A recent study by Visaggi et al. (2023) found that pollen season can reduce the effectiveness of a common diet treatment for Eosinophilic Oesophagitis (EoE). 

The treatment is called the six-food elimination diet (6FED), and it involves avoiding six foods that are known to cause reactions in people with EoE: milk, eggs, wheat, soy, nuts, and seafood. The 6FED can help reduce the inflammation and symptoms of EoE in many patients.

What is Eosinophilic Oesophagitis?

Eosinophilic Oesophagitis (EoE) is a chronic condition, the most common of the eosinophilic gut disorders, occurring in approximately 1 in 1,500 people. EoE is a chronic disease affecting the oesophagus, the tube connecting the mouth and stomach. Too many eosinophils, a type of white blood cell, in the oesophagus causes inflammation, making swallowing difficult.

Food allergies often trigger EoE, but other factors may also play a role.

One of these factors is pollen. Pollen is a fine powder that plants produce to reproduce. Some people are allergic to pollen and have symptoms like sneezing, runny nose, and itchy eyes when they breathe it in.

Methods

The study compares outcomes of patients with EoE who underwent 6FED during vs outside of the pollen season. Fifty-eight patients were included, 62.0% had positive skin prick test (SPT) for birch and/or grass (sensitised to pollen), whereas 37.9% had negative SPT (not sensitised to pollen).

Results

The study showed that patients who were allergic to pollens (such as birch and grass) had lower response rates to the 6FED during the pollen season compared to outside of it. 

This means that even if they avoided the six foods, they still had high levels of eosinophils in their oesophagus during the pollen season. The study also found that patients who were not allergic to pollens had similar response rates to the 6FED regardless of the season.

The authors suggest that pollens may act as a second trigger for EoE in patients who are sensitised to them. 

Pollens may enter the oesophagus through inhalation or swallowing and cause an allergic reaction that worsens the inflammation. 

The SPT for pollens may identify patients who are less likely to respond to the diet during the pollen season.

Read more about Eosinophilic-Associated diseases (EADs)

Read the full article