A recent body of literature has suggested that moderate coffee consumption "may be inversely associated with cardiovascular events," the authors state.
In recent months, Medical News Today have reported on a number of studies finding potential health benefits in regular coffee consumption. Moderate coffee consumption has been associated with reduced risks of multiple sclerosis (MS), endometrial cancer and melanoma skin cancer.
Despite this, the study authors state that the effect of coffee consumption on cardiovascular health has remained "controversial." A recent meta-analysis of 36 studies demonstrated that moderate coffee consumption was linked to a decreased risk of heart disease, and other research has made associations with a reduced risk of type 2 diabetes.
In contrast, moderate coffee consumption has also been associated with increased cholesterol concentrations and hypertension. Due to these inconsistent results, the researchers decided to examine levels of coronary artery calcium - a predictor of coronary heart disease - in connection with coffee consumption.
Specifically, the presence of coronary artery calcium can indicate the early stages of coronary atherosclerosis, a condition whereby the arteries become clogged up, hardened and narrow. When this occurs, arteries are more susceptible to blood clots that can lead to heart attacks or strokes.
Researchers led by the Kangbuk Samsung Hospital in Seoul, Korean Republic, analyzed participants attending a regular health screening, including food frequency questionnaires and CT scanning to determine coronary artery calcium. The participants had an average age of 41 and no signs of heart disease.
Coffee consumption was categorized into the following groups:
- No coffee consumed
- Less than one cup a day
- 1-3 cups a day
- 3-5 cups a day
- Five or more cups a day.
The researchers also took potential confounding factors into account when comparing coffee consumption with coronary artery calcium levels, including physical activity participation, smoking status, other dietary components and possible family history of cardiovascular disease.
A U-shaped association
Among the participants, the prevalence of detectable coronary artery calcium was 13.4%. Average coffee consumption was 1.8 cups a day. The researchers observed the following calcium ratios for each group:
- Less than one cup a day: 0.77
- 1-3 cups a day: 0.66
- 3-5 cups a day: 0.59
- Five or more cups a day: 0.81.
In subgroups defined by different variables such as age, alcohol consumption and diabetes status, the association found was similar, suggesting the participants that consumed between three and five cups of coffee a day had the lowest prevalence of clogged arteries.
"Our study adds to a growing body of evidence suggesting that coffee consumption might be inversely associated with CVD [cardiovascular disease] risk," write the study authors. As a cross-sectional study, the authors suggest that further studies will be required to determine biological causation.
They believe that their findings may be explained by the association between coffee consumption and a reduced risk of type 2 diabetes, as diabetes is in turn a risk factor for atherosclerosis. The authors also suggest that coffee drinking may, in addition, improve insulin sensitivity and beta-cell function.
Victoria Taylor, a senior dietitian with the British Heart Foundation (BHF), agrees that the findings of the study will require further investigation. "We need to take care when generalizing these results because it is based on the South Korean population, who have different diet and lifestyle habits to people in the UK," she suggests.
Last year, Medical News Today reported on a study suggesting that different people's coffee drinking habits could be driven by genetics.