An allergy is when the body over reacts to something that is a normal part of the environment. The body treats the entry of this substance like an attack by a dangerous foreign invader.

Common allergens include pollen, dust mites, pet dander, insect stings, medications and foods.

When the allergen enters the body the immune system starts its protective response by making IgE antibodies against the allergen. These antibodies then trigger certain types of immune cell to release inflammatory chemicals into the blood stream. One of these is histamine, which then acts on the eyes, nose, throat, airways, skin, or digestive system to trigger the allergic symptoms.

These include:

• Sneezing
• Runny or blocked nose
• Itchy, red, watery eyes
• An itchy red skin rash
• Swollen lips, tongue, eyes or face
• Swelling the in airways causing difficulty breathing
• Digestive discomfort such as cramps, feeling sick, vomiting or diarrhoea

The exact type of symptoms will depend on how the allergen enters the body, but future exposure to that same allergen will trigger the same immune response. This means that every time the allergen is encountered, the specific allergy symptoms will occur.

So why is it that some people have allergies and others do not?

Scientists are still unravelling what is going on, but what is known is that allergies result from a combination of genetic and environmental factors.

The tendency to allergies can run in families. A person doesn’t usually inherit a specific allergy, just the likelihood of having allergies.

In addition, the immune system is dysregulated. The branch that deals with threats outside of our cells becomes overactive and there are not enough regulatory cells to keep it in check. This imbalance is thought to originate from a lack of exposure to unharmful bacteria in infancy and a lack of friendly bacteria in the gut.

About 70% of the immune system is located in the gut and this is where immune cells learn what to attack and what is a normal part of our environment. The diversity of inputs the immune system sees via the gut is an important factor in ensuring there are enough regulatory cells to keep the immune system in balance.

Diagnosis and treatment

Sometimes doctors can diagnose allergies based on the symptoms and when they occur. However, if the allergy is severe or it’s not clear what the sufferer is reacting to skin prick testing may be used. This involves putting a drop of liquid onto your arm that contains the potential allergen. The skin under the drop is then gently pricked. If an allergy to the substance exists, a raised, itchy, red bump will appear within 15 minutes.

For food allergies, sometimes an elimination diet is used. The possible problem foods are removed for a few weeks to see if symptoms improve, then reintroduced to establish whether they were responsible for the allergic response. This is only suitable if the allergic response is mild and not life-threatening.

Treatment for allergies depends on how severe the reactions are:

Sufferers are advised to avoid the allergen as much as possible, for example staying away from grassy areas during the summer if they have hayfever, or avoiding eating a particular food.
Antihistamine and decongestant medication is prescribed to reduce allergy symptoms such as itchy eyes and a streaming or blocked nose
Steroid medications may be recommended to suppress the immune system. These can be inhalers for respiratory symptoms or creams for skin reactions.
For severe allergies, sufferers will be required to carry an epi-pen containing injectable adrenaline. This will mitigate the symptoms of anaphylaxis – a life-threatening allergic response where the airways close off and blood pressure can drop dangerously low
How can functional medicine help?

Whilst functional medicine isn’t an option during an acute allergic response it can help in other ways. A functional medicine practitioner can:

• Identify what foods you might be allergic by guiding you through an elimination diet.
• Uncover other types of allergies using functional blood tests.
• Give practical advice on how to minimise allergen exposure
• Create a balanced allergen-free diet plan
• Encourage the production of regulatory immune cells by working on the gut.
• Reduce the body’s inflammatory response using dietary changes and specific supplements
• Advise parents on how to minimise allergy risk in children.