Health Effects Of Coffee
The
health effects of coffee
have been studied to determine how coffee drinking affects humans. Coffee
contains
several compounds which are known to affect human body chemistry. The
coffee
bean itself contains chemicals which are mild psychotropics
for humans as a defense mechanism of the Coffeacute
plant. These chemicals are toxic in large doses, or even in their normal
amount
when consumed by many creatures which may otherwise have threatened the
beans
in the wild. Coffee contains caffeine,
which acts as a stimulant.
Recent
research has uncovered
additional stimulating effects of coffee which are not related to its
caffeine
content. Coffee contains a currently unknown chemical agent which
stimulates
the production of cortisone and adrenaline,
two stimulating hormones. For occasions when
one wants to enjoy the flavor of coffee with almost no
stimulation, decaffeinated coffee (also called
decaf)
is available. This is coffee from which most of the caffeine has been
removed,
by the Swiss
water process (which involves the
soaking of raw beans to remove the caffeine) or the use of a chemical solvent
such as trichloroethylene ("tri"), or
the more popular methylene
chloride, in a similar process.
Another solvent used is ethyl acetate;
the resultant decaffeinated
coffee is marketed as "natural decaf" because ethyl acetate is
naturally present in fruit. Extraction with supercritical carbon
dioxide has also been employed.
Decaffeinated
coffee usually
loses some flavor compared to normal coffee. There are also coffee
alternatives
that resemble coffee in taste but contain no caffeine (see below). These
are
available both in ground form for brewing and in instant form. Caffeine
dependency and withdrawal
symptoms are well-documented
Benefits Of Coffee
Reduced risk of Alzheimer's disease and Dementia
Several
studies comparing moderate coffee drinkers (defined as 3–5 cups per day) with
light coffee drinkers (defined as 0–2 cups per day) found that those who drank
more coffee were significantly less likely to develop Alzheimer's disease later in life. A
longitudinal study in 2009 found that moderate coffee drinkers had reduced risk
of developing dementia
in addition to Alzheimer's disease.
Reduced risk of gallstone disease
Drinking
caffeinated coffee has been correlated with a lower incidence of gallstones
and gallbladder
disease in both men and women in two studies
performed by the Harvard School of Public Health.
A lessened risk was not seen in those who drank decaffeinated coffee. A recent
study showed that roast coffee protected primary neuronal cells against
hydrogen peroxide-induced cell death.
Reduced risk of Parkinson's disease
A study
comparing heavy coffee drinkers (3.5 cups a day) with non-drinkers found that
the coffee drinkers were significantly less likely to develop Parkinson's disease later in life. Likewise, a second study found an inverse relationship
between the amount of coffee regularly drank and the likelihood of developing
Parkinson's disease.
Cognitive performance
Many people
drink coffee for its ability to increase short term recall.
Likewise, in tests of simple reaction
time, choice reaction time, incidental verbal memory, and visuospatial
reasoning, participants who regularly drank coffee were found to perform better
on all tests, with a positive relationship between test scores and the amount
of coffee regularly drunk. Elderly participants were found to have the largest
effect associated with regular coffee drinking. Another
study found that women over the age of 80 performed significantly better on
cognitive tests if they had regularly drunk coffee over their lifetimes.
Analgesic enhancement
Coffee
contains caffeine, which increases the effectiveness of pain killers,
especially migraine
and headache medications.
For this reason, many over-the-counter
headache drugs include caffeine in their formula.
Antidiabetic
Coffee intake
may reduce one's risk of diabetes mellitus type 2 by up to half. While
this was originally noticed in patients who consumed high amounts (7 cups a
day), the relationship was later shown to be linear.
Liver protection
Coffee can
also reduce the incidence of cirrhosis of the liver
and has been linked to a reduced risk of hepatocellular carcinoma, a primary liver
cancer that usually arises in patients with preexisting cirrhosis The exact
mechanism and the amount of coffee needed to achieve a beneficial effect have
long been unclear. The cytokine transforming growth factor (TGF) beta has long
been recognized for promoting fibrosis ability acting through the Smad family
of transcription factors. In an interesting report recently published in the
Journal of Hepatology, Gressner and colleagues provide the first mechanistic
context for the epidemiological studies on coffee drinkers by showing that
caffeine may have potent anti-fibrotic capabilities through its ability to
antagonize the Smad pathway.
Cancer
Coffee
consumption is also correlated to a reduced risk of oral, esophageal,
and pharyngeal cancer. In ovarian cancer,
no benefit was found. In the Nurses' Health Study, a modest reduction in breast cancer
was observed in postmenopausal women only, which was not confirmed in
decaffeinated coffee, and a reduction in endometrial cancer was observed in people who
drank either caffeinated or decaffeinated coffee. According to one study,
coffee protects the liver from cancer. Another preliminary study found a
correlation between coffee consumption and a lower risk of aggressive prostate cancer.
Cardioprotective
Coffee
moderately reduces the incidence of dying from cardiovascular disease, according to a large
prospective cohort study published in 2008. A 2009 prospective study in Japan following
nearly 77,000 individuals aged 40 to 79 found that coffee consumption, along
with caffeine intake, was associated with a reduced risk of dying from
cardiovascular disease.
Laxative/diuretic
Coffee is also
a powerful stimulant for peristalsis and is sometimes considered to
prevent constipation.
However, coffee can also cause excessively loose bowel movements.
The stimulative effect of coffee consumption on the colon is found in both
caffeinated and decaffeinated coffee.
Practitioners in alternative medicine often recommend coffee enemas for "cleansing
of the colon" due to its stimulus of peristalsis,
although medicine
has not proven any benefits of the practice.
Contrary to popular belief, caffeine
does not act as a diuretic when consumed in moderation, and does
not lead to dehydration or to a water-electrolyte imbalance; current evidence
suggests that caffeinated beverages contribute to the body's daily fluid
requirements no differently from pure water.
Antioxidant
Coffee
contains the anticancer compound methylpyridinium. This
compound is not present in significant amounts in other foods. Methylpyridinium
is not present in raw coffee beans but is formed during the roasting process
from trigonelline,
which is common in raw coffee beans. It is present in both caffeinated and
decaffeinated coffee, and even in instant coffee. Research funded by Kraft
shows that roast coffee contains more lipophilic antioxidants and chlorogenic acid
lactones and is more protective against hydrogen peroxide-induced cell death in
primary neuronal cells than green coffee. The espresso
method of extraction yields higher antioxidant activity than other brewing methods.
Prevention of dental caries
The tannins in coffee may
reduce the cariogenic potential of foods. In vitro experiments have shown that
these polyphenolic compounds may interfere with glucosyltransferase activity of
mutans streptococci, which may reduce plaque
formation.
Gout
Coffee
consumption decreased risk of gout
in men over age 40. In a large study of over 45,000 men over a 12-year period,
the risk for developing gout in men over 40 was inversely proportional with the
amount of coffee consumed.
Cancer
Over 1,000
chemicals have been reported in roasted coffee, and 19 are known rodent carcinogens; however, most substances cited as rodent
carcinogens occur naturally and should not be assumed to be carcinogenic in
humans at exposure levels typically experienced in day-to-day life.
Gastrointestinal problems
Coffee can
damage the lining of the gastrointestinal organs, causing gastritis and ulcers.
The consumption of coffee is therefore not recommended for people with
gastritis, colitis, and ulcers.
Anxiety and sleep changes
Many coffee
drinkers are familiar with "coffee jitters", a nervous condition that
occurs when one has had too much caffeine. It can also cause anxiety
and irritability,
in some with excessive coffee consumption, and some as a withdrawal symptom.
Coffee can also cause insomnia in some. In others it can cause narcolepsy.
Cholesterol
A 2007 study by the Baylor College of Medicine indicates that the diterpene
molecules
cafestol
and kahweol,
found only in coffee beans, may raise levels of low-density lipoprotein or LDL in humans. This
increase in LDL levels is an indicator that coffee raises cholesterol.
The Baylor study suggests a possible link between cafestol, kahweol and higher
levels of cholesterol in the body.
Paper coffee filters have a property
that binds to lipid-like compounds which allows the filter to remove most of
the cafestol and kahweol found in coffee. Brew methods which do not use a paper
filter, such as the use of a press pot, do not remove cafestol and kahweol from
the final brewed product.
Blood pressure
Caffeine has
previously been implicated in increasing the risk of high blood pressure;
however, recent studies have not confirmed any association. In a 12-year study
of 155,000 female nurses, large amounts of coffee did not induce a "risky
rise in blood pressure". Previous studies had
already shown statistically insignificant associations between coffee drinking
and clinical hypertension. Effect of coffee on morbidity and mortality due to
its effect on blood pressure is too weak, and has not been studied. Other
positive and negative effects of coffee on health would be difficult
confounding factors.
Effects on pregnancy
Caffeine
molecules are small enough to penetrate the placenta and slip into the baby's
blood circulation. Unlike adults, organs and systems in fetuses are not
full-fledged, therefore not capable of fully metabolizing caffeine and
excreting it. The energy booster tends to linger in the fetus's blood ten times
longer than in adults. High levels of caffeine are bound to accumulate in the
baby's body with frequent maternal consumption of caffeine. Just like what it
does to adults, caffeine could also send the baby's pulse and breathing rate
racing and affect its sleep pattern for an extended duration.
A February
2003 Danish
study of 18,478 women linked heavy coffee consumption during pregnancy to
significantly increased risk of stillbirths
(but no significantly increased risk of infant death in the first year).
"The results seem to indicate a threshold effect around four to seven cups
per day," the study reported. Those who drank eight or more cups a day (64
U.S. fl oz or 1.89 L) were at 220% increased risk compared with nondrinkers.
This study has not yet been repeated, but has caused some doctors to caution
against excessive coffee consumption during pregnancy.
Decaffeinated
coffee is also regarded as a potential health risk to pregnant women when
chemical solvents are used to extract the caffeine instead of other less
invasive processes. The impact of these chemicals is debated, however, as the
solvents in question evaporate at 80–90 °C, and coffee beans are decaffeinated
before roasting, which occurs at approximately 200 °C. As such, these
chemicals, namely trichloroethane and methylene chloride, are present in trace
amounts at most, and may not pose a significant threat to embryos and fetuses.
Iron deficiency anemia
Coffee
consumption can lead to iron deficiency anemia in mothers and
infants. Coffee also interferes with the absorption of supplemental iron.
Coronary artery disease
A 2004 study
tried to discover why the beneficial and detrimental effects of coffee
conflict. The study concluded that consumption of coffee is associated with
significant elevations in biochemical markers of inflammation.
This is a detrimental effect of coffee on the cardiovascular system, which may explain why
coffee has so far only been shown to help the heart at levels of four cups (24
fl oz or 600 mL) or fewer per day.
The health
risks of decaffeinated coffee have been studied, with varying results. One
variable is the type of decaffeination process used; while some involve the use
of organic solvents which may leave residual
traces, others rely on steam.[citation
needed]
A study has
shown that cafestol,
a substance which is present in boiled coffee drinks, dramatically increases cholesterol
levels, especially in women. Filtered coffee contains only trace amounts of
cafestol. Polymorphisms in the CYP1A2
gene may lead to a slower metabolism of caffeine. In patients with a slow
version of the enzyme the risk for myocardial infarction (heart attack) is
increased by a third (2–3 cups) to two thirds (>4 cups). The risk was more
marked in people under the age of 59.
A Harvard
study conducted over the course of 20 years of 128,000 people published in 2006
concluded that there was no evidence to support the claim that coffee
consumption itself increases the risk of coronary heart disease. The study did, however,
show a correlation between heavy consumption of coffee and higher degrees of
exposure to other coronary heart disease risk factors such as smoking, greater
alcohol consumption, and lack of physical exercise. The
results apply only to coffee filtered through paper filters, which excludes
boiled coffee and espresso, for example. Additionally, the lead researcher on
this study acknowledged that subsets of the larger group may be at risk for
heart attack when drinking multiple cups of coffee a day due to genetic
differences in metabolizing caffeine.
The Iowa
Women's Health Study showed that women who consumed coffee actually had fewer
cardiovascular disease incidents and lower cancer rates than the general
population. For women who drank 6 or more cups, the benefit was even greater.
However, this study excluded 35% of its original participants who already had
cardiovascular disease and other chronic diseases when the study began. Since
participants were all over the age of 55, no good conclusion can be drawn about
the long term effect of coffee drinking on heart disease from this study.

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