Researchers have found that a probiotic combination might help reduce symptoms of seasonal allergies like hay fever.

Hay fever may cause itchy, watery eyes, sneezing and other similar symptoms.

"Not all probiotics work for allergies. This one did," said study first author Jennifer Dennis, a doctoral student at University of Florida in the US.

Scientists already know that the probiotic combination of lactobacilli and bifidobacteria helps maintain digestive health and parts of the immune system.

The researchers wanted to know if the components in this combination probiotic would help alleviate allergy symptoms.

To do that, they enrolled 173 healthy adults who said they suffered seasonal allergies and randomly split them into two groups -- some took the combination probiotic and others took a placebo.

Each week during the eight-week experiment, participants responded to an online survey to convey their discomfort level.

Scientists also analysed DNA from participants' stool samples to determine how their bacteria changed, because probiotics aim to deliver good bacteria to the human's intestinal system.

The DNA test also confirmed who was taking the probiotic, senior author of the study Bobbi Langkamp-Henken, Professor at University of Florida said.

The researchers conducted the experiment at the height of spring allergy season.

Participants who took the probiotic reported improvements in quality of life, compared to those taking the placebo, showed the study published in the American Journal of Clinical Nutrition.

Researchers noted that this study did not include severe allergy sufferers.

But the combination of probiotics showed clinical benefit for those with more mild seasonal allergies, Langkamp-Henken said.

The researchers believe that probiotics might work by increasing the human body's percentage of regulatory T-cells, which in turn might increase tolerance to hay fever symptoms.