A new study shows that regular consumption of probiotics can ease seasonal allergies.  Holistic doctors have been prescribing probiotics for allergies for years--this new study lends credence to the practice.  Researchers found that people who regularly consumed a fermented milk product had a decreased immune response to grass pollens that they were previously allergic to.  The following is extracted from an article on yahoo on the study:

"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 same mechanisms are in part why raw milk is far superior to pasteurized milk--raw milk is full of beneficial bacteria and enzymes, whereas pasteurized milk is sterile.  Other health-giving that are full of beneficial bacteria include kefir, yogurt, sauerkraut, miso, tempeh, and kimchee.  I recommend daily consumption of fermented foods.

Read the study here.