Understanding Caffeine, Coffee, & Cardiovascular Disease

By Glenn / January 18, 2015

COFFEE AND CARDIOVASCULAR DISEASE

Cardiovascular disease (CVD), coronary heart disease, is the number one cause of death in America. It has been the subject of extensive medical and scientific research for several decades.

While researchers have differed in their conclusions over time, new evidence  strongly indicates that consumption of coffee and caffeine does not contribute to CVD, finding neither caffeinated nor decaffeinated coffee associated with the risk of stroke—even for those drinking more than four cups of coffee a day. (13)

Warren G. Thompson, M.D., noted in a 1994 literature review on this subject: "The largest and better studies suggest that coffee is not a major risk factor for coronary disease." (1)

Willet et. al, in a prospective study reported in the February 1996 issue of the Journal of the American Medical Association (JAMA), examined data collected from more than 85,000 women over a 10-year period. After adjusting for known risk factors, the authors found no evidence for any positive association between coffee consumption and risk of CVD for women consuming six or more cups of coffee a day. (2)

A 1990 study of more than 45,000 men found no link between coffee, caffeine and CVD for those drinking four or more cups of coffee a day. (3)

These results confirm findings from the earlier Framingham Heart Study of more than 6,000 adults conducted over 20 years (4) and two 1987 studies using data from the Honolulu Heart Program. (5, 6)


Following are frequently asked questions and answers about Coffee and Cardiovascular Disease

Q1: Does coffee consumption increase serum lipids/cholesterol levels, which sometimes leads to CVD?

A: Studies of individuals drinking coffee prepared by drip machines and percolators find little or no effect on cholesterol. Studies from Scandinavia using boiled unfiltered coffee — a process little used in the U.S. — have found a worsening effect on serum lipids. Thus, the differences in brewing processes utilized in the various countries explain the original difference. Consumption of coffee typically prepared in the U.S. does not effect blood cholesterol levels.


Q2: Does coffee/caffeine consumption contribute to high blood pressure/hypertension, which sometimes leads to CVD?

A: Despite previous controversy on the subject, most researchers now conclude that regular coffee and caffeine use has little or no effect on blood pressure.

Studies indicate that while first-time caffeine use may produce immediate, minimal changes in blood pressure, these changes are transient. (7) No changes in blood pressure appear to occur in regular users of caffeine. A 1991 study reached the same conclusion and indicated that restricting caffeine did not reduce blood pressure in people with mild hypertension. (8) A number of studies that have looked at people with normal blood pressure have concluded that caffeine does not contribute to hypertension. (4, 9, 10)

In 1997, the Sixth Report of the National Institutes of Health's Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure concluded that, "no direct relationship between caffeine intake and elevated blood pressure has been found in most epidemiologic surveys." (12)


Q3: What is heart arrhythmia and how is it affected by caffeine consumption?

A: Heart arrhythmias are irregularities of the heartbeat. A growing body of research indicates that the heartbeat irregularities are not affected by coffee and caffeine consumption for the vast majority of individuals, both healthy individuals and those with heart disease.

In a 1991 article reviewing virtually all research on coffee, caffeine and arrhythmias, Martin G. Meyers, M.D., concluded that the ingestion of 500 mg of caffeine, the equivalent of five to six 8-ounce cups of coffee a day, does not increase the frequency or severity of cardiac arrhythmias or ventricular tachycardia (increased heart rate) in healthy people or those with CVD. (11)


Q4: Does coffee/caffeine consumption decrease an individual's tolerance for or ability to exercise?

A: Researchers have found that coffee/caffeine consumption has little or no effect on exercise tolerance in healthy people or those with CVD. In fact, some studies have found that consuming caffeine has a positive effect on exercise performance, increasing both energy and endurance.


Q5: Does coffee/caffeine consumption contribute to high homocysteine levels, which some consider a factor in CVD?

A: Recent claims that an association between coffee consumption and homocysteine is linked to cardiovascular disease are not supported by 16 major studies in the scientific literature—which examined heavy coffee consumption and all forms of cardiovascular disease and found no relationship.

There is clear evidence that high homocysteine levels are linked to poor nutrition, in particular, deficient levels of folate and vitamins B6 and B12 (11-14). In a 1998 study which claimed an adverse effect on homocysteine levels from coffee consumption, the lead scientist stated, "the largest variation in plasma total homocysteine was observed in subjects with low intakes of dietary folate, mostly determined by fruit and vegetable intake."

Influence of diet may explain why the 1989 Atherosclerosis Risk in Communities Study (ARIC) in the United States found no association between coffee consumption and plasma homocysteine levels. Likewise, more recent research in 1999 demonstrated that people with sound diets showed no effect on their plasma homocysteine levels from all forms of coffee consumption.

At the same time, a comprehensive review of homocysteine research—examining 43 studies published between 1966 and 1998—concluded that prospective studies indicated little or no association between high homocysteine levels and cardiovascular disease, casting serious doubt as to whether homocysteine is a risk factor for CVD. (14)


REFERENCES FOR UNDERSTANDING COFFEE, CAFFEINE AND CARDIOVASCULAR DISEASE

1. Thompson, Warren G., "Coffee: Brew or Bane?," The American Journal of Medical Sciences. 308:49-57, 1994.

2. Willet, Walter C. et al., "Coffee Consumption and Coronary Heart Disease in Women," JAMA. 275:458-462, 1996.

3. Grobbee, Diedrick E. et al., "Coffee, Caffeine and Cardiovascular Disease in Men," New England Journal of Medicine. 323:1026-1032, 1990.

4. Wilson, P.W.R. et al., "Is Coffee Consumption a Contributor to Cardiovascular Disease? Insights from the Framingham Study," Archives of Internal Medicine. 149:1169-1172, 1989.

5. Yano K. et al., "Coffee Consumption and the Incidence of Coronary Heart Disease," New England Journal of Medicine. 316: 946, 1987.

6. Reed, D.M. et al., "Predictors of Atherosclerosis in the Honolulu Heart Program," American Journal of Epidemiology. 126:214-225, 1987.

7. Rosmarin, Philip C., "Coffee and Coronary Heart Disease: A Review," Progress in Cardiovascular Diseases. 32:239-245, 1989.

8. MacDonald, T.M. et al., "Caffeine Restriction: Effect on Mild Hypertension," British Medical Journal. 303: 1235-1238, 1991.

9. Committee on Diet and Health, Food and Nutrition Board, Diet and Health: Implications for Reducing Chronic Disease Risk. Washington, DC: National Academy Press; 11-12, 1989.

10. Bak, Annette AA and Grobbee, Diederick, "Caffeine, Blood Pressure and Serum Lipids," American Journal of Clinical Nutrition. 53: 971-974, 1991.

11. Meyers, M. G., "Caffeine and Cardiac Arrhythmias," Annals of Internal Medicine. 114:147-50, 1991.

12. Sixth Report of the NIH Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. Washington, DC: NIH Publication 98-4080, November 1997.

13. Sesso et al, "Coffee and tea intake and the risk of myocardial infarction," American Journal of Epidemiology, 149 (2): 162-167, January 1999.

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