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reference
Mostofsky E, Schlaug G, Mukamal KJ, Rosamond WD, Mittleman MA. Coffee and the onset of acute ischemic stroke: The stroke onset study.Neurology.2010;75(18):1583-1588.
design
Multicenter case-crossover study
Participant
The study was conducted between January 2001 and November 2006 at three medical centers (Boston, Chapel Hill, and Victoria, BC). Trained interviewers interviewed 390 subjects (209 men, 181 women) an average of 3 days after an acute ischemic stroke. Each subject's coffee consumption in the hour before stroke symptoms appeared was compared with their usual frequency of consumption in the previous year.
Study “Medicines and Dosage”
The serving size for a serving of coffee was set at 8 ounces. Similar questions were asked about the consumption of caffeinated tea and cola.
Primary outcome measures
In patients who have suffered an ischemic stroke, consumption and timing of coffee consumption.
Key findings
78 percent of the test subjects drank coffee in the previous year, 59 percent within 24 hours and 9 percent within one hour of the onset of the stroke. The relative risk of stroke doubled in the hour after coffee consumption. No apparent increase in risk was found for caffeinated tea or cola. The association between stroke and coffee was only observed in patients who consumed ≤ 1 cup per day, but not in patients who regularly drank more coffee.
The link between stroke and coffee was only observed in patients who consumed 1 cup per day, but not in patients who drank more coffee regularly.
Effects on practice
Although this study has received widespread public media attention, the context is more complex than is typically reported. The study is just one of several related papers recently published.
The timing of death from heart attack and stroke follows a circadian pattern and peaks after waking in the morning. Psychological stress, physical exertion and simply waking up affect physical parameters such as blood pressure, heart rate, blood flow, endothelial function and adrenaline levels; All upregulate the production of sympathetic catecholamines, thereby increasing the heart's oxygen demand while decreasing oxygen supply. The combination leads to an increased risk of stroke in the morning.1The authors of the current paper believe they designed the study so that these circadian patterns would not influence their results.2
Other studies provide inconsistent data on coffee consumption and stroke risk. Ester Lopez-Garcia et al. reported in their 2009 paper that coffee consumption reduced the risk of stroke. They analyzed data from a cohort of 83,076 women in the Nurses' Health Study across all categories of coffee consumption. Those who drank 2 to 3 cups per day had a 19% reduced risk of stroke (RR 0.81 (95% CI: 0.70 to 0.95)). This association was stronger among non-smokers. Those who drank four or more cups of coffee a day had a 43% lower risk than those who didn't drink coffee regularly.3
Studies have also generally shown that drinking coffee reduces the risk of heart attack. According to an article by Dutch researchers published in August 2010, coffee was clearly associated with lower cardiovascular morbidity and mortality. In their work, 37,514 participants were followed for 13 years. Drinking 2-3 cups of coffee per day reduced the risk of heart disease by 21%. Drinking less or more coffee had a lower protective effect.4
Not all studies report this protection. A study of Swedish coffee drinkers found that coffee increases the risk of heart attack. Lena Nilsson et al. compared coffee consumption in 375 MI cases with 1,293 matched controls and found a statistically significant positive association between filtered coffee consumption and MI risk in men. Those who drank coffee four or more times a day had a 73% increased risk of having a heart attack.5
A previous Swedish study from 2003 found similar results in men. Those who drank 10 dl (~4 cups) had about twice the risk of having a heart attack: a relative risk of 1.93 for filtered coffee and 2.20 for boiled coffee.6
Looking through these various studies, it appears that coffee's "toxicity-dose-response curve" may actually be U-shaped. Low and high levels of consumption may increase the risk, while moderate consumption in the range of 2-3 cups per day may be beneficial.
There is another possible explanation for these inconsistent results. Already in the March 2006 issue ofJAMA, stated Cornelis et al. from the University of Toronto a fair question. Coffee does not affect everyone the same way. Some people are very sensitive - one cup in the morning leaves them sleepless all night. Others drink coffee with dinner and before bed without any ill effects. This variation is genetically determined. The CYP1A2 gene codes for the enzyme that breaks down caffeine. Individuals with a version of this gene are “rapid” caffeine metabolizers. Those who carry another variant are “slow metabolizers.”
In the 2006 Cornelis study, drinking coffee had a different impact on heart attack risk depending on whether people were fast or slow metabolizers. For slow metabolizers, drinking coffee increased the risk of having a heart attack. For people who metabolize quickly, coffee reduced the risk:
For people whose genes make them metabolize coffee quickly, drinking one cup of coffee a day reduces the risk of a heart attack by just over half. On the other hand, the same cup of coffee increases the risk of being a slow metabolizer by about 25%.7
Could it be that we are confused in the current coffee and stroke risk study, as well as these other coffee risk studies, because we do not take into account the different metabolisms of the study participants? For example, in the stroke study under consideration, does it seem more likely that slow metabolizers belong to the group that drinks coffee less often? People who metabolize quickly are more likely to drink more coffee more regularly and are less likely to suffer the side effects of this habit?
Although according to the study by Mostofsky et al. While it is tempting to encourage patients to drink coffee regularly to reduce the risk of stroke and heart disease, there may be more to this story that needs to be published.