Java Gives Caffeine-naive A Boost, Too

"The take-home message for women is that whether you are hooked on caffeine or not, if you need a boost coffee improves your mental alertness and can have a calming affect on your heart rate," said Michael Kennedy, a professor in exercise physiology in the University of Alberta's Faculty of Physical Education and Recreation, lead author on the study. "In addition, a large coffee has more than enough caffeine to see these changes."

Kennedy and a team of students looked at how 10 women who drank caffeine daily and 10 caffeine-naïve women who drank less than two servings per week were affected by measuring heart rate, blood pressure, alertness and the ability to perform a tough mental test after consuming a 350-millilitre-sized coffee. The study subjects were aged 18 to 37.

After eating a normal breakfast, participants were asked to drink a cup of regular coffee containing approximately 140 milligrams of caffeine. After allowing 50 minutes for the absorption of the caffeine, participants in both groups were required to complete two word tasks. Heart rate, blood pressure and alertness were monitored before and after the test.

Of some concern, noted Kennedy, is that baseline blood pressure taken before the groups digested the caffeine was significantly higher in the habituated coffee drinkers. "This indicates that there may be some long-term cardiovascular adjustment to digesting caffeine on a daily basis," said Kennedy, adding that though the sample was small, the results were statistically and clinically significant.

"For people at risk for high blood pressure, if you're a habituated coffee drinker, reducing your caffeine intake would be an effective way of potentially reducing your blood pressure."