Why are food allergies becoming more common?



Qualified Nutritionist (BSc, MSc, RNutr)
@EmmaThornton
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01 July 2019

Why are food allergies becoming more common?

In the UK, it's estimated that as many as 1 in 12 children suffer from some type of food allergy, but this figure does have the potential to grow.1 In the USA, the Centre for Disease Control and Prevention has noticed a 50% growth in children who suffer from food allergies between 1997 and 2011.2
While there is no one individual factor to blame for this allergy boom, experts have proposed a number of explanations for this sudden growth, ranging from:

  • Pollution
  • Dietary changes
  • Hygiene
  • Early exposure

Today, I'm going to analyse each of these theories, but first I'm going to discuss the most common food allergens, practical steps to take if you do suffer from a food allergy and when you should seek medical help.

What do the experts say?

As I mentioned earlier, although food allergies are becoming more common there is no one underlying factor to blame. Instead, it could be a combination of different issues; however, experts have formed their own opinions and hypothesise over the years, which I'm going to explore here.

1. Pollution

Pollution has become a red hot issue in the past decade and for very good reason. In addition to wreaking havoc on the environment, more and more people are becoming concerned with the impact it could be having on our own health. A study conducted by the University of British Columbia found that exposure to outdoor air pollution during the first year of life was linked to a higher risk of developing allergies to mould, pets and food.3

So, there could be a link between outdoor pollution and allergies but what about indoor pollution? In 2015, the Office for National Statistics stated that approximately 17% of all adults in the UK smoked cigarettes, thus leading to what is deemed as 'indoor pollution'. This is significant in terms of allergies as a study carried out by the Karolinska Institute discovered that babies exposed to tobacco smoke before, or in the first few months of life, had a greater chance of developing asthma or allergies.5

My thoughts on pollution and allergies

Pollution may be linked to allergies but it's not the only piece in the allergy puzzle to be aware of. While exposure to external pollutants can be difficult to control, there are definitely steps you can take to reduce your exposure to indoor pollution – if you are smoker, for example, then, for a myriad of health reasons, it's probably best to consider quitting. There are plenty of resources out there to help you, such as the NHS.

2. Limited early exposure

Parents with a history of food allergies were traditionally encouraged not to introduce their children to allergenic foods until they were older. This was intended to protect children from experiencing an allergic reaction. However, this lack of exposure early on, some argue, could explain why allergies to these foods are now more common.

A study published in the Journal of Allergic and Clinical Immunology found that Jewish children living in the UK were 10 times more likely to suffer from peanut allergies compared to children of a similar genetic background growing up in Israel.6 This, the researchers believed, was because children in the UK weren't exposed to peanuts within the first year of life whereas those in Israel often consumed a snack called Bamba, which was made using peanut butter.

My thoughts

There is no fool-proof way of preventing allergies and, while a lack of early exposure might be contributing to the general rise of food allergies, I still wouldn't advise exposing extremely young children to allergenic food without taking great care, especially if there is a history of allergies in your family.

3. The hygiene hypothesis

First coined in the 1980s, the 'hygiene hypothesis' sets forward the notion that our extreme cleanliness, in recent generations, is limiting our exposure to specific bacteria and germs, thereby weakening our immune system. A weaker immune system might be more likely to overreact to harmless particles such as pollen, thus making us more vulnerable to allergies.

There is some evidence to back this theory up - the British Medical Journal, for example, found that children in larger households were less likely to develop hayfever, in part because of the germs contracted by older siblings.7 However, most experts are now finding that the hygiene hypothesis is slightly out-dated.

Instead, what could matter more is our exposure to friendly microbes and this can be limited by a variety of factors, not just our cleanliness – everything, from the time we spend outdoors to our diet to medications such as antibiotics, can impact our interactions with friendly microbes.

My thoughts

It's definitely true that, compared to previous generations, children nowadays aren't exposed to the same range of germs and pathogens. This could potentially affect their immune systems but I tend to side with the idea that it's our exposure to friendly microbes that really matters. These friendly microbes play a huge role in regulating the health of our gut and immune system – studies have even found that babies and children with food allergies are more likely to be missing certain species of gut bacteria.8

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4. Changing diets

It's no secret that, over the past century, our diets have changed remarkably. It's never been easier to get a hold of fresh fruit and vegetables but, unfortunately not all the changes to our diet have been for the best. Quick and easy convenience food is sought out by many and refined forms of carbohydrates and sugary foods readily line supermarket shelves. This, in the opinion of experts, creates a problem as often the fibre and nutritional content of these foods is very low.

Researchers at Monash University believe a lack of fibre in our diets is responsible for the rise in food allergies. Their conclusion was based off a number of animal-based studies in which mice were artificially bred to be allergic to peanuts. In some studies, mice were fed a high-fibre diet rich in vitamin A and compared against a control group. The mice fed a high-fibre diet exhibited less severe allergic reactions to peanuts compared to the mice in the control group.9

Furthermore, the high fibre diet also changed the gut bacteria of the mice, protecting them against an allergic reaction to peanuts. The researchers even transplanted this altered gut bacteria to some of the mice in the control group and found that this addition helped to protect them too.

My thoughts

Fibre is definitely something we should be trying to include more of in our diets but, while the results of these studies are compelling, it's important to remember that they are animal-based. In order to verify their findings, more human-based trials would need to take place. Nevertheless, I would always recommend getting a healthy amount of fibre in your diet, as I discuss in my blog, 'What's the truth about fibre?'

How do I know if I have a food allergy?

Food allergies occur when your immune system identifies a harmless substance as a threat and begins to trigger an inflammatory response. This can cause a number of symptoms to develop, usually within a moment or minutes of coming into contact with the food particle response.

Common food allergy symptoms

  • Inflammation
  • Hives
  • Itchiness
  • Dizziness
  • Nausea

As you can see, these symptoms are mild; however, there will be cases where the reaction will be more severe, or, in the worst cases, life-threatening. Here a condition known as anaphylaxis will develop which can cause extreme breathing difficulties. Your tongue may swell, your chest will feel tighter and you will struggle to swallow or speak. If anaphylaxis occurs, urgent medical attention will be required.

Food allergies and food intolerances – what is the difference?

A lot of people do get confused when it comes to food allergies and food intolerances, but these are two unique and separate issues. If you have a food intolerance, for example, it means that your digestive system may find it difficult to break down and process a particular type of food, leading to symptoms such as diarrhoea, abdominal cramping, headaches, flatulence and nausea.

Unpleasant as these symptoms might be to experience, they are not life-threatening. In the case of food allergies, unfortunately, as I've mentioned, symptoms can sometimes be life endangering and occur primarily due to how your immune system reacts to a certain food.

In cases of food intolerance, sometimes it is possible to tolerate a small amount of that particular food. This is definitely not the case with allergies, however, as you would need to avoid the allergen in question completely.

What are the most common food allergies?

When it comes to food allergies, there are 13 foods that may be more likely to cause an allergic reaction, although, it's worth remembering that any food could be capable of triggering a reaction:

  • Fish
  • Crustaceans
  • Eggs
  • Milk
  • Molluscs
  • Mustard
  • Tree nuts (walnuts, almonds, etc.)
  • Peanuts
  • Sesame seeds
  • Sulphur dioxide
  • Lupin
  • Celery
  • Cereals containing gluten

Under regulations by the EU, food manufacturers are required to provide allergen information on both pre-packed and non-pre packed food or drink.10 It's also worth bearing in mind that there could possibly be a genetic factor involved with allergies – if your parents are allergic to a specific food, then you may be more predisposed to that food or drink allergy too.

When should I speak to a doctor?

If you suspect that you or your child could be allergic to a particular type of food, then it's always important to speak to your doctor.

They should be able to conduct tests to achieve a correct diagnosis – usually these tests either rely on a blood sample or are carried out as a skin test. A skin test may involve your doctor exposing your skin to a small amount of the allergen, making a small scratch in the epidermis to observe the reaction.

If you feel as though you are taking a reaction to any food, please immediately seek attention from a medical professional or go to A&E. Even if you feel your reaction is mild, it's still important to get them checked out thoroughly to avoid any unforeseen symptoms from cropping up.

1https://www.allergyuk.org/information-and-advice/conditions-and-symptoms/42-childhood-food-allergy

2https://www.cdc.gov/nchs/data/databriefs/db121.pdf

3https://www.sciencedaily.com/releases/2015/05/150504094427.htm

4https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/healthandlifeexpectancies/bulletins/adultsmokinghabitsingreatbritain/2015

5https://www.sciencedaily.com/releases/2008/07/080723170835.htm

6thttps://www.sciencedaily.com/releases/2012/10/121003082734.htm

7https://www.jacionline.org/article/S0091-6749(08)01698-9/abstract

8https://doi.org/10.1038/s41591-019-0461-z

9http://www.cell.com/cell-reports/fulltext/S2211-1247(16)30630-1

10https://www.food.gov.uk/business-guidance/allergen-guidance-for-food-businesses

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