the case of pills.
Why?
Pure caffeine in pills raises blood pressure more than coffee
According to scientists, the possible reason for the greater harm of pills is that their intake is NOT accompanied by the effects of satisfaction, such as physical and mental relaxation; also, pills lack some substances that are present in coffee and have a positive effect on the cardiovascular system 15.
