Sitting in my mum’s kitchen, I bit into a sugar snap pea, as I’ve done a hundred times before. But this time my eyes started to itch. I tried to blink, but my eyelids were stuck together. Sprinting to the bathroom mirror, I saw someone who could have just gone 10 rounds with Laila Ali: my upper lip had gone all Angelina Jolie, and my right eye was swollen shut.

“What happened?” my mum screamed.
“I think I’m having an allergic reaction to the peas,” I squeaked, my throat closing up.
“But you don’t have food allergies!”

I do now. Once my swelling subsided, I set out to learn why.

The news is not good: according to the Australasian Society of Clinical Immunology and Allergy (ASCIA), the number of hospitalisations due to anaphylaxis from food allergies has doubled in the past 10 years, which is a massive, inexplicable rise.

“[Food allergies] are definitely on the increase,” says gastroenterologist and allergy researcher Katie Allen. “We’re not sure why this is, but the most common reason is our developed lifestyle. There’s evidence to show that people in less developed countries have fewer allergies than those living in developed countries.”

Immunity meltdown

Food allergies are serious. When you have an allergy your body reacts to a particular food – in my case, the pea – as if it were a bacterial or viral invader hell-bent on causing harm. Your immune system goes on full alert, producing loads of immunoglobulin E (IgE), an antibody that travels through the blood to your body’s entry and exit points – nose, mouth, throat and GI tract. There, the antibodies attach to mast cells, which release histamine; that triggers swelling meant to keep the invaders from going deeper into your body (throat closing), while your insides act to get rid of the ones already in your system (diarrhoea).

Children tend to suffer more food allergies than adults because their immune systems are still in training. By the time they reach high school, the body has usually sorted the friendlies from the threats. But in rare (though increasingly numerous) cases, adult defences tag a previously innocent food as Enemy Number One. Experts aren’t sure why this is happening more often but they suspect three possible causes:

1. Global warming Yet another reason to use energy-efficient light bulbs and take short showers: the increase in carbon dioxide and higher temperatures make plants and trees generate more pollen, which may be causing a significant increase in seasonal allergies. The ASCIA reports that one in four of us may now suffer from hay fever which can be attributed to airborne allergens – up from one in five in 2001. “There’s a lot of evidence of what’s called a topical march, and that’s when you have a propensity to eczema and allergy in the first three years of your life, which eventually calms down, and then you develop hay fever later in life,” says Allen.
2. Antibiotics Some docs believe that the rise in food allergies may be linked to a phenomenon known as leaky gut. The problem occurs when food compounds that your digestive system hasn’t adequately broken down pass through your GI tract and into your bloodstream. Our bad habit of taking antibiotics at the first sign of illness can kill the good bacteria that keep the GI tract intact. Without those good guys, openings can develop, allowing food particles to slip out, explains Gary Huffnagle, author of The Probiotics Revolution ($42.95, Ebury Press) and professor of internal medicine, microbiology and immunology at the University of Michigan Medicine Center, US. These leaked bits put your immune system on edge, and allergic reactions ensue. There’s currently no cure, but Huffnagle says a daily probiotic (such as Inner Health Plus) may help.
Allen adds, “It’s not proven that taking a probiotic is useful, but they’re fairly safe so there’s probably no harm in trying them.”
3. Your workout Don’t use this as an excuse, but there seem to be increasing accounts of women in their 20s and 30s suffering reactions to particular foods after they step off the treadmill. Experts aren’t sure why, but if you are one of them, keep an exercise and food journal, note symptoms that repeatedly occur after a workout, and tell your doctor.

Allergy v intolerance

Are we headed for an allergy epidemic? It’s hard to tell. There are countless stats about kids and food allergies, but info on adults is scant. Estimates on how many adults have food allergies run as low as just one in 100 people. Yet surveys state a whopping one in three think they have a food allergy. Experts blame the discrepancy on a lack of information and “me too” syndrome. “We recently ran a web-based survey which showed one in three households believe they had a food allergy,” says Allen. “Not all were doctor-diagnosed though, so it’s likely that some were intolerances.”

Unlike allergies, intolerances trigger digestive problems, not immune responses. Your GI tract can’t process a certain food component – such as lactose or gluten – so your body goes into evacuate mode. Next thing you know, you have diarrhoea, vomiting, cramps, a headache (fun!). When you google these symptoms, you’ll see them linked to both food allergies and food intolerance.

So how do you tell the difference? Allen says that allergies are likely to cause a response – anaphylaxis, hives, swelling – in about 30 minutes, while intolerances are more likely to trigger gastro-intestinal problems such as diarrhoea at least an hour after digesting the suspect food. If you’re still concerned, see an allergist, who can conduct a skin test to determine what, if anything, you’re allergic to. If your test comes up empty, you probably have an intolerance. He or she may also put you on an elimination diet, where foods commonly associated with allergies and intolerances will be taboo until you’re symptom-free. Then they’ll be reintroduced one at a time over several weeks until you find the edibles causing you distress.

The good news? If you’re prone to severe reactions, keep in mind that food-labelling laws require manufacturers to list whether a food contains any of the top eight allergens: milk, eggs, fish, shellfish, peanuts, tree nuts, wheat and soy. As more alternatives arrive on the shelves every day, an allergy or intolerance doesn’t mean a lifetime of limitation. You may find – as I did when I ditched sugar snap peas for edamame – that it opens you up to a whole new world of eating.