How Coffee Affects Health

Coffee is the second most consumed beverage in the United States behind water, and it is one of the most widely consumed beverages worldwide (O’Keefe et al. 2013). Over the past several decades, researchers have studied the effects of coffee consumption on cardiovascular health because even small effects may have a significant impact on public health given the beverage’s popularity. Previous studies have yielded mixed results as to whether coffee consumption is beneficial or harmful to cardiovascular health, leading to many misconceptions that persist today.

The good news for coffee drinkers is that recent studies have consistently linked coffee consumption with a lower risk of mortality from cardiovascular disease (CVD), coronary heart disease, and stroke (Poole et al. 2017). In a 2020 study from Japan, increased coffee intake was associated with a decreased risk of all-cause mortality in both men and women. Mortality from stroke was reduced only in men, however, while mortality from heart disease was reduced only in women (Sado et al. 2020). Another 2020 study using data from the Norwegian Women and Cancer Study had similar results, with coffee intake of 4 to 6 cups/day associated with a 21% lower risk of death from CVD when compared with coffee intake of <1 cup/day (Lukic et al. 2020).

Moderate coffee consumption has also been associated with a lower risk of heart failure. When compared to those who did not drink coffee, people who drank an average of 4 cups/day had an 11% reduced risk of developing heart failure. Intake of ≥10 cups/day resulted in a return to the baseline risk level (Mostofsky et al. 2012).

Hypertension, or high blood pressure, is a known risk factor for CVD, stroke, and heart failure. Experimental studies have repeatedly demonstrated that coffee is associated with acute increases in blood pressure, partially due to higher circulating concentrations of norepinephrine and epinephrine and greater arterial stiffness (Mostofsky et al. 2012). But these effects appear to diminish over time with regular coffee consumption (O’Keefe et al. 2013).

Other studies have found that increased coffee consumption may decrease the risk of developing type 2 diabetes, which is yet another risk factor for CVD, stroke, and heart failure (O’Keefe et al. 2013, Poole et al. 2017). Conversely, coffee has been shown to have a negative effect on blood lipids, with higher levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides associated with increased coffee intake. These effects, though, appear to be mitigated when filtered coffee is consumed rather than boiled coffee (Poole et al. 2017).

So how can coffee have such effects?

Apart from caffeine, coffee contains other bioactive compounds such as chlorogenic acids, cafestol, and kahweol, all of which contribute to coffee’s impact on cardiovascular health (Farias-Pereira et al. 2019). Chlorogenic acid and caffeine act as antioxidants and have been shown to increase insulin sensitivity and glucose metabolism, thus decreasing the risk of type 2 diabetes (O’Keefe et al. 2013, Poole et al. 2017). The diterpenes cafestol and kahweol may similarly act as antioxidants and inflammatory mediators, though they are also responsible for the undesirable effect of increasing one’s serum cholesterol by reducing bile acid synthesis (Farias-Pereira et al. 2019, Lukic et al. 2020).

Coffee Composition Varies

The composition of coffee, and thus its effects, can vary greatly depending on the types of beans and the methods of roasting and brewing used (Farias-Pereira et al. 2019). For instance, some estimate that the amount of caffeine in a given 8 fl oz cup of coffee can range from 95 to 200 mg (O’Keefe et al. 2013), and both caffeine and diterpenes are found in higher concentrations in boiled coffee than in filtered coffee (Lukic et al. 2020). In preparing filtered coffee, many of the diterpenes are caught by the filter paper, which is why their cholesterol-raising effects are seen only with boiled coffee intake. Light and medium roast coffees are generally higher in chlorogenic acids than dark roast coffees because roasting degrades the compound (Farias-Pereira et al. 2019, Poole et al. 2017).

In sum, moderate coffee consumption of 3–4 cups/day appears to have a beneficial effect on mortality from CVD, stroke, and heart failure. While recent studies have been able to shed some light on the biological mechanisms behind these effects, the specifics are poorly understood. Further research is needed to determine whether other forms of coffee, such as espresso, instant, and decaffeinated coffee, have similar effects.