It seems that food allergies are everywhere these days and that almost everyone has one. That’s not the case, but they are undoubtedly on the rise, affecting over 10 million people in the U.S. alone. What’s more, food allergies are not just found in infants and children. A growing percentage of adults contract food allergies and they are getting them later in life. What’s the allergy epidemic all about and are the dangers overblown? Dr. Vincent Ho, an expert on food-related allergies and the author of The Health Baby Gut Guide spoke to WellWell recently about the rise of food allergies, their threat and how best to treat the problem.
There are about 20 million people in America who have food allergies—about 6 percent of adults and roughly 6 percent of young children. Is that what we would see worldwide?
We know that food allergy rates are generally similar around the world. In Australia and New Zealand, about 10 percent of infants will have a food allergy, and anywhere from 4 to 8 percent of children will have a food allergy. With adults, probably one in every fifty will have a food allergy. That’s about on par with the figures in the United States. In both the United States and countries such as Australia and New Zealand, the number of people with food allergies is on the rise. We know there’s a doubling in each of the last few decades. There is something in the environment that seems to be linked to the rise in allergies, at least in the Western environment. It is a very common problem.
How serious are food allergies?
Allergies can be potentially very serious. Anaphylaxis is probably the most serious response that someone can experience. Anaphylaxis occurs when there’s exposure to an allergen, like peanuts, wheat or milk. There are quite a number of common foods which are allergens. What happens with anaphylaxis is a life-threatening reaction. Typically, symptoms might include difficulty or very noisy breathing, tongue swelling, tightness in the throat, wheezing or persistent cough. It can lead to rapidly lowering blood pressure, shock and even death. Peanut allergy is a very common food allergy. About one in 50 children and about one in 200 adults have one. Peanuts can cause anaphylaxis and death. One in every 200 episodes of anaphylaxis will lead to death. About 150 children die from food allergy and anaphylaxis in the United States every year. One child that passes away is one child too many.
Peanuts are one of the foods most likely to create an anaphylactic reaction. Are there other foods in the same danger zone?
We know peanuts, tree nuts and shellfish can lead to quite serious reactions. Typically, when it comes to particular foods like milk, egg, wheat and soy, those allergies tend to resolve in childhood in the majority of cases. The good news is that for some of those foods, you can outgrow it. However, other types of allergies like peanuts, tree nuts and seafood, those reactions generally persist throughout someone’s lifetime.
Is there a group within that infant to 12-year-old range that is most at risk from serious food allergy reactions?
Adolescents are the age group that has the highest frequency of fatal reactions. It’s the adolescent group that is the most at risk. There are several reasons why that might be. For infants, after birth, there is a reactivity, but this reactivity quickly dampens down. There will be a subgroup of young children where that reactivity will persist. We have to watch and be very mindful about it. Their allergies are usually managed very well by their parents. Up to the age of eight, children rely very heavily on their parents to manage their food allergies. But after that age, as they progress into adolescence, they become more aware of the difficulties of managing it. Often, they are instructed to manage their allergies themselves. As they get a bit older, there are some beliefs that they can misalign, leading to riskier behaviors as the adolescents try to assert their independence.
Is it a matter of awareness that people have these problems or is it rising because of something in the environment or with our gut health?
There is an increased prevalence of allergic diseases, not just food allergies but other allergies. This rise has been steady since the beginning of modern industrialization and it tells us there’s something in the environment that seems to be helping to shape susceptibility to allergies. The hygiene hypothesis, contrary to popular belief, doesn’t mean that you should disregard personal hygiene and become a sloth and hope somehow that makes you less likely to get allergies. In 1989, epidemiologist Professor David Strachan published in the British Medical Journal the results of a survey of more than 17,000 British children to help understand what could be behind the increase in hay fever in post-war Britain. He found that the children with older siblings were less likely to develop eczema by the age of 1 year and hay fever by the age of 23. He recognized there was some protective effect that the older siblings were passing on to the younger child. Along the way, something is being conferred from the older sibling to a younger one that seems to protect against allergies.
Professor Strachan felt this specific protective effect was exposure to microbes. Early childhood exposure to microbes can protect against the development of allergies by affecting the development of the immune system, and that’s what the hygiene hypothesis is about. It’s about exposure to these particular microbes, protecting against the development of allergies by maturing or affecting the development of the immune system. The concept of the hygiene hypothesis was latched by the scientific community. Some inflammatory molecules are involved in this process called cytokines, which are important for getting rid of bacteria inside our cells. If you’ve got a vigorous inflammatory response, that can cause some tissue damage. As a way to counteract, there are other protective cytokines, which are anti-inflammatory and help to fight off parasites, for example. If you’ve got a vigorous anti-inflammatory response, it can help promote allergy. Promoting allergic response is favored by the widespread use of antibiotics in the industrialized lifestyle. Those are the sorts of things that can help the promotion of allergy. And there are things that help protect against allergies, like the presence of older siblings, early exposure to daycare, household pets, childhood infections and exposure to a rural farming environment.
What about the foods themselves? Is food processing impacting food allergies?
The short answer is yes, although the evidence isn’t all that clear. We do know that certain aspects of industrialization are involved in the processing of food. For example, exposure to herbicides used in agriculture has been linked to the rise in allergies. It’s been shown with the data sets associated with allergies. Pollution has been linked to allergies, so there are factors in our environment that are associated with allergies. Sometimes, it’s difficult to identify what that is, especially when it comes to modern food manufacturing processes. Because there are a lot of chemicals used, it’s difficult to isolate which chemical is linked to allergies. In general, we can make some observations that exposure to herbicides and pesticides can be linked to a rise in allergies.
Are food allergies established at a very young age or can you develop food allergies as you mature?
There was this myth that food allergies were pretty exclusive to infants and young children. Adults are also susceptible to the development of allergies, and this is an important point. Adults with no history of food allergies can unexpectedly develop them. There was a survey of more than 40,000 adults published in The Journal of the American Medical Association. This research found nearly half of adults who reported being allergic to a certain food or ingredient developed the allergy in adulthood. About 11 percent of adults reported having a food allergy. Adult-onset food allergies represent about half of those cases. Adult food allergies are more common than previously believed and tend to be more severe compared to allergies developed during childhood.
Do we know why this is occurring, and what type of allergies?
It’s not entirely clear why this is occurring. It relates to factors in the environment. In the Western world, we are living in a cleaner environment, and as a consequence, there’s going to be less exposure to those microbes that were present in the past. These microbes were known as what we call the Old Friend microbes. These Old Friend microbes have been around for a long time. But with modern industrialization, we don’t have access to those modern microbes anymore. There is a hypothesis going around that adults pay more attention to personal hygiene compared to young children. They tend to be more vigorous about cleanliness and that’s a good thing. But at the same time, it means less exposure to some of those Old Friend microbes that are thought to be protective against allergies. We consequently adopt more personal cleaning practices, and this may be the reason why there’s a rise in adult-onset food allergies. Allergies also tend to be more severe compared to allergies during childhood. When children are very young, their immune systems are maturing, particularly in the first few years of life. The reaction is going to be less than a mature immune system. That’s the thinking behind the severity of an allergic reaction.
Is it true there are about 175 foods that tend to cause allergies?
If you look at very specific ingredients, you’re in the ballpark. 90 percent of food allergies would actually be limited to about 8 or 9 different foods. Those foods are egg, peanuts, soy, fish, shellfish, tree nuts, milk and wheat. Those are the really common ones that account for more than 90 percent of food allergies.
Do you trust what restaurants are saying to you?
Before going to a particular restaurant, let them know in advance about food allergies and any dishes that should be avoided in particular. There’s potential for cross-contamination. For example, someone has a peanut allergy. In preparing a dish, avoid the use of any peanuts. If the utensils used to prepare that dish are also used to prepare another dish, there can be cross-contamination. You can’t 100 percent reduce that risk, but there are things that we can do sensibly to help alert a restaurant to the possibility of a reaction. When adults go out, they can cautiously touch test a small amount of food on their outer lip before putting it into their mouth. If you get a warning symptom such as burning, tingling or swelling, that should alert you to the possibility that a food allergen is present.
Would you assume someone who is susceptible to a food allergy would know to do this?
Young children with allergies certainly are monitored very closely by their parents. Around 12 to 14 years old, adolescents should be able to not only recognize anaphylaxis symptoms but should also be able to carry an epinephrine autoinjector. The epinephrine autoinjector administers epinephrine, which is lifesaving for anaphylaxis. When they asked parents about when they expected their child to be able to manage it, most parents felt that kids should be self-managing at an earlier age. By six years old, children should be describing anaphylaxis. Anywhere between six to 11 years, they should be using an epinephrine autoinjector. Parents may have an assumption that their children should be able to be self-efficacious when it comes to managing their allergies at an earlier age.
Parents with young children must be under a lot of stress when it comes to allergies, especially since the vast majority don’t have a medical background.
Even though I have a medical background, I’m by no means immune to the stress that’s involved. I can see why parents would be very concerned about even trying certain foods on their infants for the first time. It’s not unheard of for parents to give their infants peanuts in their car just outside the hospital just in case there’s a reaction. They can rush their kids over to the emergency. There’s a lot of anxiety out there.
What about treatment? What do we see on the horizon and how can people protect themselves against food allergies?
There is a type of treatment called immunotherapy, particularly relevant to peanut allergies. Peanut allergy immunotherapy focuses on building tolerance to peanuts. The treatment helps to desensitize the body to the allergen, which is the peanut. You start by exposing the child to a tiny amount of peanut protein. Then, you expose it in gradually larger amounts until you hit a target dose. By building up the peanut exposure slowly, it can help desensitize the patient to high doses of peanut protein. It’s a treatment but not a cure for peanut allergy. It’s designed to help reduce the frequency and severity of allergic reactions. In the United States, the FDA has approved an oral immunotherapy for a particular type of peanut powder in a capsule for children with peanut allergies between the ages of four and 17. When it comes to research, there’s a lot of excitement about sublingual immunotherapy, taking a tiny amount of peanut protein under the tongue where it’s absorbed by the body. Some recent research shows that it is a very safe type of treatment.
Over a decade ago, the consensus was that children were at risk of developing peanut allergies because of family history and should avoid peanuts until they turned three. At this stage, they should have a more mature immune system. This strategy failed to prevent peanut allergies. There was some research done eight years ago in the United Kingdom called the LEAP. It helped change the way we think about exposing infants to peanuts in the first 12 months of life. This study showed that if you ate peanuts in the first 12 months of life, a significantly smaller proportion of children with a peanut allergy at the age of 5 compared to if you avoided peanuts.
What are some of the misconceptions that people have about food allergies?
There are a number of myths about food allergies. The most common one is that food allergies aren’t serious. They can be life-threatening with anaphylaxis. Another myth is that eating a little bit of a particular food won’t really hurt. The problem is that even a trace of food allergens can trigger a severe reaction in someone who has a food allergy. You’ve got to remove that allergen completely from the diet to stay safe and to live well. Another myth is that each reaction will get worse and worse. The reality is that food allergy reactions are unpredictable. You can’t predict how your body reacts to a food allergen the next time. In some cases, it can get worse, but it may not be the case. One should always be prepared with emergency medications, such as an EpiPen. The other myth I often see is that food allergies are the same as food intolerances. Food allergies are driven by an immune response to produce an antibody called IgE when it detects a food allergen. The IgE fights against food allergens by releasing chemicals such as histamines. Food intolerances such as lactose intolerance don’t involve the immune system. They can certainly cause some discomfort with symptoms like bloating, gassiness and diarrhea, but they’re not life-threatening. A food allergy can be fatal. There’s a big difference between food intolerances and food allergies.
About Dr. Vincent Ho
Dr. Vincent Ho is a clinical academic gastroenterologist and senior lecturer at the School of Medicine, University of Western Sydney. He is also a practicing gastroenterologist and a frequent contributor to The Conversation, where his articles have been viewed over five million times. He is also the author of The Healthy Baby Gut Guide: Prevent Allergies, Build Immunity and Strengthen Microbiome Health From Day One. He lives in Sydney, Australia.
The Healthy Baby Gut Guide can be purchased at Amazon.
