Visit SPECIAL ISSUES: FOOD & AGRICULTURE for photos and more information.

Normally, the body's immune system defends against potentially harmful substances like bacteria or viruses. But in some people, an immune response is triggered by a substance we generally consider harmless: a specific food.

For KLCC's Special Issues Series on Food and Agriculture, Tiffany Eckert examines the ins and outs of food allergies and intolerance.

Paul Stieber is a high school language arts teacher in Eugene. He's married, and the father of a one year old son. He's a happy guy now, but ten years ago-- his life took a painful turn.

Stieber: "I was about 28 years old when I began developing strange, un-curable symptoms -- this time in my life I was really active, I was running marathons--and had incurable diarrhea, anemia, and exhaustion."

After suffering these symptoms for a year, Stieber finally saw a gastroenterologist. It turned out he has celiac disease.

Celiac is an auto-immune response triggered by gluten. And, gluten, is a special type of protein commonly found in rye, barley and wheat.

In our small intestines live villi, little hair-like projections responsible for absorbing fluids. When a person with celiac disease consumes gluten, those villi flatten out --preventing their ability to receive crucial nutrients.

After Stieber found out he had this intolerance to a food, he says his first reaction was relief because it could have been a more troubling condition. But…

Stieber: "I felt defeated. Because I was, well, so young and rather indestructible and invincible. And realize I would have to make a lifelong change in terms of how I fed my body. And it wasn't an easy transition for me."

Carrie Janes is a nutritionist with Eugene's Village Health Clinic.

Janes: "What happens when people develop allergies or intolerances is really a defective digestive system."

Janes believes that, over the last few generations, people have consumed so many additives and genetically modified organisms, that our bodies don't really know how to process them.

Janes: "We have to start looking back and why is it? What have we done to our food supply?  What have we done to our own internal environment to make it so that we can't defend ourselves against these things like we used to be able to?"

The environment she speaks of is inside the gut. Janes says in a compromised intestine--some food particles can irritate the wall of the intestines --creating holes where allergens seep into the blood stream. This is called "leaky gut."

Janes: "Finding out what's stressing the system, removing those foods and then going back and healing the gut. If we don’t go back and heal the gut, we may develop other allergies later on."

Janes has seen a steady rise in the incidence of food allergies in her practice. Some specialists are skeptical about this trend.

Dr. Marc Riedl is an allergist at Ronald Reagan UCLA Medical Center. He co-authored a study casting doubt on the reported numbers of people with food allergies in the U.S.

The study found that between 2 and 10 percent of the population have true food allergies. But the number of people who think they have them is much higher. Dr. Riedl says self-diagnosis is eroding the definition of food allergy.

Riedl: "When we confuse allergy with other things we do a disservice both to patients who are affected by this serious condition but also people who are mis-diagnosed and basically changing their life based on bad information."

So, if you think you have an allergy to a certain food, Dr. Riedl says clinical evaluation is the only way to confirm it.

Riedl: "There are food sensitivities; there are food intolerances that may cause symptoms but that don't represent the same level of danger as a true food allergy."

Frequently food allergies start in childhood. Most kids will outgrow allergies to things like dairy or soy by the time they're about 5--as long as they avoid the offending foods until then.

But, allergies to foods like shellfish and peanuts tend to be life long.

Kashi Hughes is 9 years old.  The first time he reacted to peanuts, he was just a baby. (His mom says he swelled up and turned red as a tomato.) Kashi does remember a scary experience he had at a Thai restaurant.

Hughes: "The guy said 'no peanuts' but there ended up being peanuts and then so I was in an attack and I just remember feeling really itchy and really...can't breath that well."

That incident prompted his parents to get him an epinephrine shot to carry around-just in case. Kashi says sometimes its tough having to watch out for every food he eats.

Hughes: "Yea, at, like, birthday parties, you have to check if there's peanuts in the cake or not."

Kashi attends a public elementary school in Eugene. He says he isn't the only kid watching out for food allergens in the cafeteria. There are three tables designated "peanut free"... and they're always full.

American consumers have been grappling for years with food industry labeling practices. Paul Stieber recently went to England.

Stieber: "Europe is far more evolved on this issue. In London, I could go to their version of Safeway, Tesco, I believe it's called, and look at the labeling on a package and it would tell me if it contained wheat or gluten. In other words, if it was safe for a celiac to consume. I mean, come on!"

There has been an upsurge in the number of stores and restaurants in the Northwest catering to consumers with food allergies or intolerance.

Capella Market is a locally owned grocery in Eugene. On their shelves, every gluten-free product is identified with a blue dot. And there are about eleven hundred of them.

Store manager Rex Snellstrom gives us a tour...

Snellstrom: "We have rices, we've got box mixes pilafs, gluten free mac 'n cheese, rice pastas or corn pastas, quinoa..."

Nationwide, the gluten-free market has exploded. It's estimated to top 1.7 billion dollars in 2010. G-F items are typically much more expensive than their counterparts, but Snellstrom says that's starting to change.

Snellstrom: "We have at least five chocolate cake mixes and that kind of competition is going to drive prices down."

In the Willamette Valley, many food purveyors like Abby's Pizza and Chocolate Decadence, market products with food allergies in mind. There are even support groups.

With all the lifestyle changes Paul Stieber has made, he says two things will never be the same when they're "gluten-free"---beer and bread.

Stieber: "I mourned.  To be quite honest, I mourned it."

Nutritionist Carrie Janes reminds us there are ways to boost immunities to allergies. The gut requires a healthy level of good bacteria to do its job.  

Pro-biotics in homemade yogurt or lacto-fermented foods like sauerkraut help grow healthy flora in the gut and that promotes better digestion.

Janes: "Our bodies are meant to heal. They're meant to take in all this nourishing food and nourish us. But when we abuse it by eating these highly processed, nutrient deficient foods--we're not allowing our body to do what it innately wants to do."

And that is... to be well.

For KLCC News, I'm Tiffany Eckert.

Visit SPECIAL ISSUES: FOOD & AGRICULTURE for photos and more information.