"Good" bacteria may ease hay fever symptoms: study

A bee collects pollen from a spring flower in a forest near the village of Banyalbufar, in the Spanish island of Mallorca April 3, 2006.

LONDON (Reuters) - A probiotic drink a day may help keep hay fever away, British researchers said on Tuesday.

A 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.

"These data show that probiotic supplements modulate immune responses...and may have the potential to alleviate the severity of symptoms," Claudio Nicoletti and colleagues at the Institute of Food Research in Norwich, Britain, reported in the journal Clinical and Experimental Allergy.

Probiotics contain live micro-organisms, so-called good bacteria that colonize the intestine. They are sold as supplements but are also found naturally in many fermented foods, including yogurt and certain juices.

Humans normally carry several pounds of bacteria in their intestines and they are key to digestion, immune system function and possibly play other beneficial roles. They can also out-compete "bad" bacteria that may cause disease.

"The probiotic strain we tested changed the way the body's immune cells respond to grass pollen," added Kamal Ivory, a researcher who worked on the study.

In the study volunteers with a history of seasonal allergies drank a daily milk drink with or without Lactobacillus casei -- a bacteria widely studied for its beneficial properties -- over a five-month period.

The researchers took blood samples before the grass pollen season, at its peak and after the end of season. They found that people who had been drinking the probiotic drink had lower levels of an antibody that help produce allergy symptoms.

At the same, these people also had higher levels of a different antibody, called IgG, that may play a protective role against allergic reactions.

These changes may reduce the severity of symptoms, something the researchers said they plan to test further. They also cautioned that the findings came from a small study and more work was needed.

(Reporting by Michael Kahn; Editing by Maggie Fox and Jon Boyle)