‘Rogue’ bacterium in the nose may be the reason why some people suffer with hay fever, a new study has suggested.

It is well known that gut microbiome – bacteria, viruses and fungi – play an important role in our health and that this mixture supports the immune system and even helps ward off conditions like dementia, heart disease and inflammatory bowel disease.

Scientists already know that having a healthy balance of good and bad bacteria is important – now they have found that this bacterial mix in the nasal passage could play an important role in terms of hay fever.

They have discovered that a specific bacterium appears to boost the immune system’s response to pollen, which in turn intensifies hay fever symptoms.

While researchers look to examine how this particular bacterium can be reduced without impacting healthy bacteria, some suggest that probiotic supplements may provide the answer.

However, other allergy specialists have said that while understanding around hay fever is developing, it is too early to say if nasal microbiome research could transform treatment.

Hay fever occurs when pollen from grass and trees makes contact with the immune cells lining the mouth, nose, eyes and throat.

Problems arise when the body thinks the pollen particles are an infection and releases histamine to try to combat it, which causes hay fever symptoms.

Other research, by the US National Institute of Allergy and Infectious Diseases in Maryland and the Shanghai Jiao Tong University in China, found that whether you have hay fever or not could be determined by the type of bacterial mix within your nose.

In their study, they found that those with hay fever had a smaller mix of bacteria and 17 times as much of one type of bacteria – Streptococcus salivarius.

Another study looked at the effects of taking a daily probiotic powder, with participants who took the powder seeing a substantial reduction in hay fever symptoms compared to a control group.

Dr Karin Ried, director of research at the National Institute of Integrative Medicine and a scientist involved in the study, said: “Probiotics taken orally will work primarily on the gut. But metabolites [by-products produced when probiotics are broken down in the gut] will travel to other parts of the body via the bloodstream and so also indirectly influence the nose.”

Some experts, however, have said nasal microbiome research is still in its early stage.

Professor Adam Fox, a consultant in paediatric allergy at Guy’s and St Thomas’ Hospital in London, said: “It has caught the attention of the allergy community. But the truth is we still know very little about it. We can’t say for certain, for instance, if people with hay fever’s nasal microbiome is like that because they have hay fever, or whether it’s the cause of the hay fever.”

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