More good news for coffee drinkers: a review of existing studies has found that overall, moderate coffee consumption is tied to a much lower risk of chronic disease. However, there are some caveats.
One study, for example, suggested that coffee may drastically reduce the risk of early death in women with diabetes, while one more general study suggested that the beverage can lower the chances of heart failure or stroke.
Another one reported that coffee could halve the risk of premature mortality among those with HIV or hepatitis C. But how reliable are these studies? And, if you combined all of the research done on coffee and pooled together all of their conclusions, what would be the verdict?
New research explores precisely these aspects. The study was led by Dr. Robin Poole, a specialist registrar in public health at the University of Southampton in the United Kingdom, and the findings were published in The BMJ.
‘Largest risk reduction’ at three to four cups
Dr. Poole and colleagues examined 201 meta-analyses of existing observational studies, and 17 meta-analyses of clinical trials.
Overall, the team found that moderate coffee consumption is “more likely to benefit health than to harm it.” Moderate coffee intake is usually considered to be around four or five daily cups, or the equivalent of up to 400 milligrams of caffeine per day.
More specifically, the researchers found that coffee intake was linked with a decrease in the risk of cardiovascular disease, cancer, non-alcoholic fatty liver disease, cirrhosis, and diabetes.
Additionally, the beverage correlated with a lower risk of mortality from all causes, as well as mortality from cardiovascular disease in particular.
“Coffee consumption seems generally safe within usual levels of intake,” write the researchers, “with summary estimates indicating largest risk reduction for various health outcomes at three to four cups a day.”
In fact, three cups of coffee per day lowered the risk of coronary heart disease by 19 percent, and that of mortality from stroke by 30 percent. A high coffee intake was linked with an 18 percent decrease in cancer risk, compared with a low intake.
The greatest risk reduction was noticed for liver cirrhosis: “any versus no coffee consumption” was linked to a 39 percent lower risk of developing this condition.
However, the authors caution that most existing studies on the benefits of coffee are “of lower quality,” as they are merely observational and do not explain causality.
So, the authors urge that “robust randomized controlled trials are needed to understand whether the observed associations are causal.”
‘Coffee is safe, but hold the cake’
In an accompanying editorial, Eliseo Guallar — from the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD — comments on the findings. “Should doctors recommend drinking coffee to prevent disease? Should people start drinking coffee for health reasons? The answer to both questions is ‘no.'”
“The evidence is so robust and consistent across studies and health outcomes, however, that we can be reassured that drinking coffee is generally safe,” he continues.
However, women at risk of bone fractures and those who are pregnant may not derive the same health benefits from coffee, the research revealed.
Finally, Guallar cautions that drinking coffee is sometimes linked with less healthful habits, such as eating sugary cakes or other fatty products. “Coffee is safe, but hold the cake,” he writes.
All in all, however, the benefits seem to outweigh the risks.
“Even with these caveats, moderate coffee consumption seems remarkably safe, and it can be incorporated as part of a healthy diet by most of the adult population.”