Based on the Hay Fever Survey 2026 conducted by major Japanese weather forecasting company Weathernews Inc and published in February this year, more than one in two respondents reported having hay fever.
In recent years, in addition to nasal symptoms such as sneezing and runny nose, ocular symptoms including itchy eyes, tearing, foreign-body sensation, and allergic conjunctivitis can significantly disrupt daily life. Due to its impact on quality of life (QOL), hay fever is increasingly recognized as a public health issue.
According to Kirin, the prevalence of hay fever in Japan is 40%. In particular, the prevalence of Japanese cedar pollinosis has increased by approximately 10% over the past decade.
In previous research, Kirin found that Lacticaseibacillus paracasei KW3110 (L. paracasei KW3110) activates dendritic cells and macrophages, which are innate immune cells, and enhances their ability to produce Th1 cytokines, and alleviates allergic symptoms.
L. paracasei KW3110 is a lactic acid bacterium discovered through joint research conducted by Kirin and Koiwai Dairy Products Company. Selected from more than 100 strains and originally isolated from cheese, it has been studied for its potential to support immune balance.
A clinical trial conducted by Kirin’s Health Science Research Institute—which evaluated the effects of consuming a food containing L. paracasei KW3110 on nasal and ocular symptoms associated with mild to moderate hay fever—confirmed relief of ocular symptoms, particularly during periods of high pollen dispersion.
These findings were presented at the 75th Annual Meeting of the Japanese Society of Allergology (JSA), held at the Kyoto International Conference Center from October 15 to 18, 2026.
Kirin believes that the insights gained from this study are meaningful for research addressing the challenges faced by people whose QOL is diminished by allergic symptoms.
“There is growing demand for the development of safe products that use beneficial food-derived ingredients to alleviate allergic symptoms with fewer concerns such as drowsiness,” the company stated.
Through continued research on L. paracasei KW3110, Kirin aims to support the development of products that tackle these challenges.
Study method
Allergic reactions such as hay fever are closely linked to immune cells such as Th2 cells. Excessive activity of these cells induces Type 2 inflammation, which contributes to the onset of allergic symptoms.
The company believes that preventing the exacerbation of Type 2 inflammation is important, since allergic symptoms occur when these immune cells produce strong inflammatory responses to substances such as pollen, dust mites, and house dust.
Kirin previously reported that compared with other lactic acid bacteria, L. paracasei KW3110 has a stronger ability to induce the production of cytokines that suppress Type 2 inflammation, including interleukin-12 (IL-12).
The study presented at the Annual Meeting of the JSA was designed as a randomized, double-blind, placebo-controlled trial.
A total of 130 men and women aged 20 to 65 years who experienced nasal and ocular discomfort in early spring, were classified as having mild to moderate allergic rhinitis, and did not regularly use medications to alleviate their symptoms were enrolled.
The participants consumed either a functional food containing 50mg of heat-killed L. paracasei KW3110 (equivalent to at least 140 billion cells) or a placebo for eight weeks.
Self-reported nasal and ocular symptoms were assessed using the Japanese Allergic Rhinitis Standard Quality of Life Questionnaire No.1 (JRQLQ No.1), while the severity of allergic rhinitis symptoms was evaluated based on a physician’s diagnosis.
Compared with placebo, consuming food containing L. paracasei KW3110 led to significant improvements in self-reported symptom scores for “ocular symptoms” and “concern about others’ perceptions” at weeks six and eight of the study, which also corresponded to periods of high pollen dispersion.
