| Risks
Cancer
Over 1,000 chemicals have been reported in roasted coffee: more than
half of those tested (19/28) are rodent carcinogens.
Gastrointestinal problems
Coffee can damage the lining of the gastrointestinal organs, causing
gastritis and ulcers. It is recommended for people with gastritis,
colitis, and ulcers to stop consuming coffee.
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.
Cosmetic
Like tea, coffee causes staining of the teeth.
Cholesterol
A 2007 study by the Baylor College of Medicine indicates that the
diterpene molecules cafestol and kahweol, found only in coffee beans,
putatively 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 serves to link cafestol and kahweol with
higher levels of cholesterol in the body.
Paper coffee filters have a property that binds to lipid-like compounds
which allows it 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, fail to remove any cafestol and kahweol from the final
brewed product. In contrast, drip brewing with a paper filter removes
most of the cafestol and kahweol from the coffee.
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 and menopause
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.
There are also gender-specific effects: in some PMS sufferers it
increases the symptoms; it can reduce fertility in women; it may
increase the risk of osteoporosis in postmenopausal women.
Decaffeinated coffee is also regarded as a potential health risk to
pregnant women due to the high incidence of chemical solvents used to
extract the caffeine. 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.[38] 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.
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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