A large analysis examined hundreds of factors that may influence the risk of heart failure and found one particular dietary factor that was associated with a lower risk: drinking coffee.
Heart failure, sometimes called congestive heart failure, occurs when the heart muscle is weakened and can no longer pump blood efficiently. It can be caused by high blood pressure, heart valve disease, heart attack, diabetes and other diseases and conditions.
The analysis included extensive data from decades of three major health studies with 21,361 participants and used a method called machine learning that uses computers to find meaningful patterns in large amounts of data.
“Typically, researchers choose things that they suspect are risk factors for heart failure – smoking, for example – and then look at smokers versus non-smokers,” said senior author, Dr. David P. Kao, professor medical assistant at the University of Colorado. “But machine learning identifies variables that are predictive of increased or decreased risk, but that you didn’t necessarily think about.”
Using this technique, Dr. Kao and his colleagues found 204 variables that are associated with the risk of heart failure. Then they analyzed the 41 strongest factors, which included, among others, smoking, marital status, BMI, cholesterol, blood pressure and the consumption of various foods. The analysis is in Circulation: Heart Failure.
In all three studies, coffee consumption was associated more strongly than any other dietary factor with decreased long-term risk of heart failure.
Drinking one cup a day or less had no effect, but two cups a day gave a reduced risk of 31%, and three cups or more reduced the risk by 29%. There were not enough individuals who drank more than three cups a day to see if more coffee would lower the risk even more.
This is not the first study to discover health benefits from coffee consumption. “In other studies, coffee consumption was also associated with a reduced risk of stroke and coronary heart disease,” said Kao, although “we did not find this in our study.”
The study was unable to take into account the different types of coffee or fermentation methods, or the use of additives such as sugar or cream. There was no association between decreased risk of heart failure and consumption of decaffeinated coffee – in fact, one study suggested that this may increase the risk.
Caffeine may be an important factor, the authors suggested, but the mechanism for this is not known. The study did not examine the effect of tea or other foods that contain caffeine.
Unlike conventional observational studies that start with a hypothesis and then develop evidence for it, this machine learning analysis started without any initial hypothesis. Dr Harlan Krumholz, a medical professor at Yale who was not involved in the work, called the approach “innovative”, but noted that a limitation was that “many other behaviors are likely to accompany coffee consumption and it is difficult to separate the specific effect coffee from other things that may come along. ”
Should you start drinking coffee or increase the amount you already drink to reduce your risk of heart failure? “We don’t know enough from the results of this study to recommend this,” said Dr. Kao, adding that further research would be needed. “It would be helpful if we could find out if drinking an extra glass would avoid certain complications.”