Summary
Cardiovascular disease risk
Cardiovascular disease risk
Recent evidence suggests that there is no overall association between moderate coffee intake and coronary heart disease (CHD). In fact, habitual moderate coffee drinking has been associated with a lower risk of CHD in women.
In addition, there does appear to be a small inverse association between coffee drinking and risk of stroke in women only. This negative association is especially strong in women who are past smokers or who have never smoked.
Cardiovascular disease risk factors
The precise nature of the relationship between coffee intake and blood pressure is unclear.
Coffee constituents other than caffeine are responsible for the total and LDL-cholesterol raising effect of coffee. However, these constituents are found in boiled coffee and not filtered.
A small number of preliminary studies have shown a short-term effect of coffee on arterial dilation. Further studies are needed before conclusions can be drawn.
Although there is some evidence to suggest that high coffee intakes increase blood homocysteine, the relationship between high homocysteine levels and cardiovascular disease risk is unclear.
Mechanisms
The mechanisms underlying the associations seen between coffee consumption and reduced risk of stroke, and potential associations with risk factors for coronary heart disease (i.e. cholesterol and blood vessel dilation), need further investigation.
- It is likely that caffeine is not solely responsible for the effect.
- Other coffee constituents, such as cafestol, potassium and polyphenols, may also play a role.
- Other coffee constituents, such as cafestol, potassium and polyphenols, may also play a role.
The scale of the issue
Cardiovascular disease (CVD) is Europe’s number one killer responsible for 54% of all deaths in women and 43% of all deaths in men[1]. In Europe alone, CVD is responsible for the deaths of 4.35 million people annually[2] and costs the EU economy €192 billion Euros per year[3].
A role for diet and lifestyle
Cardiovascular disease is a multi-factorial disease with a wide variety of risk factors, such as high blood pressure, diabetes, smoking and high serum cholesterol. Heredity plays a role in coronary heart disease and stroke, but both are largely influenced by lifestyle factors such as diet, physical activity and smoking.
Regular coffee consumption does not increase risk of cardiovascular disease
A wide variety of studies, both large and small, have been carried out on both healthy participants and patients who already suffer from cardiovascular disease or one of its risk factors. Overall there is no evidence to suggest a negative effect of moderate coffee consumption on cardiovascular health.
Coffee consumption and coronary heart disease risk
A large meta-analysis of 21 studies published in 2009[4] on coffee consumption and coronary heart disease risk found a large variation between the individual results of the studies reviewed. Overall, it did not find a statistically significant association between coffee drinking and long-term risk of coronary heart disease. However, habitual moderate coffee consumption was shown to be associated with a lower risk of heart disease in women.
Three further recent studies[5, 6, 7] also saw no association between coffee consumption and risk of coronary heart disease. In fact, a Dutch study[5] found the lowest risk in groups habitually consuming 2-3 cups of coffee a day.
In conclusion, the large majority of individual studies find no association between coffee consumption and coronary heart disease. However, there is considerable variation between the studies.
Coffee consumption does not increase risk of strokeThe largest study to look at coffee consumption and stroke, the US Nurses Health Study[8], found a statistically significant inverse association between consumption of coffee and stroke incidence. This association was the strongest in the subgroup of former and non-smokers. However, these results have not been corroborated by other studies which have failed to find any associations between coffee intake and stroke incidence [5, 6, 9].
Coffee consumption and blood pressure
The precise nature of the relationship between coffee and blood pressure is still unclear; most evidence would suggest that regular intake of caffeinated coffee does not increase the risk of hypertension.
A large 2008 review[10] of the effect of habitual coffee consumption on blood pressure showed that some studies found a protective effect of coffee whereas others found a small elevation in blood pressure (1-2 mmHg) with a coffee intake of about 5 cups a day compared with abstinence or consumption of decaffeinated coffee.
Coffee consumption and cholesterol – effect of brewing method
The overall evidence would indicate that coffee’s effect on cholesterol levels is largely dependent on the method of brewing. The coffee component cafestol, and to a lesser extent kahweol, raise the serum levels of both total and LDL-cholesterol[11]. However, these components only pass into the brew in so-called ‘boiled’ coffee, but are retained in the filter paper in ‘filtered’ coffee.
A 2001 meta-analysis[12] concluded that trials using filtered coffee demonstrated very little increase in serum cholesterol levels. Interestingly, a more recent study comparing the effects of no coffee versus 4 cups of filtered, and 8 cups of filtered, coffee per day found that filtered coffee raised both total and HDL-cholesterol levels somewhat[13]. Further studies are required to definitively establish coffee’s effects on cholesterol.
Coffee consumption and blood flow
So far only small, short-term experiments have been carried out looking at the effects of coffee on flow-mediated dilation in the brachial artery[14, 15]. These observed a 22% reduction in flow-mediated dilation after consumption of a cup of caffeinated espresso. Larger studies are required before any implications of this short-term vasoconstrictor effect can be assessed.
Coffee consumption and blood homocysteine
There is some evidence from intervention studies that high levels of coffee consumption (6 to 10 cups of coffee per day) increase blood homocysteine levels[16, 17]. However, it is still unclear whether reducing high homocysteine levels will lead to a lower risk of cardiovascular disease. In addition, no causal relationship has been established between high blood homocysteine levels and cardiovascular disease[18].
Studies in patients with underlying disease conditions, from diabetes to myocardial infarction and hypertension, have shown a wide variety of results for the effects of coffee consumption on cardiovascular disease risk.
All the studies show that there are a great number of confounding factors at work which can potentially affect study results, including type of coffee given, genetics of participants and possible biochemical effects of other coffee components. Additionally, inherent difficulties in recruiting diseased participants can mean studies tend to have small numbers of subjects and ongoing patient treatment can interfere with trials. The primary value of in-patient studies will ultimately be in therapy development.
In the past, it was thought that any effect of coffee on the cardiovascular system was likely to be due to caffeine. Many studies only actually tested for the effect of caffeine. Recently the picture has changed.
Boiled coffee’s effect of raising serum total and LDL-cholesterol levels is generally accepted to be due to the coffee oil components cafestol and kahweol. Additionally, studies have found that participants who abstain from, or are used to a low caffeine level, show a short-term rise in blood pressure when given a high caffeine dose in the form of caffeine capsules[19]. This rise of 4 mmHg in this study is far higher than the 1-2 mmHg found with coffee in other studies. This would indicate that in habitual coffee consumers, more factors are involved than just caffeine. Many other substances in coffee, such as polyphenols, soluble fibre and potassium could also have biochemical effects.
The scientific evidence suggests that moderate coffee drinking does not increase the risk of cardiovascular disease. Although coffee consumption has been linked to small effects on cardiovascular disease risk factors, the mechanisms underlying these effects need further investigation.
[1] European Cardiovascular Disease Statistics (2008) European Heart Network, Brussels
[2] Petersen S, Peto V, Rayner M, Leal J, Luengo-Fernandez R, Gray A (2005) European cardiovascular disease statistics. BHF: London.
[3] BHF (2010), Economic costs of CVD in Europe, Coronary Heart Disease Statistics, Chapter 6
[4] Wu J et al. (2009), Coffee consumption and the risk of coronary heart disease: a meta-analysis of 21 prospective cohort studies Int J Cardiol, 137: 216-225.
[5] de Koning Gans J M et al. (2010), Tea and coffee consumption and cardiovascular morbidity and mortality. Arterioscler Thromb Vasc Biol, 30.
[6] Sugiyama K et al. (2010), Coffee consumption and mortality due to all causes, cardiovascular disease, and cancer in Japanese women. J Nutr, 140(5):1007-13.
[7] Ahmed H N et al. (2009), Coffee consumption and risk of heart failure in men: an analysis from the cohort of Swedish men, Am Heart J, 158:667-72.
[8] Lopez-Garcia E et al. (2009), Coffee consumption and risk of stroke in women Circulation, 119:1116-1123.
[9] Leurs L J et al. (2010), Total fluid and specific beverage intake and mortality due to ID and stroke in the Netherlands cohort study. Br J Nutr, 104: 1212-1221.
[10] Geleijnse J M. (2008), Habitual coffee consumption and blood pressure: An epidemiological perspective. Vasc Health Risk Man, 4(5):963-970.
[11] Urgert R& Katan MB. (1996), The cholesterol-raising factor from coffee beans. J R Med, 89(11):618-623
[12] Jee S H et al. (2001), Coffee consumption and serum lipids: a meta-analysis of randomized controlled clinical trials Am J Epidemiol, 153:353-62.
[13] Kempf K et al. (2010), Effects of coffee consumption on subclinical inflammation and other risk factors for type-2 diabetes: a clinical trial. Am J Clin Nutr, 91:950-7.
[14] Buscemi S et al. (2010), Coffee and endothelial function: a battle between caffeine and antioxidants. European Journal of Clinical Nutrition, 64:1242-1243.
[15] Buscemi S et al. (2010), Acute effects of coffee on endothelial function in healthy subjects. European Journal of Clinical Nutrition 64:483-489.
[16] Grubben M J et al. (2000), Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: a randomized trial. American Journal of Clinical Nutrition, 71:480 -484.
[17] Urgert R A et al. (2000), Heavy coffee consumption and plasma homocysteine: a randomized controlled trial in healthy volunteers. American Journal of Clinical Nutrition, 72:1107-1110.
[18 ] Higdon J V & Frei B. (2006), Coffee and Health: A Review of Recent Human Research. Critical Reviews Food Science and Nutrition, 46:101-123.
[19] Farag N H et al. (2010), Caffeine and blood pressure response, sex, age, and hormonal status. J Women’s Health, 19(6):1171-6.
[2] Petersen S, Peto V, Rayner M, Leal J, Luengo-Fernandez R, Gray A (2005) European cardiovascular disease statistics. BHF: London.
[3] BHF (2010), Economic costs of CVD in Europe, Coronary Heart Disease Statistics, Chapter 6
[4] Wu J et al. (2009), Coffee consumption and the risk of coronary heart disease: a meta-analysis of 21 prospective cohort studies Int J Cardiol, 137: 216-225.
[5] de Koning Gans J M et al. (2010), Tea and coffee consumption and cardiovascular morbidity and mortality. Arterioscler Thromb Vasc Biol, 30.
[6] Sugiyama K et al. (2010), Coffee consumption and mortality due to all causes, cardiovascular disease, and cancer in Japanese women. J Nutr, 140(5):1007-13.
[7] Ahmed H N et al. (2009), Coffee consumption and risk of heart failure in men: an analysis from the cohort of Swedish men, Am Heart J, 158:667-72.
[8] Lopez-Garcia E et al. (2009), Coffee consumption and risk of stroke in women Circulation, 119:1116-1123.
[9] Leurs L J et al. (2010), Total fluid and specific beverage intake and mortality due to ID and stroke in the Netherlands cohort study. Br J Nutr, 104: 1212-1221.
[10] Geleijnse J M. (2008), Habitual coffee consumption and blood pressure: An epidemiological perspective. Vasc Health Risk Man, 4(5):963-970.
[11] Urgert R& Katan MB. (1996), The cholesterol-raising factor from coffee beans. J R Med, 89(11):618-623
[12] Jee S H et al. (2001), Coffee consumption and serum lipids: a meta-analysis of randomized controlled clinical trials Am J Epidemiol, 153:353-62.
[13] Kempf K et al. (2010), Effects of coffee consumption on subclinical inflammation and other risk factors for type-2 diabetes: a clinical trial. Am J Clin Nutr, 91:950-7.
[14] Buscemi S et al. (2010), Coffee and endothelial function: a battle between caffeine and antioxidants. European Journal of Clinical Nutrition, 64:1242-1243.
[15] Buscemi S et al. (2010), Acute effects of coffee on endothelial function in healthy subjects. European Journal of Clinical Nutrition 64:483-489.
[16] Grubben M J et al. (2000), Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: a randomized trial. American Journal of Clinical Nutrition, 71:480 -484.
[17] Urgert R A et al. (2000), Heavy coffee consumption and plasma homocysteine: a randomized controlled trial in healthy volunteers. American Journal of Clinical Nutrition, 72:1107-1110.
[18 ] Higdon J V & Frei B. (2006), Coffee and Health: A Review of Recent Human Research. Critical Reviews Food Science and Nutrition, 46:101-123.
[19] Farag N H et al. (2010), Caffeine and blood pressure response, sex, age, and hormonal status. J Women’s Health, 19(6):1171-6.
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