Can eating extra edamame or taking a soy supplement improve breathing in patients with poorly controlled asthma? According to a team of researchers from the American Lung Association Asthma Clinical Research Centers (ACRC), including University of Vermont asthma expert Charles Irvin, Ph.D., the answer is no.
The researchers’ findings appear in the May 26, 2015 Journal of the American Medical Association.
Irvin, professor of medicine and associate dean for faculty at the UVM College of Medicine, and ACRC colleagues set out to test a theory that asthma patients could improve their lung function by consuming a soy supplement. The team’s hypothesis was based on the fact that a component of soy – genistein, which is an isoflavone – is known to have anti-inflammatory properties. Early studies in animal models and humans had shown that the isoflavone reduced cell inflammation that exacerbates asthma, Irvin says.
The group’s assumption dated to their 2001 New England Journal of Medicine study, titled “The Safety of Inactivated Influenza Vaccine for Adults and Children with Asthma,” or SIIVA. The SIIVA study involved a lengthy food questionnaire that revealed that patients who ate a lot of soy had better lung function.
“We were really quite impressed with that relationship,” says Irvin, who also serves as director of the Vermont Lung Center and vice chair of research in the Department of Medicine.
In order to confirm the direct effect in asthma patients – specifically adolescents and adults whose asthma wasn’t well-controlled with other treatments – the ACRC researchers conducted a randomized study with 386 patients age 12 and older. Half were prescribed a soy supplement and the other half a placebo, which they took over a six-month period.
To the group’s surprise, there was no difference in the patients’ measured lung function or clinical outcomes.
“It was stone-cold negative,” Irvin says. “There was just no effect that we could find at all. And we looked very hard.”
The study was the latest work of the ACRC, a network of 18 institutions organized and supported by the American Lung Association. UVM joined the network in 1999 as the only center in New England and the only one in a rural setting.
The ACRC group initiates multi-center evaluations of “medication treatment schemes that are novel and are of great interest to patients,” Irvin says. They have embarked on new studies of continuous positive airway pressure (the devices used to help with sleep apnea) and non-pharmaceutical interventions. In the SIIVA results, they found at least 50 percent of patients had tried some type of alternative therapy, such as acupuncture or herbal teas.
“They’re desperate to get better, and they’re willing to try anything,” Irvin says, “but they don’t want to take a steroid, because they think they will have the same problems of a professional body builder or athlete that abuses steroids.”
The team also has studied the effectiveness of proton-pump inhibitor drugs, commonly used to treat gastroesophageal reflux disease (GERD), and found those didn’t help treat asthma. With additional funding, Irvin says, he would like to look more closely at the potential benefits of exercise and breathing techniques for asthma patients and low dosages of theophylline – an old fashioned asthma medication.
“Maybe there’s some other dietary thing that’ll work,” Irvin surmises. “We just know soy doesn’t.”
(Please note that the American Lung Association recently changed the name of the Asthma Clinical Research Centers to Airways Clinical Research Centers.)