The lowdown on food allergy and intolerance: In conversation with Dr Stephen Taylor
Stephen L. Taylor, Ph.D., co-founder of the Food Allergy Research and Resource Program at the University of Nebraska, Lincoln, has spent his life studying food allergies, allergen detection and management, and says he finds it “disturbing” that so little money is being pumped into prevention, or accurately determining the scope of the problem.
Speaking to FoodNavigator-USA as part of our Food Allergy & Intolerance special edition, Dr Taylor said: “The only significant funding is being spent on finding cures for food allergies, rather than investigating the causes. There’s some funding via NIH, but that’s going into sponsoring desensitization research, such as that conducted by the Consortium of Food Allergy Research [CoFAR-funded studies so far have focused on exposing infants to eggs and peanuts], not prevention.”
He added: “Most experts believe that the prevalence of food allergy is rising in the US (click HERE), and the severity of reactions also seems to be increasing as well, which is worrying, but we actually do not have good data because a proper epidemiological study has never been funded or performed in the US and no one is officially responsible for collecting the data, which is why you see so much variation in the numbers.
“We have good data on young children going to specialist allergy clinics, but that’s not to say we know what is happening in the overall population, and I can’t point you to a lot of cold hard clinical peer-reviewed published data that provides accurate data on the prevalence of food allergies in the US.”
(Click HERE to see some estimates on food allergy prevalence from FARE, NIAID and the CDC.)
I don’t think physicians in the 20s or 30s would have missed dead bodies
That said, you don’t need to be a rocket scientist to work out that things are changing, he pointed out.
For example, you’d expect to see severe or fatal reactions to peanuts reported in the medical literature going back a few decades, even if children were not routinely tested or diagnosed, and you just don’t see it, he said.
“I’ve searched the clinical literature for reports of fatal reactions and I don’t think physicians in the 20s or 30s would have missed dead bodies. You see the occasional report of a milk allergy death, but if you’re looking for peanut allergy deaths you won’t find them. So did they not exist, or were they just not reported? It seems like someone would have reported anecdotal cases at least.”
"Most experts believe that the prevalence of food allergy is rising in the US, and the severity of reactions also seems to be increasing as well."
There’s no validated biomarker or diagnostic test for non-celiac gluten sensitivity
The good news is that awareness of food allergies has increased considerably in recent years, coupled with our understanding of the immune system, added Dr Taylor.
“There was a time when food allergies used to be dismissed as a kind of psychosomatic phenomenon, but I’m not sure any physicians would jump to that conclusion as their first response anymore, and with IgE-mediated food allergies [in which reactions are caused by an allergen-specific immunoglobulin E (IgE) antibody that floats in the blood stream], the situation is reasonably good now in terms of diagnosis.
“With celiac disease the biomarkers are not as good, so you really need to do a gut biopsy of the small intestine to be sure, which is a very invasive procedure. As for non-celiac gluten sensitivity, while some clinicians still do not believe it exists, I’ve been around for too long to dismiss it, but there’s no validated biomarker or diagnostic test, so there are no accurate figures on prevalence.”
We know that almost a third of the population has a genetic predisposition to celiac disease, in that they have particular versions (DQ2 or DQ8) of a cellular receptor called the human leukocyte antigen (HLA). But why do only a fraction of those with this predisposition actually develop the disease? Read our interview with Dr Alessio Fasano to find out more.
In Israel, they eat lots of peanuts and they have almost no peanut allergies
So why are more Americans allergic to foods they apparently used to be able to consume without too many problems, and why are they experiencing allergic reactions when people in other countries where the same foods are widely consumed, are not?
Early exposure and weaning practices definitely play a key role, although they don’t explain everything, said Dr Taylor. “In Israel, for example, they eat lots of peanuts and they have almost no peanut allergies. A few years ago, a physician in London [Dr Gideon Lack at King's College London] observed that Jewish children in London had a very high prevalence of peanut allergy – 1.8%, whereas in Tel Aviv it was 0.17% - so what was going on?
“One thing he observed was that the Israelis loved this weaning snack [Bamba] made with peanut butter and fed it to their kids very early, which ties in with the results of the [2015] LEAP study
which showed that if you deliberately expose infants at high risk of peanut allergy [babies with severe eczema, an allergy to egg, or both] to peanuts in early life, they are far less likely to develop allergies.
“The American Academy of Pediatrics used to advise against exposing very young children to peanuts – despite the fact that there was no evidence for that recommendation, and they have since retracted it, but it will take a generation to reverse things.”
“Kids also often outgrow soy, egg, milk and wheat allergies but seldom outgrow peanut and tree nut allergies.”
Dr Steven Taylor, co-founder of the Food Allergy Research and Resource Program at the University of Nebraska, Lincoln
Early exposure to peanuts reduces the risk of allergies
So in the case of peanut allergy – and possibly other allergies, he says, weaning habits are a hot topic – as it seems that early exposure to potential allergens means we may be more likely to develop a tolerance.
“I think it’s probably a very significant factor in the rise in food allergy and maybe even in the rise in severe food allergy.”
But there are also other factors at play that might explain why people in some countries consume peanuts or other foods without apparently experiencing allergic reactions, so it’s just not possible to pinpoint one reason for the changing data, he stressed.
For example, in China, where peanut allergy does not appear to be a big issue, observed Dr Taylor, “they eat mostly boiled peanuts, whereas in the US they eat more roasted peanuts and one of the most potent allergenic proteins in peanut kernels comes out of the peanut in boiling water and gets thrown down the drain, and that’s probably important.”
"I was on the Codex panel that came up with the big eight allergens; if I had to do it all over again I’d probably drop soybeans off the list.
"I think there is enough evidence to set thresholds for more allergens in the US aside from gluten. In Australia there are reference doses to guide precautionary labeling, and it would be nice to see that in the US."
Dr Steven Taylor, co-founder of the Food Allergy Research and Resource Program at the University of Nebraska, Lincoln
Gut bacteria and food allergy and autoimmune disorders
More generally, he said, there’s emerging research that suggests that gut bacteria could play a role in explaining why some people develop food allergies, although it’s still in the very early stages and it is far from clear whether attempting to manipulate the composition of one’s gut bacteria though the use of pre- or probiotics, for example, might reverse or attenuate the problem [although there is some promising research in this field].
The gut flora of people with celiac disease - an autoimmune disease that damages the villi of the small intestine and interferes with absorption of nutrients from food - is also different from those without it, according to Dr Alessio Fasano, a pediatric gastroenterologist and researcher at Massachusetts General Hospital, although we don’t know whether this is a coincidence, or if not, if one causes the other, or vice versa.
According to Dr Fasano, the timing of our initial exposure to gluten also appears to be important, with some data suggesting that infants fed gluten too early (2-4 months) have a greater likelihood of developing celiac disease, but other data suggesting that we shouldn’t leave it too late – indicating there might be a ‘sweet spot’ or window of opportunity when it is best to start adding gluten to the diet.
“The problem is that there is very little money being spent on food allergy research in the US and that’s pretty disappointing to me. If we just let things go on at the rate they seem to be increasing, it’s pretty disturbing.”
Dr Steven Taylor, co-founder of the Food Allergy Research and Resource Program at the University of Nebraska, Lincoln
Cesarean births, antibiotics, and the hygiene hypothesis
A connected issue is the rise in cesarean births in many countries (in which babies are not exposed to the bacteria in the mother’s birth canal, and grow up with gut bacteria that differs from that of babies born via vaginal delivery), said Dr Taylor.
“I think the increase in cesareans is a factor [in the rising prevalence of food allergies], and clearly the intestinal bacteria play a role. There’s also evidence for the hygiene hypothesis [which suggests that modern medical practices such as immunizations, antibiotics and a more sanitary environment have weakened our immune systems]. If you live in an urban environment we know you’re more likely to develop food allergies than if you live in a rural environment, especially if you are close to animals, particularly farm animals.
“But it’s still just a hypothesis. The problem is that there is very little money being spent on food allergy research in the US and that’s pretty disappointing to me. If we just let things go on at the rate they seem to be increasing, it’s pretty disturbing.”
