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SOUND BODY

When food hurts

From milk to nuts, we often blame allergies for ailments that follow. If only we knew for sure.

Brett Nasuti Brett Nasuti took part in a study that slowly introduced him to milk. (Gretchen Ertl for The Boston Globe)
By Stephen Smith
Globe Staff / June 7, 2010

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This much she knew for sure: Her baby, her firstborn, was in agony.

Robyn Nasuti watched with alarm as her son’s skin crusted over in rashes again and again, his nights bereft of sleep. One day, a nibble of his father’s birthday cake erupted into hives, a swollen face, a trip to the emergency room.

No one could figure out why young Brett kept turning so sick.

Then, at the age of 10 months, he went for an operation to repair a cleft palate. His mother told a nurse about the rashes and the swelling.

“The nurse said, ‘You should have him tested for food allergies,’ ’’ Nasuti remembers. “And I said, ‘What’s a food allergy?’ ’’

That was 11 years ago. It’s a question that’s still hard to answer.

In the years since Brett Nasuti was diagnosed with allergies to milk, wheat, almonds, and 12 other items, there’s little doubt that food allergies have reshaped the medical, social, even political landscape. This week, for example, Massachusetts health regulators are expected to order restaurants to plaster warnings on their menus about food allergies.

But a federally commissioned study released last month reached a sobering conclusion: After a decade of banning peanuts from schools and creating dairy-free havens, there’s scant uniformity in how food allergies are diagnosed, few good treatments, and no standard definition of what, exactly, a food allergy is.

In many ways, food allergies are the Rubik’s Cube of the allergy world, Byzantine and endlessly frustrating. They’re a reflection of our complex, dependent relationship with food. Unlike other allergies — think hay fever — we can’t close a window or use a vacuum cleaner to whisk away the culprit.

And they highlight the enigmatic machinations of the human immune system. It remains a mystery why, in some people, the immune system responds like a fly swatter to a food allergen while in others, the cavalry is summoned, cannons blasting.

“The bottom line is we’re just not smart enough,’’ said Dr. Dale Umetsu, a Children’s Hospital Boston allergy specialist. “We don’t fully understand what’s going on. It’s a confusing area.’’

If there’s a knowledge gap among the specialists, the chasm is even broader among patients.

Surveys have shown up to 30 percent of Americans believe they’re afflicted with food allergies, perhaps because of misdiagnosis or misunderstanding. But the study that appeared in May in the Journal of the American Medical Association — an analysis of years’ worth of food allergy research — concluded a truer prevalence figure lies between 1 percent and 10 percent.

“Food is blamed for a wide variety of problems that may have nothing to do with food,’’ said Dr. Marc Riedl, head of the clinical allergy branch at the University of California-Los Angeles medical school. It’s understandable, he said: “Most people eat three times a day at least.’’ So food is easy to pick on.

Even if food really is the cause, that doesn’t mean the sufferer necessarily has an allergy.

It could instead be a food intolerance — and that’s not a matter of gastronomic semantics. Consider what happens when some people sip from a glass of milk. Their abdomens roils. They endure bouts of diarrhea or vomiting. It heralds lactose intolerance, caused by a shortage of the enzyme that processes the sugar in milk.

A food allergy is something different.

Take the same glass of milk and give it to someone with a milk allergy. In that person, the body’s army of disease fighters — the immune system — recognizes something in the milk as foreign and rebels.

“It’s one thing for the immune system to recognize something as different or dangerous, but if you bring to bear too much firepower, you’re going to get severe symptoms,’’ said Dr. Matthew Fenton, chief of the allergy branch at the National Institute of Allergy and Infectious Diseases.

But the symptoms of food allergies, food intolerance, even food poisoning can overlap. So how does an allergy wind up being the prime suspect in that rogue’s gallery of misery?

There’s no definitive, easy-to-administer test — nothing like, say, a fingerprint — to tell patients they have food allergies. A blood test can identify a certain kind of immune system warrior, and a skin test, which involves injecting trace amounts of the suspect allergen under the skin, can provoke a response.

Here’s the rub: Not everyone with a positive test develops symptoms.

“People perceive a test as either right or wrong,’’ said Dr. Jennifer Schneider Chafen, lead author of the study that appeared last month and a researcher at Stanford University and the VA Medical Center in Palo Alto, Calif. “That’s the great confusion with the diagnosis of food allergies in the general population.’’

Doctors should augment tests with an exhaustive personal history to reach a diagnosis. So if a patient reports breaking out in hives after every peanut butter sandwich and has a positive blood test, that’s where Marcus Welby and Perry Mason meet to derive a confident diagnosis.

In some cases, specialists resort to what’s regarded as the gold-standard allergy exam, known as a food challenge. Patients are given a smidgen of the food that’s thought to make them sick and observed. Because of the risks — including anaphylaxis, a severe reaction that can lead to death — it is conducted only in medical offices capable of resuscitating patients.

There’s no denying food allergies seem more common today than a few decades ago — just about everybody knows somebody whose kid turns allergic with even the smallest bite of strawberries, eggs, or some other common food. “That’s another big puzzle,’’ Umetsu said. “When I was a kid, hardly anybody had a food allergy.’’

Specialists disagree on whether food allergies are truly more prevalent or if they’re just being documented more faithfully. And if there is an increase, the reasons for that remain murky, with doctors pointing to a brew of environmental and genetic factors. Maybe, they hypothesize, it’s because children aren’t exposed to as many germs as they once were and, thus, the immune system doesn’t learn early in life how to properly gauge its response.

Despite increased awareness of food allergies, spending on research by the federal allergy agency is barely $20 million a year.

At MIT, a chemical engineer is trying to build a better allergy trap, hoping to spare others the stress friends met when their son was initially tested for tree nut allergies and had equivocal results. “It just makes you live with this constant state of fear,’’ assistant professor Christopher Love said.

The technology he’s developing evaluates white blood cells from patients and hopes to identify with greater precision which parts of the immune system are responding most forcefully and in the greatest numbers. That knowledge could then help doctor and patient come up with better ways of stopping the allergic reaction.

But even with a faster, clearer diagnosis, patients wouldn’t have much to choose from in the way of treatments — beyond eliminating the troublesome food. But researchers are experimenting with gradually introducing allergic patients to the foods they now avoid, sometimes modifying proteins. Essentially, they’re hoping to teach the immune system not to get so angry when it sees the allergen.

Brett Nasuti, whose 5-year-old brother Nicholas was diagnosed with 16 food allergies, outgrew most of his — but milk remained a major threat. He was so sensitive that a kiss to the cheek from someone whose coffee carried a splash of milk would produce a ruby lip-shaped welt.

Last year, he joined a study at Children’s that slowly introduced him to milk; the trial initially included injections of a medication that aims to prevent life-threatening reactions.

It worked. Today, Brett must drink a glass of milk every day — whether he wants to or not — so that his body’s tolerance will remain fortified.

“The idea,’’ his mother said, “that he could actually go to a party and have a cheeseburger and not worry about whether the bread has milk in it is just wonderful.’’

Stephen Smith can be reached at stsmith@globe.com.

Is it an allergy?


A study released last month examining years’ worth of research found that self-reported allergy rates were higher than what was identified in diagnostics such as blood and skin tests.

Milk
Self-report: 3.5%
Tests: 0.6%-0.9%

Egg
Self-report: 1.3%
Tests: 0.3%-0.9%

Peanut
Self-report: 0.75%
Tests: 0.75%

Fish
Self-report: 0.6%
Tests: 0.2%-0.3%

Shellfish
Self-report: 1.1%
Tests: 0.6%

SOURCE: Journal of the American Medical Association