Eating high amounts of soy could lower the risk of the breathing disorder known as chronic obstructive pulmonary disease, or COPD, researchers report.

Cigarette smoking is known to be the principle risk factor for COPD, Dr. Andy H. Lee of the Curtin University of Technology, Perth, Australia, and colleagues point out in their report in the journal Respiratory Research. "Other factors such as dietary and environmental exposures may protect against, or contribute to, disease development."

The investigators studied 278 COPD patients (244 men and 34 women) between the ages of 50 and 75 years who were diagnosed within the past 4 years. They also recruited 340 people (272 men and 68 women) without the disease.

Control subjects consumed more soy per day (about 60 grams) than patients with COPD (about 45 grams). The risk of COPD was significantly reduced among those who ate more soy.

Similar decreases in the risk of COPD were observed with higher intakes of tofu and bean sprouts. The more soy people consumed, the fewer breathing problems they had, particularly breathlessness.

"Habitual intake of soy foods ... can have an important impact on the cost to health care systems associated with the morbidity and death from this disease," Dr. Lee told Reuters Health. "Long-term follow-up studies are recommended to ascertain whether soy consumption can lengthen the survival of patients already diagnosed with COPD."