Is changing your diet the answer to food allergies?by Donna Chisholm
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As thousands of people eliminate whole food groups from their diet to tackle dairy or gluten intolerance, scientists are trying to better understand what’s going on in their gut.
It’s not that she doesn’t believe the test results, but she knows her stomach feels better, lighter and less bloated if she doesn’t have dairy foods. She well remembers the way her guts gurgled after she ordered a coffee with soy milk and got cows’ milk instead, and how gassy she felt after a cheese-topped pizza.
The science might say Novio, 23, doesn’t need to go dairy-free, but like many others, she’s going with her gut rather than the graphs.
Liggins Institute professor David Cameron-Smith, principal investigator on this year’s milk-gut comfort trial in which Novio was one of 40 young female participants, hopes the study will enable researchers to better understand the symptoms that are driving some people away from dairy. “There’s fire behind the smoke. Perceptions are real, so we have to not dismiss people outright but to understand it.”
Cameron-Smith, a professor of nutrition at the University of Auckland, says people who think they’re intolerant to one or more foods are likely to head down “a pathway of restrictive eating” unless they’re committed to focusing on the nutritional value of what they’re eating.
Preparing for tsunami
With food allergies and intolerance inexplicably on the rise, doctors are preparing for a tsunami of adult patients as an increase in paediatric cases flows through to adulthood. Dietitians and other nutrition experts say they’re seeing clients who are following ever-more-restrictive dietary regimes – often on the recommendation of friends or “Dr Google” – and putting their health at risk.
“What’s available to you if you walk down the dairy-free aisle or the gluten-free aisle of the supermarket may not be up to scratch simply because it makes statements about what it excludes,” says Cameron-Smith. “That doesn’t mean it’s healthier or better for you, and when you start eating a more restrictive diet, your intake of things like calcium and iron, in particular, really suffers.”
The Liggins study found that half the people who report having dairy intolerance can actually digest lactose and therefore don’t need to eliminate dairy foods that are much lower in lactose, such as cheese and yogurt. Lactose intolerance is a genetic condition that causes a lack of the enzyme lactase to break down lactose, a sugar found in dairy products.
Cameron-Smith says the study is trying to define the less-well-understood dairy intolerance, for which there is no objective test. Participants were divided into three groups – lactose intolerant, lactose and dairy tolerant, and dairy intolerant – and were challenged with drinks of lactose, lactose-free milk, ordinary milk and a2 milk before having blood, urine and breath tests and MRI scans to measure their reactions. The a2 results are not yet in.
The research found that for up to two hours after taking the lactose-free or ordinary milk, the group who were dairy intolerant reported more abdominal rumbling and bloating than the dairy-tolerant women, but they then improved. For the lactose-intolerant women, the symptoms became progressively worse over the three hours they were monitored.
Intriguingly, waist measurements of the women varied enormously after they drank the same amount of milk – some ballooned by 4-10cm within 30 minutes – but the increase did not correlate to their symptoms of gut discomfort.
In another unexpected result, Novio and a number of the other women had late-onset symptoms after the lactose challenge. Novio says she felt sick and suffered diarrhoea and a rumbling stomach about six hours after drinking it, but she was already home, so the symptoms couldn’t be monitored.
Mind a powerful influence
Cameron-Smith and Novio acknowledge that the mind can be a powerful influence on the body’s symptoms. “Maybe I’m subconsciously thinking it will make me feel sick,” Novio admits, although she’s adamant her symptoms were real.
They are, says Cameron-Smith. “What you report is what you perceive and what you have.”
The main allergen in milk is a protein known as beta-lactoglobulin, and it’s normally a reaction to this that causes milk intolerance in children, although they usually grow out of it as they age. Cameron-Smith says it’s not known whether some kind of low-grade immunological response might explain the gut symptoms of Novio and others.
“Immune cell release and localised histamine release can trigger a whole range of responses, but little is known of what occurs in the gut.”
Study leader Amber Milan, a nutritional scientist, says the dairy-intolerant women had slightly different symptoms to the lactose-intolerant group and they came on earlier. “They experienced quite severe symptoms 30-60 minutes after drinking milk, whereas in the lactose-intolerant group, the symptoms typically happened two to three hours later.”
This makes sense, says Milan, because lactose is normally digested in the small intestine by the enzyme lactase. If lactase is lacking, the lactose keeps going through the digestive system to the large bowel, where it’s processed by gut bacteria, producing gas and causing bloating, flatulence and possibly diarrhoea.
“Shot in the dark
Milan says the scientists are still evaluating the blood tests to determine whether the dairy-intolerant women have a common biomarker, and they are looking for markers of inflammation. But the work is very experimental. “The problem with biomarkers is we don’t know what we are looking for; we don’t know which ones are relevant, so it’s a shot in the dark.”
Another aim of the study is to discover objective measures of discomfort. Some tests, such as for breath hydrogen and galactose (which literally means milk sugar) in urine, already exist to measure how much lactose isn’t absorbed. The scientists are looking for what they call “breath volatiles”, hoping they can detect a chemical that matches discomfort scores for dairy intolerance the same way breath hydrogen matches lactose intolerance.
About two-thirds of people internationally are estimated to have some degree of lactose intolerance, with a higher prevalence in East Asia, so teasing out the differences between lactose and dairy intolerance has important ramifications for our dairy industry. The research is a collaboration between the University of Auckland and AgResearch, with funding from the High Value Nutrition National Science Challenge, The a2 Milk Company and the university.
Auckland dietitian and food allergy specialist Anna Richards says people who have an adverse reaction to milk “don’t really understand what the mechanism is” and assume they can’t have any dairy at all because they feel unwell after drinking a milkshake.
“For most of us who feel better not drinking a milkshake, the answer is just reduce your lactose and you’re fine, but the next thing you know, they say they have a milk allergy and they’re reading the back of every packet of crackers and avoiding anything that says ‘may contain traces of milk’. People are making their lives more complicated than they need to be.”
Not the same thing
Allergies and intolerance tend to be lumped into the same basket, but they’re not the same thing, she says. “Allergies are driven by the immune system, but there’s a whole range of other reasons why you may have an adverse food reaction that has absolutely nothing to do with your immune system.”
Richards’ 28-year-old daughter was recently diagnosed with coeliac disease – an auto-immune disorder that causes bowel damage in reaction to dietary gluten. As with dairy intolerance, there is no objective test for intolerance to gluten, but Richards regularly sees patients who unnecessarily eliminate gluten from their diet when they aren’t coeliac.
“It’s a bit like the milk thing – using a cricket bat when a fly swat would do. We see more of the worried well excluding whole food groups from their diet in Australia and New Zealand.”
For food providers such as restaurants and bakeries, that causes a blurring of the distinction between those with coeliac disease, who will become ill with any gluten at all, and those who might feel better if they ate a little less.
“One of the biggest issues for my daughter when she eats out is she gets asked, ‘How coeliac are you?’ Well, coeliac disease is like pregnancy, you either are or you aren’t.”
When she travelled in Europe, however, her daughter had no such problems. “There, they don’t have lifestylers excluding gluten. When she went to eat out in Italy, they knew what coeliac disease was and they knew she needed complete exclusion of gluten.”
There, she says, breads are still made out of what we’d call ancient grains and are typically sourdough risen over four to 24 hours.
“They buy bread three times a day, but that doesn’t fit our lifestyle. We want to buy a squishy loaf that’s going to be fresh for a week.”
Here, gluten is added to bread to keep it soft and moist for longer, and yeast helps it rise faster but gives the wheat, which contains the gluten, less time to break down.
“A significant number of patients of mine who say they don’t feel great on bread here then travel to Europe and can eat all the breads on offer.”
Tokoroa-based chef Jimmy Boswell, a “chef ambassador” for Coeliac NZ who says he’s been medically diagnosed as “non-coeliac gluten intolerant”, says restaurants usually fall into one of three groups: those that go “hard out” offering mainly gluten-free fare, those that try but can have cross-contamination issues, and those that don’t make a special effort.
It’s common for coeliacs or gluten-sensitive people to become ill because of cross-contamination during food preparation. “If you’re using normal flour and throw it down on a bench to roll pastry out, the flour dust in the air can take up to 20 minutes to settle and it can settle anywhere. With a coeliac, even a small amount can cause a huge reaction.
“It’s always happening – people talk about going to this place or that and getting ‘glutened’.”
“Lifestylers” who choose to go gluten-free can create confusion for eatery staff, says Boswell. “They insist on a gluten-free main, then have a sticky toffee dessert that is full of gluten, and some wait-staff and chefs go WTF? But I won’t put down people who’ve made that lifestyle decision. It’s their choice.”
Nutrition Foundation dietitian Sarah Hanrahan believes perceived issues with gluten are now “so mainstream” that many people are excluding it without even knowing what it is. “The Glen Innes Pak’nSave has a gluten-free aisle. That’s a very telling marker. It doesn’t get much more mainstream than that.”
She says industry egg promotion body Eggs Incorporated put out information saying eggs were gluten-free. “A few years ago, I would have said, ‘Of course they are, what a nonsense – gluten could never be in eggs.’ But very few people know it’s a protein that’s found only in certain grains [such as oat, wheat, barley and rye].”
An Eggs Incorporated survey found only about a third of those questioned were sure about what gluten was, a third thought they did and a third either didn’t know or “didn’t really” know.
Hanrahan says that until recently, adhering to a gluten-free diet would have been difficult and expensive, but now there are so many choices available that it’s far easier. “What people shouldn’t do is make the mistake of thinking a healthy diet is defined by gluten.”
Christchurch paediatrician and food allergy expert Dr Rodney Ford, author of The Gluten Syndrome, says diagnosing gluten intolerance is highly controversial, with gastroenterologists saying “if you haven’t got coeliac disease, you don’t have a gluten problem”.
“No one knows what quantity will make people ill. Some people are incredibly sensitive to it, while others can take a little bit more – maybe a slice of bread – before they get sick. Because there’s no test, the only thing to do is challenge-and-elimination tests.”
He sees many patients taking dietary restrictions to “ridiculous” levels. “I spend as much time coaxing people back onto foods as I do judiciously restricting foods.”
Food allergies drop in kids
The Melbourne HealthNuts study of more than 5000 children reported this year that the 11% prevalence of food allergies in one-year-olds drops to 3.8% by age four.
Auckland allergy specialist Dr Rohan Ameratunga says the figure for one-year-olds is much higher than what was seen in the past, but nobody knows why. Theories include the hygiene hypothesis and changes in the diet to include fattier or more refined foods. “I see kids allergic to eggs, milk, nuts, wheat, fish, the whole shebang, with very high levels on their allergy tests, which didn’t really happen in the old days.”
The lack of solid research here makes it difficult to quantify cases. “Unless a food allergy is really life-threatening, for people who are struggling it’s the least of their worries. They worry about putting food on the table, so it’s probably a big hidden problem in this country.”
Although most food allergies go away with age, increasing numbers of adults with persistent food allergy or intolerance symptoms are being referred for hospital-level care.
At the Auckland City Hospital immunology department, clinical immunologist Dr Anthony Jordan says food allergies are the No 1 condition the department deals with. “For our paediatric colleagues, it makes up a huge part of their work, but we see that trickling through into the adult years.” Numbers are rising and it’s only going to get worse, he believes. “There’s a tsunami of food allergy that hasn’t yet arrived to the adult department.”
The main food allergies, in order of prevalence, are cows’ milk, eggs, soy, peanuts, tree nuts, shellfish/fish and wheat.
Clinicians use a “whole person” approach to deal with issues of food aversion and anxiety. “If you are food allergic, you can develop food aversion long term even though the natural history of food allergy is to resolve [itself]. Say you and I are both peanut allergic at two, one of us may not be when we are 18, but over that time, behaviours and fears around that food can become well ingrained.” Doctors worry about that fear spreading to other food.
Treatment approaches have changed, says Jordan. “Ten years ago, if you came in and said, ‘I’m allergic to milk, I can only drink milk once a week and then I feel tired’, I’d tell you you don’t have a milk allergy and send you home. That would be the end of it. Now we would say, ‘Okay, why do you think you can have milk once a week and why have you established a link between milk and feeling that way?’”
Immunology department dietitian Sharon Carey says the patients she sees with food intolerance have a range of distressing symptoms, including gastrointestinal upsets, aches and pains, hives, swelling and fatigue. Her job is to find out what’s causing them.
She says it’s not difficult to determine who has a true allergy and who has intolerance, with an allergy response starting within minutes, usually generating intense itching, a rash and mouth, throat or respiratory symptoms, sometimes followed by anaphylactic shock.
Trigger for gut discomfort
Carey says she’s never found a robust piece of research proving that gluten intolerance actually exists – apart from its role in coeliac disease and a rare skin disorder. She believes issues with FODMAPS – poorly digested short-chain carbohydrates such as fructan in wheat, onions and leeks – are more of a trigger for gut discomfort. “A low-wheat diet can be helpful for some people, rather than a strict gluten-free diet.”
Carey, who’s trained in psychotherapy, says a big part of her job is “joining up what is happening in someone’s life with their symptoms. Meeting lots of people with [food] hypersensitivity, I knew this was about distress, about difficult lives, people under a lot of pressure, who have difficulties in expressing this.”
When patients are referred to the hospital for food intolerance, she says, emotional-life distress, sometimes serious, is going on “every time”. “The only time you wouldn’t see it is when someone has a true lactose intolerance. Again, there’s a lot of misconception. People can feel a bit yucky drinking too much milk but it’s not necessarily the lactose.”
The important issue, she says, is having a healthy relationship with food rather than being fearful of it. “It’s about understanding what’s going on here … why am I struggling to tolerate different things in my diet? Why do I need such control over my diet? What is that really about? As soon as that relationship becomes healthier, people become a lot more confident to eat more foods again.”
It’s also important to realise that the symptoms are real. “It’s not all in the head, so it needs to be taken seriously.”
Carey is seeing more of what she calls “orthorexia”, or disordered eating. “It’s not quite anorexia but the belief that we need to not eat soy, gluten or wheat, perhaps avoid carbs altogether, avoid milk … all these reasons to avoid food to be ‘healthy’. Cutting down on some of those foods might be healthy, especially saturated fat and sugar, but when we start getting anxious and obsessive about it, it’s no longer healthy. I’m recognising more and more people who are quite disordered in their eating habits but who started off eliminating foods to have a healthier diet or relieve symptoms.”
Her role is often to try to liberalise diets rather than restrict them, and she says people need the chance to work through what’s stressing or distressing them. “They are obviously getting some comfort from changing their diet or they wouldn’t be doing this, but I don’t think they are doing it for the right reasons.”
Christchurch food allergy expert Dr Rodney Ford offers this guide to common food-related disorders. He says they can be confusing because people often get similar symptoms from different food-reactive immune responses and can have more than one type of reaction simultaneously to different foods.
- Immediate food allergy: Usually driven by allergy-causing IgE antibodies to specific foods (only skin-prick testing or blood tests help with identifying this reaction).
- Delayed food intolerance: Often driven by the body’s immune response to foods through IgG antibodies.
- Gluten-related disorders: Gluten-intolerance and coeliac disease.
- Oral food allergy syndrome: Driven by IgE antibodies to specific pollens, cross-reactive to foods.
- Histamine intolerance: Caused by histamine-releasing foods.
- Food additive reactions: Symptoms caused by preservative, and colouring (E colour chemicals 102, 104, 110, 122, 124, 129).
- Natural chemical reactions: Caused by naturally occurring salicylates, amines, MSG in foods.
- Enzyme deficiencies: Lactose intolerance, congenital sucrase-isomaltase deficiency (CSID)
- Fructose intolerance: Inability to absorb because of deficient fructose carriers.
- FODMAP intolerance: FODMAPs are short-chain carbohydrates that aren’t well absorbed in the small intestine. The term is derived from fermentable oligo-, di-, mono-saccharides and polyols.
This article was first published in the August 19, 2017 issue of the New Zealand Listener.
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