BP level, heart rate may affect coffee consumption
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Coffee consumption may be “naturally” regulated based on an individual’s BP level and heart rate, researchers wrote in The American Journal of Clinical Nutrition.
The findings could partially explain previous data that suggest coffee consumption, even in high amounts, may be beneficial, according to Elina Hyppönen, PhD, MSc, MPH, director of the Australian Centre for Precision Health at the University of South Australia Cancer Research Institute, and Ang Zhou, PhD, a research associate in the nutritional and genetic epidemiology group at the Australian Centre for Precision Health.
“We knew from past research that when people feel unwell, they tend to drink less coffee,” Hyppönen told Healio Primary Care. “This type of phenomenon where disease drives behavior — reverse causality — can lead to misleading health associations, and indeed, create a false impression for health benefits, if the group of people who do not drink coffee also includes more people who are unwell.”
The researchers analyzed data from up to 390,435 European ancestry participants aged between 39 and 73 years in the United Kingdom’s Biobank. Participants self-reported their coffee consumption and had their systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate measured at Biobank enrollment, while their baseline cardiovascular symptoms were obtained via hospital diagnoses, primary care records and self-reports.
According to Hyppönen and Zhou, participants who reported heart arrhythmia-related symptoms were 85% more likely to drink decaffeinated coffee and 53% more likely to not drink any coffee than to drink caffeinated coffee. Participants who indicated at baseline they were in “poor health” and experienced a “history of long-standing illness” were also more likely to drink decaffeinated coffee or to not drink any coffee than to drink caffeinated coffee.
In addition, higher SBP and DBP were linked to lower caffeinated coffee consumption at baseline, deeming the genetic evidence “consistent” to support a causal explanation, according to the researchers. Genetic analyses also showed that higher resting heart rate was linked to greater odds of being a decaffeinated coffee drinker (OR = 1.71; 95% CI, 1.31-2.21 for each 10 beats a minute).
“We saw that people who have higher BP tend to drink less coffee, and conversely that people with low BP tend to drink more,” Hyppönen said.
The results suggest that reverse causality may account for “some of the controversies in observational studies of coffee consumption,” she added.
“Perhaps even more interestingly, our results also suggest people subconsciously self-regulate safe levels of coffee based on how high their BP is, and this is likely a result of a protective genetic a mechanism,” Hyppönen said.
This means that those who drink more caffeinated coffee may be “more genetically tolerant of caffeine,” whereas noncoffee drinkers or those who drink decaffeinated coffee, could be “more likely prone to the adverse effects of caffeine, and more susceptible to high BP,” she said.
“Whether we drink a lot of coffee, a little, or avoid caffeine altogether, this study shows that genetics are guiding our decisions to protect our cardio health,” Hyppönen said. “If your body is telling you not to drink that extra cup of coffee, there’s likely a reason why. Listen to your body, it’s more in tune with your health than you may think.”
Perspective
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Zhaoping Li, MD, PhD
Our genetics determine our food preferences and metabolic response to food. However, the authors of this study did not use genetics. They also did not follow someone from the time they were born to the time they have a first heart attack, or what not. Therefore, from the point of view of this study having a take-home message for physicians, this study has none.
Research into coffee has been extensive over the past 20 years. Studies first showed that coffee drinkers are more likely to have the cardiovascular events and disease. But then there was an analysis that showed coffee drinkers are more likely to be smokers that may have impacted the study conclusion. More recent studies showed if you are not a smoker, the link between drinking coffee and heart disease becomes practically nonexistent. Other studies have shown that if you drink about three cups of coffee, you are protected from heart disease. You can see the potential flaws of analyzing existing data, since using existing data often depends on how you approach it.
That’s not to say that food research is not important. There are some estimates that indicate $20 billion will be spent on research during the next few years to figure out how genetics, environment and humans interactions impact what food does to our bodies.
References:
NIH. Nutrition for Precision Health. https://commonfund.nih.gov/nutritionforprecisionhealth. Accessed April 7, 2021.
O'Keefe JH, et al. J Am Coll Cardiol. 2013;doi:10.1016/j.jacc.2013.06.035.
Rebello SA, van Dam RM. Curr Cardiol Rep. 2013;doi:10.1007/s11886-013-0403-1.
Professor of medicine, Lynda and Steward Resnick Endowed Chair,
Director, Center for Human Nutrition,
Division chief, clinical nutrition, David Geffen School of Medicine at UCLA
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