By Katie Kerwin McCrimmon

An allergy epidemic has sent rates of food allergies, eczema, asthma and seasonal sniffles through the roof in the U.S. and other English-speaking countries since the 1950s.

But causes remain elusive. Could antibiotics or Tylenol be to blame? What about folate that pregnant women now routinely take? Or air pollution, cigarette smoking and climate change that has extended allergy seasons? Are we too clean and too careful? Should we be feeding our babies peanuts, eggs and milk much earlier than doctors have advised? And should we emulate the Amish, who have exceptionally low allergy rates and live in close proximity to cows and their manure?

While theories abound, we know remarkably little about causes for allergy spikes or how to prevent them. Researchers and allergists agree that we have changed something crucial or indeed many things. But what are the triggers that are fueling the allergy epidemic and how can we reverse course?

‘It has to be environmental’

“We are drowning in information and starving for knowledge,” Dr. Erwin Gelfand, chair of the pediatrics department at National Jewish Health, said paraphrasing a fellow scientist.

“There’s no doubt that the incidence of allergic disease has increased and it can almost be traced to five or six decades ago. The big question is, what changed? What allowed this to go on? How can it happen when it takes thousands of years for our genes to change? It has to be environmental,” Gelfand said.

He was among a panel of experts who gathered Saturday in Denver to describe the newest research on allergies during the annual conference of the Association of Health Care Journalists. The allergists said they and other doctors might have gotten much of their advice wrong for years.

In fact, research from one of the doctors who came to Denver could transform the treatment and study of food allergies with a much-awaited randomized controlled study due out later this year.

Dr. Gideon Lack is a professor of pediatric allergy at King’s College London and heads children’s allergy treatment at Guy’s and St. Thomas’ NHS Foundation Trust in London.

He hopes to give parents advice based on science since we have a striking dearth of knowledge.

“There are very few evidence-based guidelines on how to feed our children,” Lack said. “We can buy all sorts of beautiful dietetic books … and there is a huge industry there, but it is not evidence-based.”

Peanuts: friends or foes?

Lack shared his counterintuitive theory that feeding babies potentially allergenic foods like peanuts earlier, rather than delaying them as seminal groups like the American Academy of Pediatrics long have advised, might prevent rather than cause allergies.

Lack said that he, like nearly all physicians, used to warn parents about early introduction. And in fact, he avoided giving his own children peanuts.

“I bought into this. I was part of the establishment,” he said.

Then in about 2003, Lack spoke at a medical conference in Israel and happened to see a friend feeding her baby a teething snack full of peanuts.

“I was horrified. If she were living in the U.K., she would probably go to jail for this,” Lack joked at another talk he gave at National Jewish.

It turned out that parents in Israel commonly feed their babies peanuts as early as four months and peanut allergies are rare.

In contrast, rates of both eczema and peanut allergies in the United Kingdom have been soaring as they have been in the U.S.

“There’s an EpiPen in just about every classroom. This really has become an epidemic,” Lack said.

The trip to Israel triggered an idea for Lack. Could babies who have eczema be getting exposed to peanut proteins through moisturizing lotions and creams that commonly contain peanut oils? If these babies are not at the same time ingesting peanuts, could their bodies wrongly see peanut proteins as attackers?

As an allergy fellow, Lack had spent five years in Denver at National Jewish. He used to work in a mouse lab here and as part of research for his former teacher, Dr. Gelfand, Lack painted egg proteins on mice to help make them allergic. After the Israel trip, a light went off for Lack. In mice, he remembered that topical exposure to allergens could cause allergies while mice that were fed the same proteins did not become allergic. Perhaps, when it comes to peanuts, mice and babies were similar. Maybe eating potentially allergenic proteins can be protective.

Lack released the results of his first major study on early exposure to peanuts in 2008. He compared children in Israel to Jewish children in the U.K. and found that peanut allergy rates were up to 10 times higher in the U.K. where parents routinely delayed feeding peanuts.

The results were striking, but Lack knew other factors could be at play.

“There’s more sunlight in Israel, more Vitamin D. Maybe that’s protective.”

Or perhaps the Mediterranean diet and higher consumption of olive oil in Israel decreased allergy rates.

To truly test his hypothesis, Lack knew he needed the gold standard of science.

“The only way is to do a randomized controlled study.”

With funding from the National Institutes of Health in the U.S. and the Immune Tolerance Network, an international clinical research consortium, Lack in 2009 began the study — known as LEAP for Learning Early About Peanut Allergy — that is due out later this year.

He and his team found 640 infants, ages 4 to 11 months with severe eczema, egg allergy or both. After the flip of a coin, half the babies ate peanuts while half did not. Researchers have closely monitored the families. Parents fill out regular food diaries and researchers even vacuum up dust in their homes to determine how much peanut protein is floating in the environment. Like cat dander, Lack said peanut proteins stubbornly hang around the environment long after a person has consumed peanut butter, for instance.

The children in his study are now 5 and Lack and his team will compare their allergy rates.

He does not know yet how the study will turn out. Even his hunches change every couple of days.

“One day (I think) consumption will work, the next avoidance. Or maybe there won’t be a difference,” he said.

“We would like to think this has implications for prevention of egg, milk, tree nut and fish allergies, but we don’t know. We can’t assume that because it works in one group, it will work in another.”

Lack is also doing another study, known as the EAT study, in which he is probing whether exclusive breastfeeding or breastfeeding in combination with early exposure to eggs, peanut, wheat and sesame generates fewer allergies. Those results are due in about two years.

Food allergies and bullying

While the allergy world awaits Lack’s study results, doctors in the field like Dr. Dan Atkins, chief of the allergy section at Children’s Hospital Colorado, must cope with the realities of the allergy epidemic.

Along with physical problems, severe food allergies can cause psychological suffering including the little-known fact that many young patients get bullied.

“A third of these kids are bullied in school and a lot of times, parents don’t know,” Atkins said. “When I see young children, I say, ‘let’s pretend we’re in school and I’m a bully.”

He asks fearful young patients what will happen if someone wipes peanut butter on them.

“I’m surprised by the number of kids who say, ‘I’ll have an allergic reaction and I’ll die,’ ” Atkins said. “We’ve got all these kids running around with minor exposures afraid that they could die and that’s unfair. Now there’s a psychological component.”

To prove to skittish children and their parents that a small amount of peanut won’t kill them, Atkins sometimes wipes a bit of peanut butter on the child’s arm. Then they wait five minutes and almost always, the child is fine.

The newest trend in allergy treatment is to try to minimize foods kids can’t eat and, as soon as possible, to try to reintroduce potentially allergenic foods through what are known as food challenges. Doctors who know how to do them properly give kids a little of the food at a time so their body gradually can tolerate once harmful foods.

Of course if the child has a severe reaction, doctors can step in to reverse it.

When done properly, Atkins said food challenges are safe. As much as possible, he and the other experts said families and primary care providers should avoid restricting kids’ diets.

If a child reacts to 23 different foods, that doesn’t mean they’ll have severe reactions to all of those foods. He said parents and providers who don’t understand the complexity of allergies often fail to understand real levels of risk, which can be exaggerated.

“You don’t want someone taking them off of 23 foods. You can remove kids from too many foods,” Atkins said.

It may be that the famous “peanut-free tables” that have become de rigueur among ultra-careful parents and at schools struggling to cope with an onslaught of children with allergies could be unnecessary.

“Some kids want to eat at the peanut-free table. Others don’t because nobody sits with them. It’s a difficult, delicate balance,” said Atkins, who is also co-director of the Gastrointestinal Eosinophilic Disease Program at Children’s, where an interdisciplinary team is working on some of the newest emerging allergic diseases.

Both at Children’s and at National Jewish, doctors are finding that improper diagnosis and treatment of food allergies can actually harm children.

At National Jewish, Gelfand and colleagues see children from around the country whose cases have confounded doctors elsewhere.

“We see children who are on elemental diets who are failing to thrive and are cognitively behind because they’ve inappropriately been taken off of foods,” Gelfand said. “Food challenges suggest they can go back on (these foods).

“This is a big issue and it’s not an easy issue for primary care practitioners,” Gelfand said. “It’s time consuming (to make a proper diagnosis). That is difficult in the current medical system.”

Severe restrictions actually can harm babies and young children, Gelfand said.

“It can become an extremely dangerous situation that we all have to recognize,” he said.

‘A little dirt won’t hurt’

Along with early exposure to potentially allergenic foods, another of the most promising theories on the allergy front is that more exposure to bacteria and dirt could actually help us.

Doctors who first coined the term “hygiene hypothesis” found that in bigger families, younger siblings who were exposed to more illness and dirt actually had fewer allergies.

Another of the experts who spoke in Denver has been studying Amish communities in Indiana where he has found some the lowest allergy rates in the developing world.

Dr. Mark Holbreich, an allergist from Indianapolis, began offering free clinics for the Amish several years ago because they don’t have health insurance. He said some of his Amish patients thought they had allergies, but when he tested them, in fact, almost none did.

“I didn’t know what to make of it,” Holbreich said.

The Amish live on traditional farms without electricity, cars or modern conveniences. Pregnant moms drink fresh unpasteurized milk and work with cows and other farm animals. Children grow up in close proximity to dirt and get plenty of manure under their nails. (Click here to read a recent piece from the New York Times Sunday Review about Holbreich and his work with the Amish.)

“They’re living a life that Europeans lived 150 years ago,” Holbreich said.

He began collaborating with a European doctor, Erika Von Mutius, head of asthma and allergies at the Children’s Hospital at the University of Munich. She was studying traditional Swiss farm families and theorized that close contact with farm animals might have protective effects.

Holbreich became intrigued.

“As allergists, we spend our days treating them. We have no opportunity to prevent them.”

While allergy rates among Swiss kids who didn’t live on farms approached 50 percent, about half as many Swiss farm kids, or about 25 percent, tested positive on skin tests. Among the Amish, the rates were even lower: only about 7 percent.

“That’s the lowest prevalence of allergic disease of any population living in a westernized country that’s ever been reported,” Holbreich said.

Now, Holbreich and von Mutius are continuing to try to understand what about farm life is protective.

“Our current thought is that it requires exposure to large animals (especially cows). You need this rich microbial environment from the hay and the manure and everything else that’s floating around in the barn,” Holbreich said. “There’s something (too) about the milk that we don’t understand.”

Everyone drinks raw, unpasteurized milk, including pregnant women. Holbreich is careful to note that raw milk is not safe for people whose mothers did not drink it during pregnancy, so he’s not recommending that people run out and get raw milk.

But he’s trying to suss out the healthful effects from the milk and barn dust.

“I don’t think it’s a statistical aberration, but understanding it is hard.”

Complicating the Amish story is that similar traditional communities known as Hutterites conversely have high allergy rates similar to others in the U.S.

As Holbreich continues his work, he’s hopeful about the hygiene hypothesis: “A little dirt can’t hurt you. And maybe a little dirt can help you.”

So, what are the causes of the allergy epidemic?

The bottom line is that we don’t know. Our sedentary lives and sealed homes could play a role. One of the newest concerns is that high obesity rates can increase risk.

Along with causing other health problems, Gelfand said fat tissues can be “pro-allergic on the immune system.”

For now, some of the experts are owning up to their role in muddying the waters on allergies. Gelfand said that when peanut allergies started to rise, National Jewish doctors quickly started advising families to avoid peanuts. That may have been counterproductive for preventing allergies.

“This whole bit of advice that pediatricians and family practice doctors have been conditioned to give may have been totally wrong,” Gelfand said.

For now, he’s going back to advice Marie Antoinette might have given: “Let them eat dirt.” And he figures grandmothers everywhere are probably right: “A little dirt won’t hurt.”