People who eat lots of soy products have better lung function and are less likely to develop the smoking-associated lung disease COPD (Chronic Obstructive Pulmonary Disease). A study published in BioMed Central's open access journal Respiratory Research has shown that consumption of a wide variety of soy products can be associated with a reduction in the risk of COPD and other respiratory symptoms.

Dr. Fumi Hirayama and Professor Andy Lee from Curtin University of Technology, Australia, worked with a team of respiratory physicians to poll 300 patients with COPD from six Japanese hospitals and 340 age-matched control subjects from the same areas as the patients about their soy intake. Dr. Hirayama said, "Soy consumption was found to be positively correlated with lung function and inversely associated with the risk of COPD. It has been suggested that flavonoids from soy foods act as an anti-inflammatory agent in the lung, and can protect against tobacco carcinogens for smokers. However, further research is needed to understand the underlying biological mechanism".

Soy is a constituent of many Japanese foods, including tofu (soybean curd), natto (fermented soybeans), miso soup (fermented soybean paste), bean sprouts and soy milk. It has been claimed that soy foods reduce cholesterol and can alleviate menopause symptoms. This is the first study to demonstrate the association between consumption of the superfood and a reduction in the risk of developing COPD.

COPD is characterized by progressive decline in lung function, and encompasses chronic bronchitis and emphysema. Long-term cigarette smoking causes almost 90% of COPD. This research only shows an association between soy intake and a reduced risk of developing the condition; the best preventive measure is still to abstain from tobacco entirely.