Allergies, Gut Health and the Immune System

Overview

Allergies happen when the immune system reacts incorrectly to a substance that isn’t usually harmful to the body. Pollen, dust mites, pet dander, mould and certain foods are common substances or allergens. When we encounter an allergen, our immune system responds the same way as if it came across something harmful: histamines and other inflammatory chemicals are released. The immune response leads to symptoms like hives, itching, swelling and difficulty breathing. The severity of allergic reactions varies and can lead to anaphylaxis in severe cases.

Allergic rhinitis (or hay fever) is one of the most common allergic conditions affecting millions of people across the globe. New research shows a significant link between gut health and the onset and management of allergic responses, including hay fever.

The role of the gut microbiome in immune function

The gut microbiome is a rich community of bacteria, fungi, and other microorganisms essential for our immune responses and many other digestive and bodily functions. Seventy per cent of immune cells are found in the gut. A healthy microbiome helps to keep immune responses in check. In fact, an imbalanced microbiome (dysbiosis) is known to play a role in immune dysfunction, leading to a higher risk of allergies.

Factors shaping the gut microbiome in early life

Early-life experiences are one of several risk factors for allergies because they influence the development of a healthy gut microbiome right from birth and the subsequent risk of allergic disease.

• Maternal microbiome: A mother’s gut microbiome can affect an infant’s immune system in utero and after birth. A varied and well-balanced maternal microbiome may protect the infant against allergies, while dysbiosis due to diet or antibiotics may increase the risk of allergies.

• Birth method: Vaginally born infants are exposed to the maternal vaginal microbiome, which influences the development of the gut microbiome in newborns. In contrast, caesarean births can limit this early exposure, possibly increasing the risk of allergy in later life.

• Breastfeeding: Breast milk is rich in beneficial microorganisms that help shape the infant’s gut microbiome, enhancing immune development and decreasing the risk of developing allergies. The specific components of breast milk also evolve based on the infant’s needs.

• Antibiotic use in infancy: Antibiotic use early in life can disrupt the gut microbiome, increasing the risk of allergic disease (and gut issues in some cases) later in life.

Gut microbiome and allergic rhinitis

Research shows that allergy sufferers tend to have less diverse gut microbes than those who don't experience hay fever. Studies also suggest that the nasal microbiome may be involved in allergic conditions like hay fever.

What can diet do to gut health and allergy risk?

Optimising gut health can help manage allergic symptoms, support immune and anti-inflammatory responses, and decrease overall allergy risk. It’s also important to remember that this goes both ways—restriction or avoidance of foods leads to a less diverse microbiome, so it's important to make any significant dietary changes with a specialist dietitian who can offer support.

A gut-first approach to allergies

Current research highlights the strong link between gut health and allergies, reinforcing the importance of maintaining a healthy microbiome for overall well-being. While antihistamines and nasal sprays are commonly used to manage allergic rhinitis, addressing gut health through diet and lifestyle changes offers a complementary approach to reducing symptoms. If you experience hay fever or other allergic conditions, improving your gut health may help provide some relief.

Try these dietary strategies:

• Fermented foods: Good bacteria in foods like kefir, kimchi, live yoghurt, aged cheeses, miso and kombucha can help promote a diverse gut microbiome.

• Prebiotic-rich foods: Prebiotic fibre, offered by foods like onions, garlic, bananas, leeks, and asparagus, acts as a fertiliser for beneficial gut bacteria.

• Diverse plant-based diet: Different gut bacteria eat those plant-based fibre sources and can use them to create short-chain fatty acids (SCFAs), which are great for immune health. As a result, research presented by the European Academy of Allergy and Clinical Immunology (EAACI) concludes that dietary fibre plays a vital role in immunity and allergy management.

• Gut:brain connection: Chronic stress is linked to dysbiosis in the gut microbiome and weakens the immune system. Techniques such as meditation, deep breathing, and yoga can, therefore, support gut and immune health.

• Current research amidst changing guidelines: Exposing babies to common allergens such as peanuts, eggs and dairy between 4 and 6 months as part of a balanced diet helps “train” the immune system to tolerate these foods early on, lowering the risk of allergies in childhood and beyond.

Why choose Welbeck?

This article was written by Dr Emily Porter (PhD, RD), a gut health specialist dietitian at The Gut Health Clinic. At Welbeck, we offer expert guidance on digestive health and immune-related conditions, providing tailored support to improve your well-being.

Moreover, our specialist treatment centre in the heart of London allows you to directly access specialist consultants from our dedicated sleep centre and digestive health centres. From initial diagnostics and testing to treatment and recovery/aftercare, you’ll benefit from high-quality care, appointments to suit your availability, and an on-site pharmacy, allowing you to prioritise your health quickly.

For expert insights and personalised care for allergies, visit the Welbeck Allergy Team.