The truth about food allergies

Scared of dairy? Avoid wheat like the plague? These days, it seems everyone has an intolerance or allergy. But are there genuine health reasons to give up certain foods - and how can you tell if you should? Maria Lally investigates

When Gwyneth Paltrow became the poster girl for a gluten-, dairy- and egg-free diet, the notion of cutting out an entire food group seemed like the preserve of celebrities who had a private chef to tend to their dietary needs. Fast forward ten years and ditching a food group for your health isn't just popular, it's everywhere. Instagram is awash with #wheatfree and #sugarfree hashtags, and food bloggers are making their names by creating eating regimes for their lactose/gluten/pick your food group-intolerant audience. So why the sudden craze for cutting out foods? Are there any health benefits (or risks), and what's the difference between a food allergy and a food intolerance anyway? Here's everything you need to know.

Allergy vs intolerance

"A food allergy involves the immune system," says Dr Isabel Skypala, a consultant allergy dietitian at Royal Brompton & Harefield NHS Foundation Trust. "With a food allergy, your body mistakes a particular food for a potential invader and reacts within two hours of eating that food (usually sooner), every time you eat it." Symptoms include nausea, vomiting, wheezing, rashes and anaphylactic shock. Intolerances are less specific and tend to cause symptoms such as bloating, diarrhoea and constipation, or tiredness. "The timescale of your symptoms may vary, you may not always react to a food or your symptoms may change depending on the combination of food you're eating."

Amena Warner from Allergy UK adds,"An allergy is very definable, potentially life threatening and fairly straightforward to diagnose, whereas intolerances don't involve the immune system. They're much more vague and could range from severe bloating or diarrhoea to somebody just having a feeling that a particular food 'doesn't agree' with them. And they generally don't tend to be life threatening."

The only exception to this rule is coeliac disease, which is an autoimmune disease caused by an adverse reaction to gluten (a protein found in wheat, barley and rye). "Unlike other food allergies, the symptoms of coeliac disease aren't always immediate, but it falls under 'allergies' and not intolerances because it involves the immune system, which reacts to gluten," says Dr Skypala.

What are the most common types?

 

Coeliac disease affects one in 100 people - however, of those, only 24% of sufferers know they have it, meaning half a million people in the UK have coeliac disease and don't even know about it. Symptoms include bloating, diarrhoea, nausea, wind, constipation, unexplained tiredness, mouth ulcers, unexplained or sudden weight loss and a red, raised rash (often with blisters) on the elbows, knees, bottom or face (this is known as dermatitis herpetiformis, or DH). 

 

 

"Other allergies include fish and shellfish, usually prawns, nuts, milk and eggs, but the last two are very rare in adults and more common in children, who then usually grow out of it," says Dr Skypala. "Then there's pollen food syndrome, or oral allergy symptom, which occurs in adults who are sensitive to tree or grass pollen. This happens when the body wrongly recognises foods, such as fruits and nuts, as pollen and reacts."

 

Common food intolerances are to wheat (found in bread), dairy (eg milk, yoghurt and cheese), and fructose (the sugar found in fruits). Symptoms include bloating, diarrhoea or constipation, nausea, tiredness and a general feeling of sluggishness

 

How can you be tested?

According to Dr Skypala, with an allergy there's no grey area: "A blood test or skin-prick test will give you a positive or negative result and you'll then be given guidance by a dietitian." But don't be tempted by a home-testing kit: "They're inaccurate, they're not regulated and they're potentially dangerous," she says. "Unless you see your GP or a specialist allergy professional, such as a doctor or nurse, you're just wasting your money."

Nutritionist Amanda Ursell agrees: "If you think you have a food allergy, see your GP right away, who can refer you to a medically qualified allergy expert. Don't opt for one of the alternative therapy-style tests available online, such as kinesiology or hair analysis."

As for food intolerances, Dr Skypala says there's no specific test. "It's just a matter of cutting the suspected food out of your diet for four weeks and if your symptoms improve, you may have one. However, this has to be done under the care of a dietitian. Don't try to cut things out yourself, or because you've read something about food intolerances online - the information there is often poor, old or inaccurate."

Is there a cause - or cure?

According to the experts we spoke to, there's no known cause for allergies or intolerances, but recent studies have found that being exposed to a wide variety of food when you're a baby can actually protect you from allergies. "New research shows that exposing babies and young children to nut protein can actually reduce their risk of developing a nut allergy in the first place," says Dr Skypala. [But check with your GP first, as your child will need an allergy test and to be evaluated - and never give peanuts or whole nuts to children under five, for risk of choking].

"As for other causes, it's still largely unknown why some people develop food allergies or intolerances. Some studies suggest it could be because we're getting cleaner, or there's more pollution, but we don't really know. Although there is research that shows some conditions, such as coeliac disease, may be genetically inherited. There's also some research that shows the quality of our food can help prevent allergies and intolerances, so eating a wide range of fresh, in-season fruits and vegetables may help reduce your risk."

Are they on the rise?

"It does seem like more people than ever are suffering from food allergies and intolerances, and the 'free-from' range in supermarkets is getting bigger than ever, but in reality there are no accurate figures to pinpoint exact numbers," says Ursell. "According to the British Dietetic Association, around 3% of adults have a food allergy, although 20%
think they do. And I'm sure the figures are higher with food intolerances." 

A word of warning

Before you start browsing that ever-expanding 'free-from' aisle, a word of advice from Ursell: "While food allergies and intolerances are very real and potentially dangerous, it's important to remember that most people don't have them. Yet there seems to be a commercialisation of exclusion. One problem is that there is a lot of advice online from non-experts who recommend cutting out one food group or another. Some of them may have a genuine diagnosis, but many others may be hiding eating disorders behind a veneer of diet exclusion. Or simply not know what they're talking about. So be aware of who you're following, and question how qualified they are to be telling anybody to cut out food groups. And be really honest with yourself - are you thinking about cutting out bread because you have a genuine digestive problem, or because you want to lose weight or get a flatter stomach?"

Ursell says you also need to be wary of cutting out a food group without replacing it with another to make up for the nutritional shortfall. "Take dairy intolerance, for example," she says. "If you decide to stop drinking cow's milk because you think you're intolerant, then you need to be aware of what you're doing. Calcium, which is found in milk, cheese and yoghurt, is really important for bone and teeth health, especially in your twenties, when you're still building up your bone density. So if you take cow's milk out of your diet, you need to think carefully about what to replace it with. Almond milk is a great source of calcium, yet oat milk isn't.

Carbs are another food group that is commonly excluded, but again you have to ask yourself whether you're doing this for vanity reasons or because you genuinely think you have a real intolerance? While fat and protein can be broken down by the body to provide energy, carbs are a really great energy source. Even white bread has health-boosting calcium and B vitamins, and wholemeal bread has them, plus fibre. So don't cut out a fantastically nutritious food such as bread for no good reason."

Lastly, Ursell says that self-diagnosing can be potentially life threatening: "If you think you have coeliac disease, you should continue eating gluten and see your GP. If you give up gluten, or start swapping regular pasta for gluten-free pasta, but still keep small amounts of gluten in your diet, and then you see your GP, you may get what's called a 'false negative' result. If you don't get the right result and continue eating gluten despite having coeliac disease, you could go undiagnosed for several years, which could have harmful consequences.

If you have symptoms, such as constant bloating or diarrhoea, you should see your GP rather than cutting out bread, as there is a chance it might not just be an allergy or intolerance. It's unlikely that anything will be seriously wrong, but as illnesses such as Crohn's disease and ovarian cancer share similar symptoms, you need to rule out potentially harmful diseases before tinkering with your diet."

What can you eat instead?

If you're avoiding dairy
"Drink almond milk," says Ursell. "And eat more dark green leafy vegetables, which are a great source of calcium." To get your yoghurt fix, try Coyo Vanilla Dairy Free Coconut Milk Yoghurt (available in supermarkets and health food stores).
If you're avoiding fish or shellfish
Fish is a fantastic source of omega-3 fatty acids, which you can get from flaxseeds or flaxseed oil too (both are great on salads).
If you're avoiding eggs
"Some people with an egg allergy have to avoid it altogether, while others can tolerate foods containing well-cooked egg (such as cake) without a problem," says Warner. "And unlike chronic (incurable) allergies, such as coeliac disease, you can grow out of it." In the meantime, buy egg-free versions of mayonnaise, quiche and cakes. Or try a vegan cookbook (such as Deliciously Ella: Awesome Ingredients And Incredible Food That You And Your Body Will Love).