The participants receiving probiotics showed a small but significant improvement in allergy symptoms.
A link to a review of the study is found here: http://blog.emersonecologics.com/2017/07/20/clinical-research-improving-seasonal-allergies-with-probiotics/?utm_term=Improving%20Seasonal%20Allergies%20with%20Probiotics&utm_campaign=The%20Weekly%3A%20Addressing%20Allergies%20Through%20Inflammation&utm_content=email&utm_source=Act-On+Software&utm_medium=email&cm_mmc=Act-On%20Software-_-email-_-The%20Weekly%3A%20Addressing%20Allergies%20Through%20Inflammation-_-Improving%20Seasonal%20Allergies%20with%20Probiotics
This supports what we know in Chinese Medicine. Probiotics work on the Large Intestine whose meridian is linked to the Lung meridian, which deals with allergy symptoms. When digestion is improved than the body doesn’t create by-products which irritate the Lungs and its opening, the nose, causing them to react to external irritants.
This corresponds with my clinical experience. I’ve seen patients with allergies get significant improvements with treatment and dietary changes.