Editor's note, Jan. 17: Some identifying information has been removed from this report to guard the privacy of the family that is part of the probiotics test.
It's a typical hectic morning at Michele's house in Northern Virginia when she gets a knock on her front door.
"Hi, how are you?" she says as she greets Keisha Herbin Smith, a research assistant at Georgetown University. "Come on in."
Michele, 39, leads Herbin Smith into her kitchen.