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Coffee may harm heart health in people with hypertension

I write a lot about the health effects of coffee, and a new study provides evidence that it may not be so good for those with underlying heart issues like hypertension. I know that it may seem like medical science is bouncing back and forth with regard to the health benefits of coffee, but that’s how science works — it’s not dogmatic, it relies on new evidence.

There is some recent evidence that concluded that coffee may actually be linked to good heart health. Now, there is new evidence that it might not be good for the heart. What gives? Well, the first study showed health benefits for a general population of coffee drinkers. This new study examines coffee’s effects on individuals with underlying hypertension. Both studies give valid information, and they do not conflict with one another.

So, as I usually do, let’s take a look at this new research and I will point out some of the key findings of the research.

cappuccino in cup on table
Photo by Blank Space on

Coffee and heart health paper

In a paper published on 21 December 2022 in the respected Journal of the American Heart Association, Hiroyasu Iso, MD, Ph.D., MPH, and other researchers at the Institute for Global Health Policy Research, Bureau of International Health Cooperation, National Center for Global Health and Medicine in Tokyo, Japan followed 18,609 participants (6,574 males and 12,035 women) aged 40-79 years at baseline. The participants completed a lifestyle, diet, and medical history questionnaire. They also had baseline and follow-up medical examinations up until 2009.

Below are the findings of the researchers:

  • People with severe (grade 2-3) hypertension and who drank two or more cups of caffeinated coffee each day exhibited a 2X risk of dying from a heart attack, stroke, or any type of cardiovascular disease.
  • Individuals with no or grade 1 hypertension and who drank two or more cups of coffee showed no change in risk of cardiovascular mortality.
  • Drinking one cup of coffee a day or any amount of green tea was not associated with the risk of death across any blood pressure categories, and drinking green tea was not associated with an increased risk of death related to cardiovascular disease at any blood pressure level.

There were numerous confounders in evaluating the data in this study. The researchers found that frequent consumers of coffee were more likely to be younger, smokers, alcohol drinkers, to eat fewer vegetables, and to have higher total cholesterol levels. Many of those factors could be correlated to poor cardiovascular health (especially smoking).

person holding starbucks coffee tumbler
Photo by Bruno Cervera on


This study does not conflict with another recent study that seems to indicate that coffee had a positive benefit on cardiovascular health. Unfortunately, both studies have the same underlying issues — they rely upon the memory and accuracy of participants to determine how much coffee is being consumed. More than that, both studies seem to focus on caffeine, even though coffee has over 100 biologically active compounds in it. We don’t know if these compounds themselves have a positive or negative effect on cardiovascular health.

On the other hand, this study clearly showed that caffeinated coffee, especially two or more cups a day, could be deleterious to individuals with underlying heart issues, specifically severe hypertension. It is plausible that the caffeine in coffee can make severe hypertension even worse.

I’m going to give this article 3 out of 5 stars because it’s another coffee study that can almost convince me that it’s providing good data, but it’s not quite there because of the overreliance on the accuracy of reporting by participants.

However, I found the data that large amounts of coffee might have a negative effect on individuals with severe hypertension to be quite intriguing. Maybe healthcare professionals should warn those with that level of hypertension to refrain from coffee, though the evidence is not quite at the level of science-based medicine.


Michael Simpson
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