Real Scoop on Coffee and Caffeine
JoAnn E. Manson, MD, DrPH - Harvard Medical School
So you worry that coffee could harm your health? Relax.
Studies suggest that, when consumed in moderation --
meaning two to four eight-ounce servings daily --
coffee may in fact be good for you.
is not clear whether the benefits come from coffee
itself or its caffeine. Even decaffeinated coffee may
have some caffeine, and there is limited research on
other caffeinated beverages, such as tea. Per cup,
coffee has about 100 mg of caffeine... black tea has
about half as much. Studies show that coffee may...
Reduce risk for some cancers. An
analysis of nine studies found that drinking two cups of
coffee daily lowered liver cancer risk by 43%. Coffee
also may protect against colorectal cancer.
Help prevent diabetes. Among 200,000
study participants, those who drank four to six cups of
regular or decaffeinated coffee daily were 28% less
likely to develop type 2 diabetes than people who drank
two cups or less daily.
Chlorogenic acid, an antioxidant in coffee, slows
sugar’s release into the bloodstream.
Protect memory. In a study of 7,000
seniors, women who drank more than three cups of
caffeinated coffee or six cups of caffeinated tea daily
had less memory loss than women who drank two cups or
Prevent gallstones. In a study of
80,000 female nurses, drinking two or more cups of
caffeinated coffee daily cut gallstone risk by about
Why: Caffeine may aid the
digestive fluid bile, reducing formation of cholesterol
crystals that become stones... and stimulate gallbladder
contractions, flushing away crystals.
Lower Parkinson’s disease risk. In the
nurses’ study, women who drank one to three cups of
caffeinated coffee daily were 40% less likely than
nondrinkers to develop Parkinson’s, a movement disorder
caused by loss of brain cells.
Improve physical performance. The
amount of caffeine in two to five cups of coffee boosts
endurance... helps the body burn fat instead of
carbohydrates... and eases muscle soreness.
Reassuring: Coffee drinkers
are no more likely to have heart attacks or chronic high
blood pressure than nondrinkers. Coffee oils can raise
cholesterol, but paper filters remove these oils. Coffee
doesn’t appear to increase risk for ovarian or breast
cancer. Some women say coffee worsens premenstrual
syndrome and fibrocystic breast disease (benign breast
lumps), but research does not support this.
Cautions: Both regular and
decaf coffee can cause digestive upset. Caffeine can
trigger migraine or cause insomnia. Animal studies
suggest that at high doses, caffeine may weaken bones by
blocking calcium absorption. Moderate amounts of
caffeine do not impair fertility or cause birth defects,
but consuming more than 200 mg daily may double
miscarriage risk -- so limit caffeine to 100 mg per day