Dr Martin Juneau, M.D., FRCP

Cardiologue, directeur de l'Observatoire de la prévention de l'Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention Watch, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.

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The effects of coffee on cardiovascular disease

Updated on July 13, 2018

A recent study published in Nature Medicine suggests that coffee consumption may protect the heart and blood vessels due to the anti-inflammatory effect of caffeine. As we age, a slowing metabolism, combined with increased oxidative stress, causes the body to accumulate several inactive metabolites that are considered toxic to the immune system and activate the inflammatory response. Chronic inflammation is very harmful to the cardiovascular system, as it promotes the progression of several phenomena that damage the heart and blood vessels, such as atherosclerosis, hypertension and insulin resistance. Researchers have observed that people who regularly consume caffeinated drinks, particularly coffee, produce less of these inflammatory metabolites, have more elastic blood vessels, and are on average healthier.

These results are in line with several epidemiological studies showing that regular coffee consumption is associated with the reduced risk of cardiovascular disease and mortality in general. For example, a meta-analysis of studies involving 1,279,804 participants found that people who consumed a moderate amount of coffee (3 to 5 cups per day) were about 15% less likely to be affected by cardiovascular disease (coronary heart disease and stroke) than people who never drank coffee.

Several studies have also shown that coffee consumption is safe for people with established coronary heart disease. For example, a randomized clinical trial involving patients who had suffered a heart attack with acute ST-segment elevation (STEMI) showed that coffee consumption (4 to 5 cups per day, for a caffeine intake of 353 mg) did not cause arrhythmia and was not associated with any cardiovascular disorder. These observations are consistent with other studies showing that coffee consumption is not associated with the development of arrhythmias such as atrial fibrillation, and may even be associated with a decreased risk of such events.

Coffee also does not seem to have any major effects on blood pressure, although caffeine is known to stimulate the sympathetic nervous system. Studies show that, in individuals who never drink coffee, caffeine can indeed cause a short-term increase in blood pressure (by about 10 mm Hg), but the effect is transient and disappears completely in regular drinkers due to the phenomenon of tolerance. The absence of the long-term hypertensive effect of coffee was confirmed by a study involving 155,594 women showing that the regular consumption of coffee, even in high amounts (6 cups per day), is not associated with an increased risk of hypertension. However, the same study reported that the consumption of other sources of caffeine such as soft drinks (regular and diet) is associated with an increased risk of high blood pressure, suggesting that there are other compounds in coffee that may offset the effect of caffeine on blood pressure. Indeed, it is interesting to note that the intravenous administration of caffeine increases blood pressure even among regular coffee drinkers, while the consumption of the beverage itself has no impact. Overall, this data suggests that the neutral effect of coffee on blood pressure is due to the presence of molecules that reduce caffeine’s stimulation of the sympathetic nervous system. This is not surprising considering that coffee is not merely a source of caffeine, but rather a highly complex beverage containing more than a thousand distinct compounds, including several antioxidant and anti-inflammatory molecules.

Studies show that some of these molecules, such as chlorogenic acids and lignans, may also contribute to improving sugar metabolism and thus prevent type 2 diabetes. For example, an analysis of a dozen studies on the relationship between coffee consumption and the risk of type 2 diabetes shows that people who drank 4–6 cups a day were about 30% less likely to develop the disease compared to those who drank it very little or never. A prospective study involving 88,000 women aged 26 to 46 suggests that the protective effect of coffee may be even greater, and can be observed for smaller amounts of coffee, with a 13% and 42% reduction in risk for a daily consumption of 1 cup and 2–3 cups, respectively. These reductions are also observed for decaffeinated coffee, suggesting that, beyond caffeine, the molecules contained in this beverage can help maintain normal blood sugar levels.

Several recent studies also indicate that regular coffee consumption is associated with a decreased risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, several types of cancer, particularly liver cancer, a decreased risk of recurrence in people who have been affected by hormone-dependent breast and colon cancer, a decreased risk of end-stage renal disease, and a decreased risk of premature death. Coffee’s long-standing reputation as unhealthy is therefore irrelevant. While it is notably appreciated for its stimulating properties, coffee is a drink that has many positive effects, not only for preventing cardiovascular disease but also on health in general.

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