What
is caffeine? Caffeine is a plant product that is
most commonly found in coffee beans, tea, soft drinks, cocoa and
chocolate. Caffeine is also found in some prescription and non-prescription
drugs, including cold, allergy and pain relievers.
How does caffeine
affect the body? Caffeine acts as a stimulant by
exerting a strong effect on the central nervous system. The effects
of caffeine on the body may begin as early as 15 minutes and last
up to six hours.
Caffeine may increase heart rate, body temperature,
blood flow to the skin & extremities, blood pressure,
blood sugar levels, stomach acid secretion and production
of urine (diuretic).
Positive (or no known
negative) effects When caffeine is consumed
in moderate doses (about two
6-oz cups of coffee or about four 12-oz colas), there are no known negative effects. It can decrease drowsiness and increase motor activity. Contrary to popular belief, drinking coffee will not help someone who is intoxicated become sober.
Most individuals consuming moderate amounts (about two
6-oz cups of coffee per day) will experience few, if any, negative
side effects. In general, moderate consumption of caffeine
does not seem to increase one's risk for irregular heartbeats,
heart disease, high cholesterol levels, cancer (including breast
cancer), fibrocystic breast disease or infertility.
Minor side effects Sensitivity
to caffeine varies. Some people can drink several cups of coffee
or other caffeinated beverages with few side effects. Other individuals
may be so sensitive that even a small amount of caffeine makes
them uncomfortable.
If people are especially sensitive to caffeine or if they consume
more than 250 mg at one time (more than two 6-oz cups of coffee
or five 12-oz colas), they may notice minor side effects including
insomnia, restlessness, irritability, nervousness, headaches,
hand tremors, extra heartbeats and an inability to concentrate.
Less noticeable side effects include a temporary
increase in blood pressure, breathing rate and metabolism.
Some symptoms of PMS (breast tenderness, irritability
and headache) may be increased with caffeine use.
Also, some researchers think that caffeine increases
the amount of calcium lost in urine and feces. However,
as long as people get the recommended amount of calcium
each day (1000 mg), the effects of caffeine on the
bones seem to be minimal. For more information on
calcium in the diet and osteoporosis, see Medline
Plus.
More serious side effects While
consuming moderate amounts of caffeine does not seem to have long-term
detrimental effects, consuming larger amounts of caffeine on a
regular basis (1000 mg or about ten 6-oz cups of coffee a day)
may be linked to conception problems, increased episodes of heartburn,
and changes in bowel habits.
Too much caffeine may lead to sleep deprivation and a tendency
to disregard the normal warning signals that the body is tired
and needs rest. Caffeine does not replenish energy or prevent
emotional fatigue; food and sleep are the only remedies for these.
When normal sleeping patterns are continually disrupted, mood
depression may occur. Too much caffeine may also lead to anxiety-related
feelings such as excessive nervousness, sweating and tremors.
People who are taking medications for depression, anxiety or
insomnia, high blood pressure, other heart problems, chronic stomach
upset or kidney disease should avoid caffeine until discussing
the matter with a clinician.
If you want to avoid some of the annoying side effects of caffeinated
beverages (e.g., jitters or sleeplessness), switching to decaffeinated
drinks may help.
Should I avoid
caffeine during pregnancy? Some studies show an
association of high doses of caffeine with an increased rate of
miscarriages, premature deliveries or low birth weights. However,
complicating factors such as smoking and alcohol use were not accounted
for. In high doses, caffeine can affect fetal breathing and heart
rate. If you are pregnant, or planning to become pregnant, you may
want to consider your options such as eliminating caffeine from
your diet or limiting intake to no more than 200-300 mg (2-3 cups
of coffee) per day. This matter should be discussed further with
your clinician.
Is caffeine
addictive? Many people who drink caffeinated beverages
become dependent on caffeine. They crave it in order to feel its
effects. Many feel they need a caffeinated beverage to get going
in the morning.
Some people who drink caffeinated beverages feel that they develop
a tolerance to caffeine, needing more and more caffeine to produce
the same stimulant effects. It is thought that tolerance occurs
because people who drink a lot of caffeinated beverages can metabolize
the caffeine faster and therefore want more sooner.
What side effects can I
expect if I quit? People who stop
drinking caffeinated drinks may notice several side
effects--especially if they are used to consuming large
amounts of caffeine. Some symptoms of caffeine withdrawal
include headaches, constipation, irritability, nervousness,
nausea and muscular tension. These symptoms usually
appear about 12-24 hours after someone has stopped consuming
caffeine and usually last about one week. It is recommended
that you gradually decrease your caffeine intake to
avoid withdrawal symptoms.
What about decaffeinated
beverages? The health side effects of decaffeinated
beverages are just as widely debated as the effects of beverages
containing caffeine. Moderate amounts are unlikely to cause any
negative health effects. However, there are other compounds in some
decaffeinated teas and coffee that could further irritate existing
ulcers and frequency of heartburn.
