By Willow Lawson, published on January 1, 2003 - last reviewed on June 9, 2016
Don't expect the pendulum to stop swinging any time soon when it
comes to the verdict about caffeine.
For years, many of us have been vaguely aware of news reports
associating caffeine with insomnia, osteoporosis, low birth weight,
fertility problems, high blood pressure and changes in metabolism. Over
the past few decades, there's been a flurry of research to determine
whether we should all lay off the world's most popular drug.
But these days, the news you hear is as likely to be good as bad.
Recently, caffeine intake has been associated with increased mental
agility in the elderly. It has been shown repeatedly to boost physical
performance. It fights fatigue and has been implicated in a lower risk of
Parkinson's disease. Recent studies have absolved coffee-drinking of
causing chronic hypertension, although it is known to temporarily raise
And lately, Swedish researchers gave caffeine a pass during
pregnancy, debunking reports that link the chemical with low birth
weight. (The scientists said previous low birth weight pregnancies,
nausea and long work hours were more likely to be associated with the
Perhaps the real news about caffeine is that it can be detrimental
to very specific groups of people.
o A diet high in caffeine has been linked to an increase in Type 2
(adult-onset) diabetes in people who are obese and don't exercise,
according to researchers at the University of Guelph in Canada. The study
found obese people have a low sensitivity to insulin, the hormone that
regulates blood sugar. Some insulin is essential, but too much insulin
causes problems, including weight gain. Caffeine pushes insulin levels
even higher in obese individuals.
o A study at the University of Kansas Medical Center showed that
people with an inherited disease known as ADPKD (autosomal dominant
polycystic kidney disease) -- which causes cysts in kidneys and can lead to
the need for a transplant -- may want to cut short their coffee habit.
Caffeine was found to encourage the growth of cysts, which can grow to
the size of grapefruit and crowd out normal tissue.
o Researchers at the University of Washington found that the
combination of smoking, coffee drinking and high blood pressure can up
the risk of having a rare type of stroke caused by bleeding between the
brain and it's protective membrane. People who smoke quadrupled their
risk for this stroke, scientists found. Ditto for those people who drank
five or more cups of coffee a day.
o A study at the Robert Wood Johnson Medical Center in New Jersey
found that people who control their epilepsy with medication should avoid
caffeine, which has been found to cause seizures in people who have
controlled their epilepsy for years.
What does that mean for the rest of us? Most medical professionals
agree that "moderate" caffeine intake -- a couple cups of coffee a
day -- shouldn't worry the average person. Humans have been using caffeine
to stimulate their bodies for thousands of years in the form of tea,
coffee, chocolate and other natural forms of the drug. It makes us feel
good by increasing the levels of the calming neurotransmitter
So while many of us reach for our cup of joe and tune out the often
conflicting caffeine news reports, it may not be a bad idea to keep