Coffee drinkers who suffer from asthma can breathe a sigh of relief: according to a study performed by a Harvard physician, asthmatic coffee drinkers suffer nearly one-third fewer symptoms of asthma than those who live without java.

Dr. Scott T. Weiss, associate professor of medicine at the Medical School and associate physician at Brigham and Women's Hospital, concluded from a study of more than 20,000 patients that caffeine might serve to relax the constricted lung tissues which cause asthma.

In asthma patients, the muscles surrounding the bronchial passages constrict, blocking the passage of air and making breathing difficult. Senior Environmental Protection Agency scientist Joel D. Schwarz, who collaborated with Weiss on the study, explained that the caffeine, a bronchodilator, is effective against such constriction because it relaxes these muscles.

According to Schwarz, the researchers chose to study coffee because caffeine is chemically similar to theophylline, an asthma treatment. So far, coffee is the only beverage found to produce these results.

"We were unable to demonstrate any effect in tea or colas," Weiss said, adding that such beverages contain significantly less caffeine than coffee.

Weiss stressed that while caffeine can relieve some background symptoms of asthma, coffee is not a substitute for appropriate therapy for asthma.

"If you took away coffee, more symptoms would be reported," said Weiss. "If you've got asthma, see a doctor and get the right medicine."

Dr. Dirk K. Greineder, who is an assistant clinical professor of medicine at the Medical School and treats asthma patients, described the study's results as "a real link."

"I'm not surprised by the findings," Greineder said. "One would have predicted that caffeine helps asthma."

"Until recently, the mainstay medication for asthma was theophylline, which is chemically very similar to caffeine," Greineder said. "I've had patients with high caffeine intakes who needed to take less theophylline to adjust for the caffeine."

Approximately eight million adult Americans suffer from asthma, with treatment costs of up to $4.6 billion a year, according to the study.

Asthma is the leading cause of absence from school, amounting to ten million lost school days per year.