Research paper
Effect of a soy isoflavone supplement on lung function and clinical outcomes in patients with poorly controlled asthma: a randomized clinical trial.
Study answer
What this study found
Soy isoflavone supplementation did not improve lung function or clinical outcomes compared with placebo, and it should not be used for patients with poorly controlled asthma. The primary endpoint, change in prebronchodilator FEV1 at 24 weeks, was 0.01 L in the soy isoflavone group versus 0.03 L in the placebo group (P = .36). Plasma genistein increased markedly with soy isoflavone treatment, from 4.87 ng/mL at baseline to 37.67 ng/mL at week 24 (P < .001), while placebo changed from 5.10 to 7.11 ng/mL (P = .22).
- Study & population
- This was a multicenter randomized, placebo-controlled trial conducted at 19 adult and pediatric pulmonary and allergy centers in the United States from May 2010 through August 2012.
- Intervention
- Soy isoflavone tablets were given orally twice daily for 24 weeks, for a total of 100 mg/day.
- Key limitation
- The study was limited to participants aged 12 years or older with poorly controlled asthma and low baseline soy intake, which narrows generalizability.
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Open PDFOriginal abstract
IMPORTANCE Soy isoflavone supplements are used to treat several chronic diseases, although the data supporting their use are limited. Some data suggest that supplementation with soy isoflavone may be an effective treatment for patients with poor asth…