Coffee contradictions? Drinking 25 cups a day not linked to stiffer arteries, new research reveals

03 Jun 2019 --- Drinking coffee, including extremely high volume consumption, is not linked with stiffer arteries and is not as bad for the heart and circulatory system as previously thought, according to new research. A study by Queen Mary University of London, partly funded by the British Heart Foundation (BHF), involved 8,412 people in the UK and debunks previous scientific claims that drinking coffee increases arterial stiffness.

Previous suggestions that drinking coffee leads to stiffer arteries are “inconsistent and could be limited by lower participant numbers,” according to the team behind this new research.

“Understanding the impact that coffee has on our heart and circulatory system is something that researchers and the media have had brewing for some time,” says Professor Metin Avkiran, BHF Associate Medical Director.

“There are several conflicting studies saying different things about coffee, and it can be difficult to filter what we should believe and what we shouldn’t. This research will hopefully put some of the media reports in perspective, as it rules out one of the potentially detrimental effects of coffee on our arteries,” he adds. 

The research, which was recently presented at the British Cardiovascular Society (BCS) Conference in England, involved more than 8,000 people in the UK. 

Consumption was categorized into three groups for the study. Those who drink less than one cup a day, those who drink between one and three cups a day and those who drink more than three. 

People who consumed more than 25 cups of coffee a day were excluded, but no increased stiffening of arteries was associated with those who drank up to this extremely high limit when compared with those who drank less than one cup a day, according to the research. Contributing factors like age, gender, ethnicity, smoking status, height, weight, alcohol consumption, diet and high blood pressure were all taken into consideration. 

As the body of research examining the pros and cons of coffee consumption grows, there continues to be a mixed bag of findings raising questions over which advice to follow. 

Last month, a study from the University of South Australia (UniSA), published in The American Journal of Clinical Nutrition, claimed that consuming six or more coffees a day may increase the risk of heart disease by up to 22 percent. 

This study marked the first time an upper limit has been placed on safe coffee consumption in relation to cardiovascular health. The researchers note that more research on the matter is warranted to determine whether other aspects of health are affected by coffee consumption and also to determine the varied individual responses to caffeine.

The bright side of dark roast
Last month the purgative properties of coffee were examined in a US study which pinpointed the specific reason or mechanism why coffee is associated with accelerated bowel movement. 

“Despite the huge popularity of coffee worldwide, different reports could put people off from enjoying it. While we can’t prove a causal link in this study, our research indicates coffee is not as bad for the arteries as previous studies would suggest,” adds Dr. Kenneth Fung, who led the data analysis for the research. 

“Although our study included individuals who drink up to 25 cups a day, the average intake among the highest coffee consumption group was five cups a day. We would like to study these people more closely in our future work so that we can help to advise safe limits.”

The morning staple loved around the world is, however, also linked to several beneficial health outcomes, according to emerging science. Certain compounds found in coffee, called phenylindanes, may hinder two protein fragments responsible for Alzheimer’s and Parkinson’s from clumping, therefore potentially aiding in the prevention of these diseases, researchers from the Krembil Brain Institute have found.

In addition, certain coffee compounds may inhibit the growth of prostate cancer, according to a recent pilot study, carried out on drug-resistant cancer cells in cell culture and in a mouse model.

Another study from last April also says that light roast coffee holds anti-cancerous properties that darker roast coffee does not. The study, published in The Journal of Food Science, compared coffee roasted at five different levels, against the growth inhibitory activity of cancer cells that are associated with oral and colon cancers.

One point that is not in debate, however, is that more work is needed to establish the full range of potential health benefits and risks associated with coffee consumption.