Are Food Allergies On The Rise?

Twenty years ago, as a child with an allergy to cow’s milk and a vegetarian, gluten-intolerant mother, I saw some strange school lunches in my time. While other kids feasted on all the things I wasn’t allowed to eat (White bread! Soda! Weird, processed cheese that comes in a tube!), I cowered in the corner with my nutmeat sandwiches on rye bread with soy butter, cursing my over-excitable histamines.

Yes, I was THAT kid at school – that is, until Peanut Allergy Boy arrived and stole my thunder. At the time, we felt like the odd ones out. Now, it seems as though many more people have (or are aware of) food intolerance and allergies. Some countries are encouraging peanut-free school environments, and more and more restaurants are offering allergen-free options on their menus.

These days, do more people actually have food allergies, or does it just seem that way? If so, is this increase due to our environment, changes in diet and lifestyle or our genes? Although population data for allergy prevalence are difficult to collect, a recent scientific study (Branum & Lukacs, 2008) indicates that incidences of food allergy are most likely increasing, although an explanation for this trend has yet to emerge.

What are allergies? Who has them, and why don’t we know more?

We currently don’t have much information about the prevalence or distribution of food allergies amongst the population, for a number of reasons.

To start with, people often aren’t sure if they have an allergy or not. The term allergy is often misused when a person experiences symptoms which resemble an allergic response. True allergies occur when the body responds immunologically (by producing an antibody, such as immunoglobulin E [IgE]) to a certain food. This antibody will recognize the offending food type, and trigger an immunologic reaction, causing symptoms such as hives, vomiting, swelling around the mouth, stomach pains, diarrhea or, most seriously, anaphylaxis (affecting the breathing and circulatory systems). (FDA 2009; FAAN, 2009; Madsen, 2005)

In contrast, food intolerance (or sensitivity) induces an abnormal symptomatic response, but does not involve the immune system. For example, people with lactose intolerance often have stomach pains or diarrhea after consuming milk products, but this is caused by a lack of lactose enzymes or metabolites, rather than an immune response. (FDA 2009; FAAN, 2009; Madsen, 2005)

The majority of surveys of food allergy prevalence rely on self-reports, yet the general population do not usually differentiate between IgE-mediated food allergies, non-IgE-mediated food allergies and non-allergic hypersensitivities or intolerances. In addition, symptoms of food allergy may overlap with those of food poisoning, or other illnesses. As such, people often think they have an allergy or intolerance when, in fact, they do not. Survey results are thus often highly variable, and not always a true indication of population data. (Madsen, 2005; Rona et al., 2007)

What we do know is that hospital admissions for anaphylaxis have doubled over the last decade in Australia, USA and the UK (ASCIA, 2009). However, this increase could be due to higher awareness of allergy dangers, as more patients are referred to hospital for less severe symptoms in recent years than in the past. Hence, increases in hospitalization are not necessarily indicative of the increase in allergy cases. (Rona et al., 2007)

What DO we know?
Despite the lack of concrete, widespread data, many doctors, scientists and nutritionists alike have noted a significant increase in their treatment of allergy and intolerance cases in the past ten years (Mullins, 2007). In 2008, Branum et al., using data from the National Health Interview Survey and the National Hospital Discharge Survey, found that:
•    In 2007, approximately 3 million US children under age 18 years (that is, 3.9%) reportedly had a food or digestive allergy.
•    This figure had increased by 18% since 1997.
•    Children with food allergy are two to four times more likely to have other related conditions, such as asthma or eczema than children without food allergy.
•    Food allergy is most common in children under five years, and less common in adults who often “outgrow” the condition.
•    Male and female children had similar rates of incidence.
•    Hispanic children showed lower rates of reported food allergy than non-Hispanic children. Children from other ethnicity groups had statistically similar rates of allergy prevalence.

While more than 160 allergens have been reported in the US, this study supported findings that only eight types of foods (and products which contain them) account for 90% of all food allergies in the US: milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat (ASCIA, 2009; Crooks et al., 2008; Kagan, 2003; Mullins, 2007). By law, these eight major allergens must be identified of the label of any food product, as avoiding them is the only way to prevent a reaction (FDA, 2009). Cow’s milk and derived dairy products were identified as the major cause of allergic responses (FDA, 2009), while peanut allergies are reportedly on the rise, causing the highest number of allergy-related fatalities in the US in recent years (EMBO, 2006). Reported cases of gluten and lactose intolerance have increased, perhaps as each condition has garnered more attention and awareness recently.

Why do we see this rise in allergy prevalence?
We don’t yet know what causes food allergies or intolerances, therefore we don’t know why they’re becoming more common.

Some people suggest increased allergies are a result of globalization of our dietary habits, one report noting that kiwi fruit allergies rose in the US recently, simply because more people in the US are now eating the fruit. A similar phenomenon has occurred in countries whose populations traditionally consumed fewer wheat products, with wheat allergies increasing following a rise in Western-style diets. (EMBO, 2006)

Others suggest that changes in food-manufacturing may be to blame. Dry-roasting peanuts, for example, was shown to increase allergenicity compared to boiling or frying peanuts. (EMBO, 2006)

One common theory is the Hygiene Hypothesis (ASCIA, 2009), which suggests that less exposure to infections and bacteria in early childhood is associated with increased risk of allergy due to an inadequately developed immune system. This has not been proven in studies, and critics argue that though children may be more commonly vaccinated and “protected” from germs, the modern environment is, if anything, more bacteria-laden than it used to be.
Whatever the cause or causes may be, with approximately 30,000 emergency room visits and 150-200 fatalities each year in America alone, food allergies are serious conditions, which require more research. While it may have comforted me twenty years ago to learn I wasn’t the only kid who had allergies, rising rates of the condition are surely of much concern, especially if this increase is caused by modern-day environmental or dietary factors which could be prevented. In the mean time, the only way to avoid an allergic response is to avoid the allergen – which means reading labels, and knowing at all times what is in the food you eat.

References

Australasian Society of Clinical Immunology and Allergy website(2009) Viewed online July 7 2009: http://www.allergy.org.au/
Branum, Lukacs for Centre of Disease Control and Prevention (2008) Food Allergy Among US Children: Trends in Prevalence and Hospitalizations. Viewed online July 7 2009: http://www.kidswithfoodallergies.org/resourcespre.php?id=129&title=food_allergy_prevalence_hospitalizations_US_children
Crooks et al. (2008) The changing epidemiology of food allergy – implications for New Zealand. Viewed online July 7 2009: http://www.nzma.org.nz/journal/abstract.php?id=2982
EMBO (2006) Food allergies on the rise? Viewed online July 7 2009: http://www.nature.com/embor/journal/v7/n11/full/7400846.html
FDA Consumer Health Information (2009) Food Allergies: Reducing the risks. Viewed online July 7 2009: http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm089307.htm
Food Allergy and Anaphylaxis Network (2009) FAQs. Viewed online July 7 2009: http://www.foodallergy.org/questions.html
Kagan (2003) Food Allergy: An overview. Viewed online July 7 2009: http://www.ehponline.org/members/2003/5702/5702.pdf
Madsen (2005) Prevalence of food allergy: an overview. Viewed online July 7 2009: http://journals.cambridge.org/download.php?file=%2FPNS%2FPNS64_04%2FS0029665105000509a.pdf&code=d1261edc062eb55fc3e652438a6bb5dd
Mullins (2007) Paediatric food allergy trends ina community-based specialist allergy practice, 1995-2006. Viewed online July 7 2009: http://www.mja.com.au/public/issues/186_12_180607/mul11320_fm.html
Rona et al. (2007) The prevalence of food allergy: A meta-analysis. Viewed online July 7 2009: http://www.ncbi.nlm.nih.gov/pubmed/17628647

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