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Four Cups of Coffee A Day Decreases Stroke Risk in Women
A new analysis of data from the Nurses’ Health Study shows that long-term intake of up to four or more cups of coffee per day was not associated with an increased risk for stroke and actually appeared to be protective against stroke in women who did not also smoke.
Among women who currently smoked, there appeared to be no effect of coffee intake, neither raising nor lowering stroke risk. No association was seen with other caffeinated drinks, including tea or soft drinks, and decaffeinated coffee still showed a trend toward a protective effect.
Ester Lopez-Garcia, PhD, from the Universidad Autonoma de Madrid, Spain, and colleagues at the Harvard School of Public Health, conclude, “Our data support the hypothesis that components in coffee other than caffeine may lower the risk for stroke, although the association was modest and the biological mechanism is unclear.”
Recently reported data have suggested that coffee does not increase the risk for coronary heart disease and may be protective against type 2 diabetes, the authors write. Data on the relationship of coffee intake and stroke are “sparse” they note, and have been somewhat contradictory.
In this study, they analyzed data from the Nurses’ Health Study, a prospective cohort of 83,076 women who were free of stroke, coronary heart disease, diabetes, or cancer at baseline. Coffee consumption was assessed first in 1980 and then every two to four years thereafter, with follow-up during 24 years through 2004.
During this period, 2,280 strokes occurred among the women; 1,224 ischemic strokes, 426 hemorrhagic strokes, and 630 strokes of undetermined cause.
After adjustment for factors including age, smoking status, body mass index, physical activity, alcohol intake, menopausal status, hormone therapy, aspirin use, and dietary factors, they found no increase in the risk for stroke associated with increasing coffee intake, and evidence for a protective effect for intakes of two or more cups per day vs less than one cup per month (P for trend = .003)
Relative Risk of Stroke With Increasing Coffee Intake
Coffee Intake (Cups)
Relative Risk
95% CI
< 1/month
1.0 (Referent)
1/month – 4/week
0.84 – 1.15
5 – 7/week
0.77 – 1.02
2 – 3/day
0.70 – 0.95
≥ 4/day
0.64 – 0.98
After further adjustment for high blood pressure, hypercholesterolemia, and type 2 diabetes, the inverse association remained significant, the authors noted.
Because cigarette smoking is more common in coffee drinkers and a strong confounder of stroke risk, they stratified the data by smoking status. They found that the association was stronger among never or past smokers than among current smokers, suggesting that “the potential benefit of coffee consumption cannot counterbalance the detrimental effects smoking has on health,” the authors write.
Relative Risk of Stroke With Increasing Coffee Consumption by Smoking Status
Smoking Status
Relative Risk (≥ 4 Cups/Day vs < 1 Cup/Month)
95% CI
Never or past smokers
0.39 – 0.84
Current smokers
0.63 – 1.48
Other drinks containing caffeine, including tea and caffeinated soft drinks, were not associated with stroke, they note. Decaffeinated coffee was associated with a trend toward lower stroke risk after adjustment for consumption of caffeinated coffee (relative risk, 0.89 for 2 or more cups per day vs less than 1 per month; 95% CI, 0.73 – 1.08; P for trend = .05).
More research will be required before implications for public health and clinical practice are considered, the authors write. However, there does not at least appear to be any risk for stroke associated with coffee intake for those who already drink it.
In a news release from the American Heart Association, Dr. Lopez-Garcia noted, “Anyone with health problems that can be worsened by coffee (insomnia, anxiety, hypertension, or heart problems) should talk to their doctor about their specific risk.”
Practice Pearls
  • In a previous systematic review, higher levels of coffee consumption were associated with lower rates of elevated postprandial hyperglycemia and incident type 2 diabetes.
  • In the current study, coffee consumption was associated with a modest reduction in the risk for stroke among women.
Circulation. online February 16, 2009