Washington, June 3 : Scientists at the Institute of Food Research say that probiotic bacteria in a daily drink may beneficially modify the immune system's response to grass pollen, a common cause of seasonal hay fever.
The researchers say that they have noted such beneficial changes in a human study.
They, however, have also made it clear that they are not recommending people with hay fever to rush to the supermarket shelves, as the changes they observed might not have an immediate effect on symptoms.
"This was a pilot study based on small numbers of patients, but we were fascinated to discover a response. The probiotic significantly reduced the production of molecules associated with allergy," says research leader Professor Claudio Nicoletti.
When a person contracts hay fever, his/her immune system mistakes the infection-causing fungal or pollen spores for harmful invaders, and produces excessive amounts of the antibody IgE to bind to them and fight them off.
The researchers say that IgE stimulates the release of histamine to flush out the spores, and this irritates the airways making them swell and producing the symptoms of hay fever.
During the course of study, volunteers with a history of seasonal hay fever were administered milk with or without live bacteria daily for over five months.
Given the double-blinded and placebo controlled nature of the study, neither the volunteers not the scientists knew who had been assigned the probiotic drinks containing Lactobacillus casei, a bacterial species that has been widely studied for its health promoting properties.
The researchers took the volunteers' blood samples before the grass pollen season, then again when it was at its peak (June), and four weeks after the end of season.
The noted that there were no significant differences in levels of IgE in the blood between the two groups at the start of the study, but IgE levels were lower in the probiotic group both at the peak season and afterwards.
The researchers also found at the same time that levels of the antibody IgG, which in contrast to IgE is though to play a protective role against allergic reactions, were higher.
"The probiotic strain we tested changed the way the body's immune cells respond to grass pollen, restoring a more balanced immune response", says Dr Kamal Ivory, a senior member of the group.
Dr. Linda Thomas, head of science at Yakult UK, who provided the drinks and some of the funding, said: "These are really interesting results. We are delighted that independent scientists found evidence of this biological activity. The project was part of ongoing research into the benefits of our probiotic strain. The Institute of Food Research is well positioned to do this kind of fundamental research, as it is unique in having the right combination of expertise in microbiology, immunology, flow cytometry and human nutrition research."
The researchers are planning further studies to see whether the immunological changes translate into a real reduction in the clinical symptoms of hay fever.