NHS figures reveal the number of people admitted to hospital as a result of allergies has more than doubled since 2013. There are estimated to be over 2 million people living with a diagnosed food allergy in the UK, according to the Food Standards Agency.
A food allergy is when the body’s immune system mistakenly treats proteins found in food as a threat, and anaphylaxis can be life threatening. But it’s important to distinguish between allergies and intolerances, which are caused by difficulty digesting certain foods.
The rise in allergies over recent decades has been particularly noticeable in the West – England saw a 72% in the number of hospital admissions caused by anaphylaxis (an acute allergic reaction) among children between 2013 and 2019, from 1,015 to 1,746.
The increase in numbers is not because we’re more aware of allergies or getting better at diagnosing them, says Dr Alexandra Santos, Consultant in Paediatric Allergy. There are a number of high-profile theories about what’s behind this rise, ranging from lack of sunlight to dietary changes affecting our gut bacteria. While there’s no clear single reason for the increase, the cause is “most likely related to environmental factors and our lifestyle”, says Santos.
Avoiding allergens early in life
Avoiding well-known allergens early in life may increase the risk of developing an allergy, according to King’s College London’s LEAP (Learning Early About Peanut Allergy) study. It found “early childhood exposure to peanut decreases the risk of developing a peanut allergy”, and identified an 81% reduction in peanut allergy among 5 year old children who regularly ate peanut from the year they were born in comparison to those who did not.
The theory behind this finding is called ‘dual allergen exposure’. It suggests that even if children avoid eating allergens, they’ll still be exposed to them through dust, furniture, creams which can trigger an immune response. Where the “development of allergy antibodies takes place through the skin”, particularly through inflamed skin in babies with eczema, before a food has been eaten or drunk, the immune system over-reacts to the food, explains Santos, who was involved in the LEAP study. It is suggested this is why infants with eczema are more likely to develop an allergy.
There is thought to be a “window of opportunity in the early years” to establish tolerance to potential allergens, as “the gut’s immune system is prepared to tolerate…foreign substances, such as food”, says Santos. The NHS website offers advice on introducing foods that can trigger allergic reactions to babies and toddlers.
Is our improved hygiene to blame?
The ‘hygiene hypothesis’ suggests early childhood exposure to bacteria protects against the development of allergies. It proposes that in modern society there is a reduced opportunity for cross-infection in households, due to reduced household size, improvements in household amenities, and better personal hygiene. Many scientists criticise the hypothesis but experts agree good hygiene is important in avoiding and fighting disease.
A recent version of the theory, named ‘old friends’ hypothesis, proposed the issue is not how clean your home is but whether your gut is encountering different microorganisms. Graham Rook, who developed the theory, suggests because we have a long evolutionary association with certain microorganisms, the immune system thinks they are harmless. But our gut microbiota is slowly changing due to our modern lifestyle. So we have fewer ‘old friend’ microbes that help our immune system fight foreign substances.
There is evidence that taking antibiotics in childhood may increase your risk of food allergy as they kill good and bad bacteria. “The microbiome in the gut will likely influence our ability to tolerate food or develop food allergy”, says Santos, particularly in early life.
A diverse diet from weaning onwards “has shown to be protective from development of food allergies”, as it helps develop beneficial gut bacteria, Santos adds. Read more about eating for a healthy gut on BBC Food.
The relationship between Vitamin D and allergy risk
Some research suggests a relationship between sun exposure when young and allergy risk.
A study took place in Australia and the USA. The study examined the amount of allergic reactions and epinephrine autoinjector prescriptions, which acts as a treatment for allergy reactions, across the two countries. They observed lower rate in regions with more sunlight. A further study found that Australian babies born in the Autumn and Winter had a higher rate of food allergy compared to those born in the Spring and Summer. The researchers proposed the correlation could be due to the levels of vitamin D.
However, a German study found those with higher vitamin D rates at birth were more likely to develop a food allergy by 3 years old. Santos says, “we need more robust evidence” to assess the importance of vitamin D in allergy prevention.
In the UK, we don’t get enough vitamin D between October and early March, so The Department of Health recommends many of us take a Vitamin D supplement during these months, or year-round for those who don’t go outside often. It also advises breast-fed babies are given a vitamin D supplement from birth (infant formula is already fortified with vitamins) and all children from one to four years are given a daily supplement containing 10 micrograms of vitamin D.
Introducing new foods to our diet
It isn’t only the rate of allergies that has increased, there has also been a gradual increase in the range foods people are allergic to. Santos suggests this could be due to an increased exposure to new foods, either because they’re being imported or through travel. “This happened a number years ago with kiwi”, she says, “it was not a fruit that was consumed in Europe, but then we started to see kiwi allergy” in the 1980s, after it was introduced.
In theory, “we can be allergic to anything”, says Santos. However “8 groups of food constitute about 90% of food allergies”, she adds. The most common food allergies are cow’s milk, eggs, wheat, soya, peanuts, tree nuts, seeds and fish and shellfish.
The effect of allergies
Responses to allergies range from mild to severe anaphylaxis, which requires urgent medical attention.
There is currently no cure for food allergies, and managing the condition relies on avoiding the food and having an emergency treatment plan in the event of exposure. There are a number of tests for allergies, outlined on the NHS website. But allergies remain a worry and part of daily life for an increasing number of people.
What do Tops do to avoid allergic reactions?
At Tops Day Nurseries, we take potential allergic reactions extremely seriously and so each different food type is labelled with any allergens the food contains. All staff and children have allergy forms and all kitchen staff must be aware of the precautions needed when preparing snacks and meals.
Read the full article
by BBC Food, click here for the full article covering the rise in food allergies.