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14 maltatoday | WEDNESDAY • 31 AUGUST 2022 WORLD THERE are two things every- one knows about food aller- gies. One, there's been a big in- crease in recent years, and two, it's caused by our hyper-clean modern lives. Our ancestors would have been exposed to a thousand new pathogens a day, but we live in antiseptic bubbles, so our immune sys- tems aren't used to seeing new things. Those two things that every- one knows are – at best – in- complete. There has been a big increase in the number of people diagnosed with food allergies. That's real, but there has also been a huge increase in public awareness and the availability of diagnostic tests, meaning that many more peo- ple are diagnosed than once would have been. The "hygiene hypothesis", as it is known, is not the whole story, and may not be what's driven the in- crease at all. And the fear of allergies – es- pecially of the shocking, unpre- dictable horror of anaphylactic shock – causes many people to limit their lives and diets in ways that they don't need to and which could harm their health. "There's been a big shift in public awareness of allergy in the last 20, 30 years," says Rob- ert Boyle, a consultant paedi- atric allergist at Imperial Col- lege London. "I think it's got positive and negative aspects. There are aspects of food al- lergy where it's really impor- tant to stay on top of it, but the increased awareness means people are having unnecessary restrictions, and high levels of anxiety around their food, when that's not very produc- tive." For people with real, life-threatening allergies, it's important to be careful – but there are a lot of people who are avoiding foods unnecessar- ily, and it's bad for them. Growing numbers An allergic reaction is when your body's immune system overreacts to something – a drug, something in the air, a foodstuff. It is, says Mr Boyle, typically a reaction like that your body has to suspect- ed parasites: "The pattern of symptoms you see – itching and coughing and swelling and vomiting – is designed to get rid of parasites, which are too big for your white cells to eat. So your body reacts super-fast to expel it. It's an emergency response." There does seem to have been an increase in the number of people suffering from food al- lergies – and other kinds of al- lergy – in recent decades, says Hasan Arshad, a professor of allergy and clinical immunolo- gy at the University of South- ampton. His group looked at all the children born on the Isle of Wight between January 1989 and February 1990, and all the children born there in the same period five years later, and found a surprising increase in allergic responses. The number of children with pollen food syndrome, a mild condition, had gone up from about 2 per cent to nearly 10 per cent, and the number of children with a peanut allergy had gone up from about 0.5 per cent to about 1 per cent. "It's an epidemiological phenome- non over the last 40, 50, years," he says. "Asthma and rhinitis increased in the 80s and 90s, and then there was an increase in food allergies." Margaret Kelman, a special- ist allergy nurse at the charity Allergy UK, agrees: "Allergies have been on the increase. Over the last 40 years and definitely over the last 10 years, we've no- ticed an increase." It's not clear what's causing this increase. Ms Kelman says that the "hygiene hypothesis", the idea that it's down to in- creasingly sterile home envi- ronments, doesn't fit the pic- ture. She suggests that it could be to do with changes to our gut bacteria, perhaps caused by new ways of growing, produc- ing and cooking our food. Mr Arshad wonders if the increase in pollen food syndrome in particular is driven by climate change: "A wider summer pol- len period with increased peaks of pollen." That said, there has also – as Mr Boyle said – been an in- crease in people who think they have an allergy, but don't. "A quarter of people say that they have a food allergy problem," he says. "And that's not real in terms of being objective- ly reproducible. We're living in an era where food allergy is over-emphasised." Mr Arshad agrees that this is a real problem. "Actual aller- gies that can be diagnosed are only about 2 to 4 per cent of the population," he says. "But 20 per cent of the population think they're food-allergic." Partly that's people's self-di- agnoses, but it's also, says Mr Boyle, a systematic over-diag- nosis by medical professionals. "Diagnostic tests have become more available," he says, "and they all tend to over-read. For every two people who get a positive skin-prick test, only one will have a diagnosable al- lergy. For dust-mite allergies, or pollen, or gluten or peanuts or whatever, it's a similar sto- ry." Costs and benefits Awareness of allergies can be good. After all, the paradig- matic example of an allergic attack – anaphylactic shock, the awful thunderbolt-from- a-clear-blue-sky that can kill a previously healthy young per- son in minutes – is a terrifying thing. And even less dramatic versions can be unpleasant to live through. But there are real costs, part- ly caused by a societal hy- per-awareness of allergens, in- cluding a labelling not only of foods that do contain those al- lergens, but of foods that "may contain traces of" those aller- gens. "The may-contain-traces labelling has been tremendous- ly unhelpful," says Mr Boyle, "because it makes the avoid- ance much more difficult. If you try going on a peanut-free diet, it's not very difficult, but if you try to avoid foods that say they 'might contain nuts', then it's much more problematic. And the empirical studies don't find any meaningful reduction of risk from that labelling." Because a lot of people think they have allergies when they don't, or are scared of severe reactions, they often needless- ly restrict their diets. "People are avoiding foods they don't need to," says Mr Arshad. "Half of my work as an allergist is not only diagnosing allergies, but also showing patients that they're not allergic, because it leads to restrictions in their life. I see people who are nu- tritionally deficient – if you're avoiding milk, say, you might Food allergies: People are wrongly self-diagnosing,