Why Are Food Allergies Increasing More Common


Wondering why food allergies seems so much more common now than they did 20 years ago? Jessica Snyder Sachs, author of Good Germs, Bad Germs, explains how our increasingly tidy lives can actually make us more vulnerable.

Q: What causes a food allergy?

A: There’s a lot of mystery about why one person develops allergies and another doesn’t, but I can tell you what immunologists understand about how allergies start. Our immune system doesn’t just react to some things and ignore others; it turns out that it reacts to everything it’s exposed to. In the gut, there’s this whole system of recognizing harmless substances. Food is supposed to be in that category, but with a food allergy the immune system sees the substance as dangerous. In some ways, the resulting histamine reaction is like that triggered by a parasite. With a mild food allergy, that might involve cramping and diarrhea. But a severe food allergy can trigger life threatening anaphylaxis.

Part of what I explore in Good Germs, Bad Germs is why food allergies were so rare but have become epidemic in proportion. One of the most compelling and convincing arguments is that in the last five to ten years, immunologists have discovered that the body’s interaction with harmless germs calms the immune system. In our modern lifestyle, over the last 200 years in developed countries, we’ve more and more distanced ourselves from living in this sea of harmless bacteria. The less our immune system is exposed to that, the more it tends to remain on a hair trigger. Now, many more people develop allergies of all kinds.

Q: Is it the entire developed world or North America in particular?

A: Developed Western Europe is not that different from North America. A lot of people in North America do mistake food intolerance for food allergies. For example, relatively few people are actually allergic to milk; but many people can’t digest it. This whole epidemic of allergies – and not just food but also respiratory allergies – really started in the Scandinavian countries. Not coincidentally, those were among the first countries to adopt indoor plumbing because of their climate. There seems to be a connection there.

Q: Do you have any insight into why particular foods seem to trigger a reaction? For example, why the peanut is giving so many people problems?

A: I’m not an immunologist. But, basically, certain types of proteins grab the immune system’s attention more than others.

Q: Are food allergies ever reversible?

A: That’s the big thing right now. For years, with respiratory allergies, you could go for desensitization treatment to encourage your immune system to see what was bothering you as something harmless. That’s always been very tricky in the area of food allergies because you don’t want to trigger a life threatening anaphylactic reaction. Some immunologists are trying to deal with it, and some children do outgrow food allergies. But we don’t have a cure for food allergies, no.

Q: Is there anything you can do to minimize the risk that you or your children will develop food allergies?

A: In Good Germs, Bad Germs I followed researchers that looked at this from the perspective of our lack of good bacteria. People always think of bacteria as causing disease, but evidence suggests that really less than one percent of them cause disease. In looking at why we have these new epidemics of allergies I looked at the science showing that kids who are exposed to a lot of harmless bacteria early in their lives – whether because they went to daycare or lived on a farm with livestock or ate a lot of food fresh out of the ground instead of processed foods – have a much lower rate of allergies. Scientists are now looking at exposing both children and expectant mothers to probiotics (good bacteria) in an effort to reduce the likelihood that allergies will develop. The results haven’t been dramatic, but it suggests that it helps a little.

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