“While smoking, age, and high blood pressure are among the most well-known heart disease risk factors, unidentified risk factors for heart disease remain,” said Dr. David Kao, a researcher at the University of Colorado School of Medicine.
“The risks and benefits of drinking coffee have been topics of ongoing scientific interest due to the popularity and frequency of consumption worldwide,” added Professor Linda Van Horn, a researcher at the Northwestern University Feinberg School of Medicine.
“Studies reporting associations with outcomes remain relatively limited due to inconsistencies in diet assessment and analytical methodologies, as well as inherent problems with self-reported dietary intake.”
The researchers used machine learning to examine data from the original cohort of the FHS study and referenced it against data from both CHS and ARIC studies to help confirm their findings.
Each study included at least 10 years of follow-up, and, collectively, the studies provided information on more than 21,000 U.S. adult participants.
To analyze the outcomes of drinking caffeinated coffee, the scientists categorized consumption as 0 cups per day, 1 cup per day, 2 cups per day, and 3 cups or more per day.
The authors found that in all three studies, people who reported drinking one or more cups of caffeinated coffee had an associated decreased long-term heart failure risk.
In FHS and CHS studies, the risk of heart failure over the course of decades decreased by 5-to-12% per cup per day of coffee, compared with no coffee consumption.
In the ARIC study, the risk of heart failure did not change between 0 to 1 cup per day of coffee; however, it was about 30% lower in people who drank at least 2 cups a day.
Drinking decaffeinated coffee appeared to have an opposite effect on heart failure risk — significantly increasing the risk of heart failure in the FHS study. In CHS study however; there was no increase or decrease in risk of heart failure associated with drinking decaffeinated coffee.
When the researchers examined this further, they found caffeine consumption from any source appeared to be associated with decreased heart failure risk, and caffeine was at least part of the reason for the apparent benefit from drinking more coffee.
“The association between caffeine and heart failure risk reduction was surprising,” Dr. Kao said.
“Coffee and caffeine are often considered by the general population to be ‘bad’ for the heart because people associate them with palpitations, high blood pressure, etc.”
“The consistent relationship between increasing caffeine consumption and decreasing heart failure risk turns that assumption on its head.”
“However, there is not yet enough clear evidence to recommend increasing coffee consumption to decrease risk of heart disease with the same strength and certainty as stopping smoking, losing weight or exercising.”