Gut Health & Seasonal Allergies

Have you ever considered that gut health may be a key factor in the development of seasonal respiratory allergies such as rhinitis, hay fever and asthma?  Each year as spring draws, millions of Australians experience flare ups of these debilitating conditions, manifesting symptoms such as blocked nose, itchy, swollen and sore eyes, difficulty breathing and wheezing. Ongoing research has been conducted to ascertain potential underlying causes of these increased seasonal reactions.

Historically the "hygiene hypothesis" was believed to be a compounding factor in the development of conditions such as hay fever. This was based on Strachan's observation that there was an inverse relationship between development of hay fever and birth order. Studies have since shown that incidence of such conditions may not in fact be a result of increased microbial infection in early life, but rather reduced microbial colonization. Stool analysis studies showed that children with allergies (ie. Atopic eczema, asthma, hay fever) had lower levels of Lactobacillus and Enterococcus and higher incidence of pathogenic organisms such as Bacteroides, Clostridium and Staphylococcus. Further studies even confirmed that babies with low levels of Bifidobacteria in comparison to higher levels of pathogenic organisms, were more likely to develop allergic conditions later in life. More-so studies have now confirmed that in fact gut microbiota begins to establish in foetal life and may influence the development of allergic conditions, indicating the maternal gut microbiota may in fact determine the diversity of foetal microbial environment. 

This imbalance of beneficial and pathogenic organisms and overall gut environment, known as dysbiosis, has been found to have an effect on the regulation of the immune system and thus contribute to the onset of allergic conditions. Many contributing factors are believed to be associated with the development of these allergic conditions such as increased antibiotic use, mode of child delivery, increased psychological and physical stress and the western diet. Interestingly, these same factors also affect gut microbiota. 

Short Chain fatty acids (SCFA) must also be considered. The gut microbiota ferments dietary fibre producing SCFA required for the production of energy for colonic epithelial cells a well as overall energy production, anti-inflammatory properties and have recently been found to be involved in metabolism and immune system support. Research has shown that there is a correlation between the immune function of the respiratory tract and the immunomodulatory activity of gut microbiota displaying that gut microbiota affects overall systemic immunity which in turn affects lung mucosa and therefore the resulting symptoms associated with this. 

It seems that the microbial environment and gut health have a direct part to play in supporting overall immune health and the incidence of seasonal allergic conditions such as hay fever, rhinitis and asthma and therefore should not be overlooked when assessing seasonal allergies.