Coffee Consumption and Cardiovascular Health Body Regulation

"People drink coffee for all sorts of reasons -- as a pick-me-up when they're feeling tired, because it tastes good or simply because it's part of their daily routine."

"But what we don't recognize is that people subconsciously self-regulate safe levels of caffeine based on how high their blood pressure is, and this is likely a result of a protective genetic mechanism."

"What this means is that someone who drinks a lot of coffee is likely more genetically tolerant of caffeine compared to someone who drinks very little."

"Conversely, a non-coffee drinker, or someone who drinks decaffeinated coffee is more likely prone to the adverse effects of caffeine and more susceptible to high blood pressure."

Elina Hypponen, director, Australian Centre for Precision Health, University of South Australia

 

Recent research concludes variously that coffee as a stimulant is useful for decreasing obsessive compulsive behaviour of germaphobes all the way up to increasing the rate at which the body burns fat when consumed pre-workout. It can hardly be surprising that one of the most popular reached-for  beverages globally has intrigued researchers to study its properties and effects on people, and there are many effects of various kinds on many different people.

"Listen to your body, it's more in tune with your health than you may think", advises Dr.Hypponen, lead researcher of a recent study published in the Academic Journal of Clinical Nutrition. The study of almost 400,000 people revealed causal genetic evidence pointing to  n individual's cardiovascular health playing a role in that person's thirst for coffee, known for its caffeine-concentrated effects to start off the day.

Researchers involved in the study found that people with high blood pressure, angina and arrhythmia tend to drink less coffee, or to avoid it altogether. This is not a deliberate thought-out decision, but one that appears sub-conscious as though the body makes a decision in its best interests. The coffee-consumption habits of 390,435 individuals from the UK Biobank -- a large-scale health database containing in-depth genetic and medical data of a half million people -- compared this to baseline levels of systolic and diastolic blood pressure and heart rate.

The Mendelian randomization method used by the researchers established causation; it is an epidemiological technique using genetic variants in observational data to determine the effect of a modifiable exposure like coffee consumption. Some six million Canadians -- representing 19 percent of the population - suffer from high blood pressure with just 17 percent of people nationwide seemingly aware of their condition. 

High blood pressure represents the leading risk for death in the country. Research also bears out that at some time in their lives an estimated 90 percent of the Canadian population will develop high blood pressure or hypertension, typical of most populations in North America. Of those being treated for the condition, only two-thirds are known to exercise adequate control. The published study indicates that coffee assumes a relatively reliable role in the indication of cardiovascular health.

Methods: We used information from up to 390,435 European ancestry participants in the UK Biobank, aged 39-73 y. Habitual coffee consumption was self-reported, and systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate were measured at baseline. Cardiovascular symptoms at baseline were based on hospital diagnoses, primary care records, and/or self-report. Mendelian randomization (MR) was used to examine genetic evidence for a causal association between SBP, DBP, and heart rate with habitual coffee consumption.

Results: Participants with essential hypertension, angina, or heart arrhythmia were all more likely to drink less caffeinated coffee and to be non-habitual or decaffeinated coffee drinkers compared with those who did not report related symptoms (P ≤ 3.5 × 10-8 for all comparisons). Higher SBP and DBP were associated with lower caffeinated coffee consumption at baseline, with consistent genetic evidence to support a causal explanation across all methods [MR-Egger regression (MREggr) β: -0.21 cups/d (95% CI: -0.34, -0.07) per 10 mm Hg higher SBP and -0.33 (-0.61, -0.07) per 10 mm Hg higher DBP)]. In genetic analyses, higher resting heart rate was associated with a greater odds of being a decaffeinated coffee drinker (MREggr OR: 1.71; 95% CI: 1.31, 2.21) per 10 beats/min).

Conclusions: We provide causal genetic evidence for cardiovascular system-driven influences on habitual coffee intakes, suggesting that people tend to naturally regulate their coffee consumption based on blood pressure levels and heart rate. These findings suggest that observational studies of habitual coffee intakes are prone to influences by reverse causation, and caution is required when inferred health benefits result from comparisons with coffee abstainers or decaffeinated coffee drinkers.