Varieties
There are hundreds of different coffee species, the two most common
being robusta and arabica. Robusta is a hardier plant that grows at lower altitudes and
produces beans with a harsher flavor and higher caffeine content. The arabica plant grows at
high altitudes (3,000 to 6,500 feet or approximately 914 to 1,828 meters) and produces beans
with a smoother, more elegant flavor and slightly less
caffeine.
Roasting times greatly affect the color and flavor of coffee—the longer the beans are
roasted, the stronger the flavor. Among the most popular roasts are American, French, Italian,
European, and Viennese. American roast or regular roast beans are medium-roasted for a
moderate brew. French roast and dark French roast are heavily roasted, yielding deep chocolate
brown beans and producing a stronger coffee. Italian roast are heavily roasted, glossy,
brown-black beans that are strongly flavored and used for espresso. European roast contains
two-thirds heavy-roast beans blended with one-third regular-roast; Viennese roast reverses
those proportions. Instant coffee is a powdered coffee made by heat-drying freshly brewed
coffee. Freeze-drying coffee removes water content by means of a vacuum, with the coffee
solidly frozen and preserved during the process. Bottled coffee drinks are also available,
with milk, sugar, and other sweeteners and flavors.
No matter the variety, all types of coffee contain significant amounts of caffeine, with
the exception, of course, of decaffeinated coffee. Decaffeinated coffee is produced by one of
two methods. Caffeine can be chemically extracted with the use of a solvent, which must be
completely washed out before the beans are dried. Using the Swiss water process, the beans are
steamed, then the caffeine-rich outer layers are scraped away. The solvent method compromises
the flavor of the coffee. The Swiss water process is considered the most desirable method.
Here is the approximate caffeine content of a variety of coffee products. Keep in mind that
the numbers provided are not exact:
-
Brewed (8 oz./250mL) = 85mg of caffeine
-
Instant (8 oz./250mL) = 75mg of caffeine
-
Decaffeinated, brewed (8 oz./250mL) = 3mg of caffeine
-
Decaffeinated, instant (8 oz./250mL) = 3mg of caffeine
-
Espresso (1 oz./30mL) = 40mg of caffeine
-
Cappuccino and Latte (1 oz./30mL) = 40mg of caffeine
Health benefits and concerns
Alcohol
withdrawal
While the support for dietary intervention remains somewhat unclear,
many doctors suggest that alcoholics avoid caffeine. Two
trials have shown that a diet that, among other changes, excludes caffeine, reduces the
craving for alcohol.
Angina
Coffee should probably be avoided. Drinking five cups or more per day
has been shown to increase the risk of angina, although effects of different forms of coffee
on angina are unclear.
Anxiety
All sources of caffeine should be avoided, including coffee, tea, chocolate,
caffeinated sodas, and caffeine-containing medications. People with high levels of anxiety
appear to be more susceptible to the actions of caffeine.
Age-related
cognitive decline
Caffeine may improve cognitive performance. One trial found that
higher levels of coffee consumption were associated with improved cognitive performance, more
so in older people than in younger people. Similar but weaker associations were found for tea consumption.
Atherosclerosis
Blood levels of an amino acid called homocysteine have been linked to atherosclerosis and heart disease. Most studies suggest that
coffee drinkers have higher homocysteine levels than people who do not drink coffee. If coffee
drinking does increase blood levels of homocysteine, the problem might be caused by chemicals
in coffee that are trapped in paper filters. If so, paper-filtered coffee may not have this
deleterious effect. Consumption of coffee made without paper filters will also raise cholesterol levels. Paper-filtered coffee does not have
this effect.
Athletic performance
Caffeine is present in many popular beverages and appears to have an
effect on fat utilization. While most trials show that caffeine does not benefit short-term,
high-intensity exercise, some research has shown that endurance performance is enhanced by
caffeine in many athletes. Caffeine consumption is banned by the International Olympic
Committee at levels that produce urinary concentrations of 12 mg/ml or more. These levels
would require ingestion of considerably more than 2.5mg per pound of body weight, or several
cups of coffee over a short period of time.
Cancer (Bladder)
Most, but not all, published reports have shown coffee drinkers are
at increased risk of bladder cancer. A review of 35 trials found a small (7%) increased risk
of bladder cancer in coffee drinkers compared with people not drinking coffee––a
difference that might have been due to chance.
Cancer (Breast)
Coffee drinking has been reported to increase breast pain associated
with noncancerous lumps in the breast—a condition commonly called fibrocystic breast disease; some researchers believe
some forms of fibrocystic breast disease increase the risk of breast cancer. However, coffee
drinkers are at no higher risk of breast cancer than are women who do not drink coffee. Women
wishing to reduce their risk of breast cancer do not need to avoid drinking coffee.
Cancer (Colon)
Some researchers believe that coffee drinking might reduce the risks
of colon and rectal cancers by decreasing the intestinal level of secondary bile
acids—substances in the gut that may increase the risk of these types of cancer.
However, due to inconsistent support, the association between coffee drinking and protection
against colon or rectal cancers remains unproven.
Cancer (Pancreatic)
While the relationship between coffee drinking and pancreatic cancer
remains unclear, most scientists now believe drinking two cups of coffee per day or less will
not increase the risk of pancreatic cancer.
Cardiac arrhythmia
Some studies have shown a connection between caffeine and cardiac
arrhythmia. Although this effect is thought to be unlikely at moderate amounts, some healthy
people appear to be susceptible to as little as one cup of coffee.
Depression
Consumption of caffeine (mostly from coffee) has paradoxically been
linked with both improvement in mood and depression by different researchers. People with
depression may want to avoid caffeine as well as sugar for one week to see how it affects
their mood.
Diarrhea
Drinking several cups of coffee per day causes diarrhea in some
people. People with chronic diarrhea who drink coffee should avoid all coffee for a few days
to evaluate whether coffee is the culprit.
Eczema
It has been reported that when heavy coffee drinkers with eczema
avoided coffee, eczema symptoms improved. In this study, the reaction was to coffee, not
caffeine, indicating that some people with eczema may be allergic to coffee. People with
eczema who are using a hypoallergenic diet to
investigate food allergies should avoid coffee as part of this trial.
Endometriosis
While some research suggests that women who consume more than 5 grams
of caffeine per month (about 1.5 cups of coffee a day) are
more likely to have endometriosis, no study has investigated whether avoiding caffeine
improves the symptoms of endometriosis.
Fibrocystic breast disease
Long-term and complete avoidance of caffeine reduces symptoms of what
is commonly called fibrocystic breast disease. The decrease in breast tenderness can take six
months or more to occur after caffeine is eliminated. Breast lumpiness has been reported to
not respond well to avoidance of caffeine, but the pain decreases significantly in some
women.
Gallstones
Caffeine increases bile flow and therefore might reduce the risk of
gallstones––an effect supported by a study showing that coffee drinkers have a
lower risk of gallstones than people who do not drink coffee. As caffeinated coffee can
exacerbate symptoms of insomnia, peptic ulcer, panic attacks, and a variety of other
conditions, people at risk for gallstones who wish to consider increasing coffee drinking to
reduce risks should talk with a doctor beforehand.
Gastritis
Both regular and decaffeinated coffee increase stomach acid. Avoiding
these substances should therefore aid in the healing of gastritis.
Gastroesophageal reflux disease (GERD)
Coffee drinking has been linked to increased heartburn pain.
Heart attack
Some but not all studies report that coffee drinking is associated
with an increased risk of suffering a heart attack. This association may result from the
ability of coffee to increase blood levels of
homocysteine, or in the case of unfiltered coffee, to increase blood levels of cholesterol.
High cholesterol
Drinking boiled or French press coffee increases cholesterol levels.
Modern paper coffee filters trap the chemicals in coffee that elevate cholesterol levels,
keeping them from entering the cup. Therefore, drinking paper-filtered coffee generally does
not increase cholesterol levels. However, paper-filtered coffee has been reported to
significantly increase homocysteine—another risk factor for heart disease. The effects
of decaffeinated coffee on cholesterol levels remain in debate.
High homocysteine
Coffee consumption has been associated with increased homocysteine
levels, a risk factor for heart disease.
These findings are consistent with studies that have found caffeine consumption to be
associated with an increased risk of cardiovascular disease
High triglycerides
In a study of heavy caffeine users (people who were consuming an
average of 560mg of caffeine per day from coffee and tea),
changing to decaffeinated coffee and eliminating all other caffeinated products for two weeks
resulted in a 25% reduction in triglyceride levels, a risk factor for heart disease.
Hypertension
Right after consuming caffeine from coffee or tea, blood pressure
increases briefly. While the effects of long-term avoidance of caffeine (from coffee, tea, chocolate, cola
drinks, and some medications) on blood pressure remain unclear, many doctors tell people
with high blood pressure to avoid caffeine.
Hypoglycemia
Even modest amounts of caffeine have been reported to increase
symptoms of hypoglycemia. For this reason, people with low blood sugar should avoid
caffeinated beverages, including coffee.
Female infertility
Some but not all studies find that caffeine reduces female fertility.
Many doctors recommend that women trying to get pregnant avoid caffeine.
Insomnia
The effects of caffeine—a stimulant—can last up to 20
hours, so some people will have disturbed sleep patterns even when their last cup of coffee
was in the morning.
Iron-deficiency anemia
Coffee interferes with the absorption of
iron. However, moderate intake of coffee (4 cups per day) may not increase the risk of
iron-deficiency anemia if the diet contains adequate amounts of iron and vitamin C.
Kidney stones
While many doctors are concerned about the possible negative effects
of caffeine consumption in people with a history of kidney stones, most current research
suggests that it is not important for kidney stone formers to avoid coffee or tea. Preliminary
studies in both men and women have found that coffee and tea consumption is actually
associated with a reduced risk of forming a kidney stone. These reports suggest that
the helpful effect of consuming more water by drinking coffee or tea may compensate for the
theoretically harmful effect that caffeine has in elevating urinary calcium.
Osteoporosis
Caffeine increases urinary loss of calcium. Caffeine intake has been
linked to increased risk of hip fractures and to a lower bone mass in women who consumed
inadequate calcium. Many doctors recommend decreasing caffeinated coffee, black tea, and
caffeine-containing soft drinks as a way to improve bone mass.
Parkinson’s disease
Some but not all research has found that higher coffee and caffeine
intake is associated with a significantly lower incidence of Parkinson’s disease in
older people. Until more is known, increasing caffeine consumption, even in people with a
history of Parkinson’s disease in the family, is not recommended by doctors.
Peptic ulcer
Coffee (including decaf) can aggravate or interfere with the healing
of peptic ulcers. People with peptic ulcer should avoid use of coffee—even decaf.
Pregnancy
Some but not all research links excessive caffeine consumption during
pregnancy to growth-retardation, low birth weight, and spontaneous abortion. The United States
Food and Drug Administration recommends that pregnant women should limit their caffeine intake
to less than 400mg per day––the equivalent of less than four cups of coffee per
day. Although some doctors suggest much lower levels of coffee consumption, no consensus has
been reached on how much coffee drinking is safe for pregnant women.
Premenstrual
syndrome
Among a group of college students in the United States, consumption
of caffeine-containing beverages was associated with increases in both the prevalence and
severity of PMS. Moreover, the more caffeine women consumed, the more likely they were to
suffer from PMS. A preliminary study showed that women with heavy caffeine consumption were
more likely to have shorter menstrual periods and shorter cycle length compared with women who
did not consume caffeine. Therefore, many doctors recommend that women with PMS avoid
caffeine.
Rheumatoid arthritis
Drinking four or more cups of coffee per day has been associated with
an increased risk of developing rheumatoid arthritis (specifically, the form that has a
positive laboratory test for “rheumatoid factor”). Whether avoidance of coffee
would reduce symptoms in people diagnosed with rheumatoid arthritis has yet to be
investigated.