Probiotics contain live microorganisms, so-called good bacteria that colonize the intestine. They're sold as supplements but are also found naturally in many fermented foods such as yogurt.
Probiotic drinks could help prevent hay fever
The small study showed that probiotic or "good" bacteria in a daily drink can change the immune system's response to grass pollen -- a common cause of allergies -- and balance antibodies in a way that may provide relief to people with the condition.