Mean changes in prebronchodilator FEV1 over 24 weeks were 0.03 L ( 95 % CI , -0.01 to 0.08 L ) in the placebo group and 0.01 L ( 95 % CI , -0.07 to 0.07 L ) in the soy isoflavone group , which were not significantly different ( P = .36 ) .