- People with signs of cardiovascular disease, such as angina and heart palpitations, are more likely to drink less coffee, skip coffee entirely, or drink decaf, according to a survey.
- The researchers used a genetic technique to demonstrate that these signs, rather than the other way around, decide how much coffee people drink.
- The study contradicts empirical evidence that drinking moderate quantities of coffee is good for your heart.
Coffee has become one of the world’s most popular drinks due to its distinct flavour and aroma, as well as its ability to wake people up in the morning.
Coffee can also protect against cardiovascular disease, diabetes, Parkinson’s disease, and some cancers, according to observational studies.
Drinking this beverage is healthy for most people and is linked to lower mortality rates, according to prospective research, which follows people over time.
However, a recent study indicates that some of the claimed cardiovascular health benefits of coffee may have been exaggerated. Only white British people took part in the study.
Excessive coffee intake can cause unpleasant symptoms such as tachycardia (a fast resting heart rate) and palpitations due to the caffeine content.
Coffee consumption can cause a mild, transient rise in blood pressure.
As a result, it can come as a surprise that daily coffee drinkers have normal or lower blood pressure than non-coffee drinkers.
One theory is that coffee drinkers build a physiological immunity to caffeine’s impact.
However, according to a new report, people with a high genetic risk of cardiovascular disease limit their drinking unconsciously to prevent uncomfortable cardiovascular symptoms.
People with high blood pressure, angina, or arrhythmia drank less caffeinated coffee and were more likely to drink decaffeinated coffee, according to the report.
Importantly, there was clear evidence that their genetic susceptibility to cardiovascular disease contributed to a reduction in coffee intake.
This rules out the possibility that they were more susceptible to cardiovascular disease because they drank less coffee.
The study, which was published in The American Journal of Clinical Nutrition, was conducted by researchers at the University of South Australia in Adelaide.
Guided by genetics
Professor Elina Hyppönen, who led the study and directs the Australian Centre for Precision Health at the university, said, “Whether we drink a lot of coffee, a little coffee, or avoid caffeine altogether, this study shows that genetics is driving our decisions to protect our cardio health.”
“If your body is telling you not to drink that extra cup of coffee, there’s likely a reason why,” she adds. “Listen to your body — it’s more in tune with your health than you may think.”
This effect may lead to the false perception that coffee lowers blood pressure and protects the heart in observational studies.
In fact, people with high blood pressure can actually avoid drinking coffee because the caffeine causes them to experience unpleasant side effects.
The researchers used data from 390,435 white British participants aged 39 to 73 years old who are part of the UK Biobank medical and genetic database.
At the time of recruitment, participants reported that they drank coffee on a regular basis. Researchers often took their blood pressure and heart rate, as well as noting any signs of cardiovascular disease.
When opposed to those who did not have these signs, those with elevated blood pressure, angina, or arrhythmia drank less caffeinated coffee.
The researchers used a statistical technique called Mendelian randomization to see if daily coffee consumption caused the symptoms or if the symptoms caused a decrease in coffee consumption.
This method takes advantage of the chance inheritance of genetic variants that increase a person’s risk of a specific outcome later in life — in this case, the connection between blood pressure and heart rate and coffee consumption.
Since lifestyle and diet have no effect on a person’s genetic sequence, any correlations found by the researchers must be attributed to gene variations rather than other causes.
They discovered that having a specific genetic variant dictated how much coffee a person drank when they analysed the data.
Prof. Hyppönen explains, “What this suggests is that anyone who drinks a lot of coffee is definitely more genetically tolerant of caffeine than anyone who drinks very little.”
“A noncoffee drinker, or someone who drinks decaffeinated coffee, on the other hand, is more vulnerable to the negative effects of caffeine and to high blood pressure,” she continues.
Effects on the mind
Prof. Hyppönen was asked by Medical News Today if the psychological effects of excessive coffee consumption, such as anxiety and agitation, might also play a role.
“This is not something we looked at in our research, but any unpleasant sensation a person experiences as a result of coffee consumption is likely to reduce their desire to drink coffee,” Prof. Hyppönen said.
Dr. Edo Paz, a doctor at digital primary care platform K Health, spoke with MNT about the dangers of excessive coffee consumption.
Drinking too much coffee can result in headache, anxiety, tremors, and difficulty sleeping. With regards to the heart, in particular, excess coffee intake can result in palpitations and may trigger events in the heart, such as abnormal heart rhythms, in susceptible individuals.”
The problem of reverse causation
According to the results of the new study, observational studies that found a connection between coffee consumption and better health could have been victims of “reverse causation.”
In other words, rather than the other way around, heart disease caused people to drink less coffee.
Mendelian randomization tests, according to Prof. Hyppönen, have cast doubt on other ostensibly protective results.
Epidemiological studies, for example, have led people to believe that moderate alcohol intake protects against cardiovascular disease and that being overweight decreases mortality as compared to being moderately overweight.
“There seems to be little advantage of having [excess weight] versus [slim or moderate] weight, with the potential exception of smokers, according to [Mendelian randomization] studies,” she said.
Smoking suppresses appetite and therefore weight gain, but it also has a slew of negative health consequences.
“Similarly, [the] evidence indicates linear changes in blood pressure and stroke risk, with little advantage for light alcohol consumption,” she added.
While more research with a more diverse population is needed, this study suggests taking a thoughtful, personalised approach to encouraging high coffee consumption.