Higher coffee consumption is inversely
associated with risk of CVD and stroke in the general population.
Coffee is one of
the most extensively researched components in the diet. New studies are
regularly being added to the already large body of scientific research, which
overall suggests that moderate habitual coffee consumption is not associated
with detrimental effects on cardiovascular health
Among recent
studies, a new review paper1 highlights that for most healthy people, moderate
coffee consumption is unlikely to adversely affect cardiovascular health.
Furthermore a new paper2 concluded that higher green tea and coffee consumption
is inversely associated with risk of CVD and stroke in the general population.
Considerable
research has also been devoted to investigating associations between coffee
consumption and key risk factors for cardiovascular disease, such as
hypertension (high blood pressure) and elevated cholesterol. Most evidence
suggests that regular moderate consumption of caffeinated coffee has no
long-term effect on blood pressure and does not increase the risk of
hypertension.
A recent study
suggests that moderate consumption of paper-filtered coffee may have an
unfavourable effect on plasma cholesterol3. The wider body of evidence
indicates that the impact of coffee on cholesterol is dependent on the brewing
method. Unfiltered coffee raises serum cholesterol levels whereas this is not
the case with filter coffee because the cholesterol-raising compounds in coffee
are retained in the paper filter.
Throughout 2013
coffee and mortality has been a subject of several scientific research papers,
which have produced conflicting results. One study4 found a 21% increase in
mortality rate in those drinking more than 28 cups of coffee a week. However
recent data from a meta-analysis and systematic review5 assessed 23 studies and
concluded that coffee consumption is, in fact, inversely related to the risk of
mortality.
References
1 Rebello S.A.
& van Dam R.M. (2013) Coffee Consumption and Cardiovascular Health: Getting
to the Heart of the Matter. Current Cardiology Reports, 15:403.
2 Kokubo Y. et
al. (2013) The Impact of Green Tea and Coffee Consumption on the Reduced Risk
of Stroke Incidence in Japanese Population: The Japan Public Health Center-Based
Study Cohort. Stroke, published online ahead of print.
3 Correa T.A.F.
et al. (2013) Paper filtered coffee increases cholesterol and inflammation
biomarkers independent of roasting degree. Nutrition, 29(7-8):977-81.
4 Liu J. et al.
(2013) Association of coffee consumtpion with all-cause and cardiovascular
disease mortality. Mayo Clinic Proceedings, published online ahead of print.
5 Malerba S. et
al. (2013) A meta-analysis of prospective studies of coffee consumtpion and
mortality for all causes, cancers and cardiovascular disease. European Journal
of Epidemiology, 28(7):527-539.
Coffee may help perk up your
blood vessels
The caffeine in
a cup of coffee might help your small blood vessels work better, according to
research presented at the American Heart Association's Scientific Sessions
2013.
A study of 27
healthy adults showed – for the first time – that drinking a cup of caffeinated
coffee significantly improved blood flow in a finger, which is a measure of how
well the inner lining of the body's smaller blood vessels work. Specifically,
participants who drank a cup of caffeinated coffee had a 30 percent increase in
blood flow over a 75-minute period compared to those who drank decaffeinated
coffee.
"This gives
us a clue about how coffee may help improve cardiovascular health," said
Masato Tsutsui, M.D., Ph.D., lead researcher and a cardiologist and professor
in the pharmacology department at the University of the Ryukyus in Okinawa,
Japan.
The study adds
to a growing body of research about coffee, the most widely consumed beverage
worldwide. Previous studies showed that drinking coffee is linked to lower
risks of dying from heart disease and stroke, and that high doses of caffeine
may improve the function of larger arteries.
Study participants
were people who did not regularly drink coffee, ranging in age from 22 to 30.
On one day, each participant drank one five-ounce cup of either regular or
decaffeinated coffee. Then researchers measured finger blood flow with laser
Doppler flowmetry, a non-invasive technique for gauging blood circulation on a
microscopic level. Two days later, the experiment was repeated with the other
type of coffee. Neither the researchers nor the participants knew when they
were drinking caffeinated coffee.
The researchers
noted blood pressure, heart rate, and vascular resistance levels. They also
took blood samples to analyze levels of caffeine and to rule out the role of
hormones on blood vessel function.
Compared to
decaf, caffeinated coffee slightly raised participants' blood pressure and
improved vessel inner lining function. Heart rate levels were the same between
the two groups.
Moderate coffee consumption
offers protection against heart failure
While current
American Heart Association heart failure prevention guidelines warn against
habitual coffee consumption, some studies propose a protective benefit, and
still others find no association at all. Amidst this conflicting information,
research from Beth Israel Deaconess Medical Center attempts to shift the
conversation from a definitive yes or no, to a question of how much.
"Our
results did show a possible benefit, but like with so many other things we
consume, it really depends on how much coffee you drink," says lead author
Elizabeth Mostofsky, MPH, ScD, a post-doctoral fellow in the cardiovascular
epidemiological unit at BIDMC. "And compared with no consumption, the
strongest protection we observed was at about four European, or two eight-ounce
American, servings of coffee per day."
The study
published in the journal Circulation:
Heart Failure, found that these moderate coffee drinkers were at 11 percent
lower risk of heart failure.
Data was
analyzed from five previous studies – four conducted in Sweden, one in Finland
– that examined the association between coffee consumption and heart failure.
The self-reported data came from 140,220 participants and involved 6,522 heart
failure events.
In a summary of
the published literature, the authors found a "statistically significant
J-shaped relationship" between habitual coffee consumption and heart
failure, where protective benefits begin to increase with consumption maxing
out at two eight-ounce American servings a day. Protection slowly decreases the
more coffee is consumed until at five cups, there is no benefit and at more
than five cups a day, there may be potential for harm.
It's unclear why
moderate coffee consumption provides protection from heart failure, but the
researchers say part of the answer may lie in the intersection between regular
coffee drinking and two of the strongest risk factors for heart failure –
diabetes and elevated blood pressure.
"There is a
good deal of research showing that drinking coffee lowers the risk for type 2
diabetes, says senior author Murray Mittleman, MD, DrPH, a physician in the
Cardiovascular Institute at Beth Israel Deaconess Medical Center, an Associate
Professor of Medicine at Harvard Medical School and director of BIDMC's
cardiovascular epidemiological research program. "It stands to reason that
if you lower the risk of diabetes, you also lower the risk of heart
failure."
There may also
be a blood pressure benefit. Studies have consistently shown that light coffee
and caffeine consumption are known to raise blood pressure. "But at that
moderate range of consumption, people tend to develop a tolerance where
drinking coffee does not pose a risk and may even be protective against
elevated blood pressure," says Mittleman.
This study was
not able to assess the strength of the coffee, nor did it look at caffeinated versus
non-caffeinated coffee.
"There is
clearly more research to be done," says Mostofsky. "But in the short
run, this data may warrant a change to the guidelines to reflect that coffee
consumption, in moderation, may provide some protection from heart failure."
Coffee = Reduced Risk of Heart
Rhythm Disturbances
Coffee drinkers
may be less likely to be hospitalized for heart rhythm disturbances, according
to a study by the Kaiser Permanente Division of Research in Oakland, Calif. The
researchers note that the findings may be surprising because patients
frequently report palpitations after drinking coffee.
While it has
been established that very large doses of caffeine, the most active ingredient
in coffee, can produce rhythm disturbances, there has been limited
epidemiologic research about the caffeine doses people take. Previous data from
a population study in Denmark compared heavy to light coffee drinkers with
respect to risk of atrial fibrillation, the most common major rhythm
disturbance, and found no statistically significant difference. This research
presentation is believed to be the first large, multiethnic population study to
look at all major types of heart rhythm disturbance, the researchers said.
The researchers
followed 130,054 men and women and found that those who reported drinking four
or more cups of coffee each day had an 18 percent lower risk of hospitalization
for heart rhythm disturbances. Those who reported drinking one to three cups
each day had a 7 percent reduction in risk, according to Arthur Klatsky, MD,
the study's lead investigator and a senior consultant in cardiology at Kaiser
Permanente Division of Research in Oakland, Calif.
"Coffee
drinking is related to lower risk of hospitalization for rhythm problems, but
the association does not prove cause and effect, or that coffee has a
protective effect," Klasky said. Other explanations for the association
might include other traits of coffee drinkers such as exercise or dietary
habits. Additionally, some people with heart rhythm problems often are not
hospitalized.
"However,
these data might be reassuring to people who drink moderate amounts of coffee
that their habit is not likely to cause a major rhythm disturbance,"
Klatsky said. While this report is not sufficient evidence to say that people
should drink coffee to prevent rhythm problems, it supports the idea that
people who are at risk for rhythm problems, or who have rhythm problems, do not
necessarily need to abstain from coffee, emphasized Klatsky.
The long-term
observational study involved 130,054 men and women, 18 to 90 years old, with
the majority less than 50 years old. About 2 percent (3,317) were hospitalized
for rhythm disturbances; 50 percent of those were for atrial fibrillation, the
most common heart rhythm problem. The 18 percent reduction in risk was
consistent among men and women, different ethnic groups, smokers and
nonsmokers. It also was similar for various rhythm problems such as paroxysmal
supraventricular tachycardia, atrial flutter, and atrial fibrillation.
Fourteen percent
of the people in the study drank less than one cup of coffee a day; 42 percent
drank one to three cups of coffee a day; and 17 percent reported drinking four
cups or more each day. Only 27 percent of the people in the study were not coffee
drinkers.
While
emphasizing that these observational data do not establish causality and a
protective mechanism is unclear, researchers speculate that moderate doses of
caffeine may affect rhythm disturbances by antagonism of adenosine, a
nucleoside compound widely distributed in the body. In the heart adenosine has
several effects on conduction of electrical impulses, muscle cell energetics,
and heart muscle cell recovery that might predispose to rhythm problems.
Caffeine antagonizes adenosine effects by blocking its chemical sites of
action.
The researchers
examined hospitalization data by elapsed time after the initial examination.
For hospitalization within 10 years, the reduction in hospitalizations for
people who consumed four cups of coffee or more each day reached 28 percent.
The researchers
also studied persons in the group with or without symptoms or history of heart
and respiratory disease. For both groups, consuming four cups of coffee daily
appeared to be associated with fewer hospitalizations for rhythm disturbances.
Caffeine may prevent heart
disease death in elderly
Habitual intake
of caffeinated beverages provides protection against heart disease mortality in
the elderly, say researchers at SUNY Downstate Medical Center and Brooklyn
College.
Using data from
the first federal National Health and Nutrition Examination Survey
Epidemiologic Follow-up Study, the researchers found that survey participants
65 or more years old with higher caffeinated beverage intake exhibited lower
relative risk of coronary vascular disease and heart mortality than did
participants with lower caffeinated beverage intake.
John Kassotis,
MD, associate professor of medicine at SUNY Downstate, said, "The
protection against death from heart disease in the elderly afforded by caffeine
is likely due to caffeine's enhancement of blood pressure."_
The protective
effect also was found to be dose-responsive: the higher the caffeine intake the
stronger the protection. The protective effect was found only in participants
who were not severely hypertensive. No significant protective effect was in
patients below the age of 65.
Green tea, coffee
may help lower stroke risk
Green tea and
coffee may help lower your risk of having a stroke, especially when both are a
regular part of your diet, according to research published in Stroke: Journal of the American Heart
Association.
"This is
the first large-scale study to examine the combined effects of both green tea
and coffee on stroke risks," said Yoshihiro Kokubo, M.D., Ph.D., F.A.H.A.,
F.A.C.C., F.E.S.C., lead author of the study at Japan's National Cerebral and
Cardiovascular Center. "You may make a small but positive lifestyle change
to help lower the risk of stroke by adding daily green tea to your diet."
Researchers asked
83,269 Japanese adults about their green tea and coffee drinking habits,
following them for an average 13 years. They found that the more green tea or
coffee people drink, the lower their stroke risks.
- People who
drank at least one cup of coffee daily had about a 20 percent lower risk of
stroke compared to those who rarely drank it.
- People who
drank two to three cups of green tea daily had a 14 percent lower risk of
stroke and those who had at least four cups had a 20 percent lower risk,
compared to those who rarely drank it.
- People who
drank at least one cup of coffee or two cups of green tea daily had a 32
percent lower risk of intracerebral hemorrhage, compared to those who rarely
drank either beverage. (Intracerebral hemorrhage happens when a blood vessel
bursts and bleeds inside the brain. About 13 percent of strokes are
hemorrhagic.)
- Participants
in the study were 45 to 74 years old, almost evenly divided in gender, and were
free from cancer and cardiovascular disease.
During the
13-years of follow-up, researchers reviewed participants' hospital medical
records and death certificates, collecting data about heart disease, strokes
and causes of death. They adjusted their findings to account for age, sex and
lifestyle factors like smoking, alcohol, weight, diet and exercise.
Previous limited
research has shown green tea's link to lower death risks from heart disease,
but has only touched on its association with lower stroke risks. Other studies
have shown inconsistent connections between coffee and stroke risks.
Initial study
results showed that drinking more than two cups of coffee daily was linked to
increasing coronary heart disease rates in age- and sex-adjusted analysis. But
researchers didn't find the association after factoring in the effects of
cigarette smoking — underscoring smoking's negative health impact on heart and
stroke health.
A typical cup of
coffee or tea in Japan was approximately six ounces. "However, our
self-reported data may be reasonably accurate, because nationwide annual health
screenings produced similar results, and our validation study showed relatively
high validity." Kokubo said. "The regular action of drinking tea,
coffee, largely benefits cardiovascular health because it partly keeps blood
clots from forming." Tea and coffee are the most popular drinks in the
world after water, suggesting that these results may apply in America and other
countries.
No comments:
Post a Comment