How your gut is connected to hay fever and allergies

I bet you are wondering, ‘how can my water eyes, running nose and sneezing be connected to my gut?’. As you may have noticed today, there are studies coming out linking all sorts of conditions and diseases to the health of your gut. Allergic rhinitis, commonly known as hay fever, is no different. 

For starters our digestive system plays a huge role in the balance of our immune system. Almost 70% of our entire immune system is located in our gut(1). For hay fever and other allergic diseases the ‘hygiene hypothesis’ was thought to have a role in the increase in allergies, with the lack of exposure to microbes in early life increasing the risk of allergies in later life(2). Now something called the 'microbiota hypothesis' is thought to play a role, meaning a change in our gut bugs influence the development of our immune system(3). Although allergies are also influenced by genetics, some of the environmental and lifestyle factors that change your gut bacteria and increase your risk for allergies include infant use of antibiotics, formula feeding and being born by caesarean section(4,5). Oppositely, growing up with pets(6), growing up on a farm(7), being born through vaginal delivery and being breast fed has been linked to positively influencing your gut’s flora to include more ‘protective strains’(4,5).

What your body does in an allergic reaction

For an allergy to exist, allergen sensitisation must first occur. Special immune cells present in the mucosal surfaces of the body such as nose, lungs and gastrointestinal tract, detect the allergen. One type of immune cells comes into contact with the allergen which are then displayed on the cell's surface. This cell then lets other immune cells know to produce antibodies (IgE) specific to the allergen. From then on, if you are exposed to that allergen, an allergic response is triggered. The allergen is identified by antibodies (IgE) causing immune cells to release inflammatory mediators, such as histamine (8). Histamine is responsible for the itchy nose and runny nose, red watery eyes and dry cough.

The gut-lung connection

The lining of your gut is structurally very similar to lining of your lungs. If you are someone with allergies, inflammation will tend to happen in both areas, as it is thought that leaky gut may have a role in 'leaky lungs'. Our gut flora are also likely have a major impact on the integrity of the lung tissue(9).

Histamine and your gut

You may think histamine is the bad guy because it is linked to your allergies, but in fact is extremely important for mood, stomach acid, blood vessels, and muscle functions (10). The problem with histamine is for some people they can be suffering from histamine intolerance. This means they produce excess histamine and/or have a deficiency in the enzyme that breaks it down. When it comes to our gut, some of our microbes are capable of producing histamine. These microbes produce an enzyme, which converts histidine into histamine. The more of these microbes you have, and the more histidine you consume, the higher the amount of histamine you can produce. Histamine can be then be absorbed and taken around the body, exacerbating allergic symptoms (11).

How to improve your allergy symptoms

1. Heal your gut. Gut health and healing isn't straight forward and may require a professional to guide you. There may be other gut issues at play, like Small Intestinal Bowel Overgrowth (SIBO) driving gut inflammation and increased intestinal permeability (leaky gut), which will also need to be addressed.

2. Balancing gut flora can balance your immune system. This means probiotics from capsules or fermented foods. Be careful with fermented foods if you are histamine sensitive though, as they are a source of histamine. If you feel worse on bone broths or foods like sauerkraut then get in touch with a trained professional to help you refine your diet and introduce these gut healing foods slowly. Some strains that can help reduce histamine include Bifidobacteria infantis and Lactobacillus plantarum (12, 13).

3. Eat fermentable fibre. Eat a diet full of complex, fermentable fibre as it helps intestinal microbiota make short chain fatty acids (SCFAs). SCFAs help regulate the immune system and decrease allergic airway inflammation (14). 

4. Try eating low-histamine diet. Following a low-histamine diet can help reduce the severity of allergy symptoms. Foods to avoids that are high in histamines include canned and ready meals, fermented foods, aged and matured foods like cheese, fish, shellfish, avocados, spinach, cocoa and leftover meat (15).

5. Eat foods high in quercetin or take a supplement. Quercetin is a natural antihistamine and can be found in foods like grapefruit, onions, apples, black tea, leafy green vegetables and beans. Some herbs like Ginkgo biloba and Sambucus spp. are also sources.

6. Zinc. Zinc is a key nutrient involved in maintaining a healthy immune system. It is also necessary in healing and maintaining a healthy gut wall. Supplementing with zinc could significantly help in the healing of leaky gut(16). To find out your zinc levels and get the safest, and get most appropriate zinc supplement, see one of our professionals. Eating foods rich in zinc can also help including grass-fed beef, oysters, lamb, chickpeas, pumpkin seeds, cashews, chicken, spinach and mushrooms.

7. Eat local, raw honey. Raw honey contains both beneficial bacteria and trace amounts of pollen picked up by the bees from local plants. By eating raw honey, you can 'educate' your immune system to tolerate these local pollens (16). By local we mean the neighbouring suburbs, postcode or city. Australian honey isn't considered 'local' as the plants in Perth are very different to that in Melbourne, for example. 

8. For symptom relief try clearing your nasal passage using a neti pot. If any allergens are stuck in the passage this can clear them out and give some temporary relief.