February 1/London/Daily Mail -- Drinking coffee improves women's brainpower in stressful situations but sends men into meltdown, according to a study.

While sipping a cappuccino or downing an espresso boosts women's performance when working with others, the same drinks impair men's memories and slow their decision-making. Given that Britons get through some 70 million cups of coffee a day, the implications are significant, say the researchers.

Psychologist Dr. Lindsay St Claire said, "Many meetings, including those at which military and other decisions are made, are likely to be male-dominated.

"Because caffeine is the most widely consumed drug in the world, the global implications are potentially staggering."

The researchers, from Bristol University, wanted to examine what coffee does to the body when it is already under stress, such as during a tense meeting.

They recruited 64 men and women and put them in same-sex pairs. Each pair was given a range of tasks to complete, including carrying out negotiations, completing puzzles and tackling memory challenges, and told they would have to give a public presentation relating to their tasks afterward.

Half of the pairs were given decaffeinated coffee, while the others were handed a cup containing a large shot of caffeine.

The researchers found that men's performance in memory tests was "greatly impaired" if they drank the caffeinated coffee. They also took an average of 20 seconds longer to complete the puzzles than those on the decaffeinated coffee.

However, women completed the puzzles 100 seconds faster if they had been given caffeine, the Journal of Applied Social Psychology reports.

Previous studies have suggested that coffee may provide protection against diabetes, Alzheimer's disease, liver damage and gout.

From the February 7, 2011, Prepared Foods E-dition