Allergic reactions to foods are a growing, potentially life-threatening problem. The good news is we can turn this around, says Kari Nadeau

Health


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10 March 2021

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Michelle D’urbano

FOOD allergies have been on the rise. In the US, it is now estimated that over 10 per cent of the adult population has an allergy to peanuts, shellfish, dairy or another food. In the UK, the past three decades have seen hospital admissions for food allergies rise fivefold. Thankfully, we are building up the armoury needed to reverse this trend so that, one day, such potentially deadly reactions become a thing of the past.

The most common types of food allergies are triggered by antibodies that we make called immunoglobulin E or IgE. These antibodies were discovered in the mid-1960s and kick-started an era of allergy research still going strong today. The early findings have spawned thousands of studies that paint an intricate picture of how allergies work, suggesting ways in which we can prevent and treat them.

When someone has a food allergy, IgE is involved in triggering a response when the immune system comes into contact with that food. Essentially, the body sees that part of your meal as an enemy, releasing histamine and other inflammatory chemicals in an attempt to deal with it. This causes symptoms ranging from itchiness and sneezes to wheezing and anaphylactic shock. The result can be anything from a mild inconvenience to death.

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We have yet to get to the bottom of why the body sometimes sees harmless substances in this way, but we now know much more about stopping this process from happening in the first place.

The old saying “prevention is better than the cure” holds true for food allergies. My colleagues and I use the so-called six Ds as a guide to preventative measures during childhood: diet, dirt, dogs, dry skin, detergents and vitamin D. Studies have found that people have a lower risk of developing an allergy when, as youngsters, they eat a diverse diet and do so often, have healthy vitamin D levels, live in a home with a dog, avoid dry skin and are exposed to dirt, allowing them to develop a good microbiome. The use of harsh detergents has also been associated with an increase in IgE.

There is also evidence to suggest that when children consume potentially allergenic foods early in their lives, this trains the immune system to accept them.

Clearly, for many people that have food allergies, such early life prevention is no longer an option. However, other approaches are taking shape.

Most of the interventions we currently use target the immune system in an effort to retrain its response to allergens. One technique, known as allergen immunotherapy, involves slowly building up exposure to a problem food. By starting in very small doses, the body appears to be able to be retrained to no longer see it as a threat. People with reactions to peanuts, egg, milk or even to multiple foods have found success using this method. However, immunotherapy needs regular exposure to allergens, which can cause side effects.

There are also anti-IgE drugs that can block the antibodies involved and raise your threshold for a particular allergen before it makes you ill. These can be particularly useful when used with allergen immunotherapy to help people become desensitised to troublesome ingredients.

Allergy vaccines are another option. These work by reshaping the body’s immune response to a particular food so it doesn’t end in illness. One example is a vaccine that has been used to help people with peanut allergies.

As we gain evidence and experience with each of these approaches, we are moving closer to being able to treat all food allergies. Many of us around the world are aiming to forge a new era, one in which this scourge is a thing of the past.

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