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Caffeine
Caffeine
Caffeine: A User's Guide
Caffeine and Your Health Caffeine is one of the best-researched substances in the food
supply. The overwhelming scientific evidence suggests that, in moderation, it has no adverse health
effects. According to the International Food Information Council, moderation means 1 to 2 mugs (10
to 20 ounces) of brewed coffee per day, or 3 to 6 12-ounce glasses of iced tea (table 1: not shown).
While little harm can be directly associated with coffee or other caffeinated beverages, coffee drinkers
do tend to do things that contribute to health risks. Surveys suggest that they are more likely to smoke
cigarettes, exercise too little, and eat fatty meats. Tea drinkers, in comparison, tend to exercise more
and eat more fresh fruit. For women, caffeine has been suspected as a factor in fibrocystic breast
disease. But no research supports the connection, and the American Medical Association has stated
that there is no association between caffeine intake and fibrocystic breast disease, benign tumors,
breast tenderness, or breast cancer--or cancer of any type. Also, caffeine is not an important risk
factor for osteoporosis in women who drink at least one glass of milk per day. But when caffeinated
beverages replace milk, low calcium intakes may interfere with bone health. A woman who wants to
start a family should be aware that consuming over 300 milligrams of caffeine a day might increase the
time it takes to get pregnant, as well as the risk of miscarriage or a low-birth-weight baby. The US
Food and Drug Administration recommends that pregnant women avoid caffeine-containing foods and
drugs or consume them only sparingly, because caffeine crosses the placenta and is a stimulant to the
unborn baby. It is also transferred into breast milk, so women who breastfeed should avoid caffeine.
If you are prone to anemia, note that polyphenols in coffee and tea can interfere with iron absorption.
Your best bet is to drink caffeinated beverages an hour before a meal, rather than afterward. Some
people become dependent on caffeine, experiencing withdrawal symptoms such as headaches, fatigue,
or drowsiness if they abstain. These effects last only a few days and can be avoided by gradually
reducing caffeine intake instead of quitting "cold turkey."
Energy-Enhancing Properties Because caffeine enhances performance in many individuals,
it has been banned by the International Olympic Committee. But ironically, the level at which caffeine
is banned far exceeds the amount needed to enhance performance. Higher, illegal levels are generally
attained with caffeine supplements, since a 150-pound athlete would need to drink 3 to 4 large cups
of coffee within an hour before activity to reach the upper acceptable limit. Just 1.5 to 3 milligrams of
caffeine per pound of body weight (225 to 450 milligrams for a 150-pound man) is enough for an
energy-enhancing effect. That's as little as one 10-ounce cup of coffee! Habitual caffeine consumers
experience less ergogenic effect than people who consume it rarely. For the optimal ergogenic benefit,
the trick may be to use caffeine strategically at certain points to allow for harder training, and then
discontinue it to avoid developing a tolerance. Caffeine affects each person's performance differently.
Some athletes thrive on it; others prefer to abstain because it causes stomach upset, nervousness, or
jitters. Clearly, if caffeine makes you queasy or lightheaded during exercise, don't use it!
Caffeine and Hydration Caffeine also has a diuretic effect--that is, it enhances urine formation, often
causing a need to urinate within an hour after consumption. Yet two studies with subjects who took
caffeine before they exercised (1,2) showed no detrimental effects on hydration during exercise. Thus
it appears that caffeine does not increase urine production during exercise. The extra adrenaline your
body secretes during exercise may block caffeine's effect on the kidneys (3). However, responses to
caffeine vary, so you should base your preexercise consumption on how caffeine affects your body.
After exercise, caffeine is a poor choice for fluid replacement. The safest bet is to tank up on
noncaffeineated beverages just after activity, and then later, if you so desire, enjoy your favorite
caffeinated beverage in moderation.
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The above information is not intended as a substitute for appropriate medical treatment.
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