Why allergies and gut health are getting worse

Written and produced by Andrea Brody.

“There's evidence that we're definitely more allergic than we were,” says Theresa MacPhail. “If you just look at prescription data for percentage of the overall population, you can see that growth in things like inhalers or EpiPen prescriptions have increased fourfold over the last few decades. So that's a pretty good indication that something more serious is happening.” Graphic by Gabby Quarante/KCRW

For those dealing with allergies, the discomfort is all too familiar. Whether it’s stomach distress triggered by consuming nuts, dairy, or gluten, or the wheezing, runny nose, and watery eyes from exposure to pollen or animal dander, allergic reactions can be incapacitating.

This hypersensitive reaction of the body's immune system to otherwise harmless substances is the cause of hay fever, asthma, eczema, hives, and potentially life-threatening anaphylaxis. 

 While today we have a better understanding of allergies and we have access to antihistamines, EpiPens and allergy shots, there’s still no cure for allergies. Despite advances in medicine, allergy sufferers are on the rise. Approximately 30% to 40% of the world's population now reports some kind of allergic reaction.

What’s happening? Does our modern environment manufacture more allergens? Or are our bodies weaker and becoming hyper-sensitive? Medical anthropologist Theresa MacPhail, who has spent years researching allergies says, “We are seeing that our immune systems are getting overloaded. What we're seeing is just a lot more of everything, and a lot more severity… people who maybe had mild allergies are now having a bit more trouble than ever before.”

In her book Allergic: Our Irritated Bodies in a Changing World, MacPhail examines the history and science behind allergies. “At first they thought maybe allergies were [the] immunity gone wrong,” MacPhail says but scientists later realized that the immune system “in addition to protecting us could actually harm us. That was kind of a revolutionary thought at the time because when we first discovered the immune system, we thought it could only do one thing and that's to protect us.”

Why are more of us suffering from seasonal allergies? MacPhail thinks it could have something to do with the change in our climate. “The sheer amount of pollen in the air in the spring is tipping the scales. We have more mold allergies because climate change has led to wetter weather in some places and wildfire smoke is terrible in terms of asthma,” she says.  

MacPhail says it’s not just an overload of external allergens. “A big component in this story is that at the same time that our external environment was changing, we were accidentally reshaping our internal environment. I have people come up to me at book signings and events all the time saying ‘I'm 70 and now I can't eat shrimp. I've eaten shrimp my whole life, what's going on?’” 

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In her book "Allergic: How Our Immune System Reacts to a Changing World," Theresa MacPhail says it used to be “if you don't have an allergy by the time you're 40, you're just not going to have it. Now we know that's patently false.” Theresa MacPhail, pictured here, offers some practical tips. “We want to try to keep the microbial world around us in check but we don't need to carpet bomb [bacteria]!” Photo courtesy of Theresa MacPhail. 

If you have children, MacPhail urges you to get a dog. Early exposure to “different types of bacteria to the child at a young age” is beneficial and  “studies have shown that children that grow up in barns are the most protected.” If cleanliness is your concern, relax. According to MacPhail, you should “be conscious of the microbes around you and remember that they're not all bad.”

But not everything can be linked to an overuse of Lysol and climate change. Our modern diets, which often rely on processed foods, is also a contributing factor. The result of eating a less robust and nutritious diet has impacted our gut microbiome and “accidentally starved some of the beneficial bacteria that we need.” 

Can bacteria offer a solution? How is our immune system strengthened by the millions of microbes living on and inside our bodies? Evolutionary biologist and science writer Alanna Collen explores the significance of the human microbiome in her book 10% Human: How Your Body's Microbes Hold the Key to Health and Happiness.

“Most often, we are talking about the gut microbiome because that's where most of the microbes that we have live,” says Collen. “There are about 100 trillion microbes in us, in total, and most of those are in the large intestine and the colon. But we also have them all over our skin, in our lungs [and] everywhere.” 

Microbes and bacteria play an important role in our overall health, says Collen. “The reason they're so important is because they interact with our cells, and particularly our immune systems, and that is via the gut… The immune system pretty much underlies everything about our health, from our weight to how we feel to whether we have allergies or autoimmune diseases and so on.” 

Collen explains that “our bodies have had to adapt to the microbes that have chosen to live in us and it's us messing with them now because of our modern lifestyles and modern medications and the things that we expose them to. That’s causing the ill health problems that we have now.” But there’s some good news. It’s possible to rebuild a healthy microbiome by increasing the amount of plant food we eat.  Collen recommends adding a variety of different plants. “Don't forget that plants aren't just fruit and vegetables. It's also grains and lentils and beans,” she says. 

In her book “10% Human: How Your Body's Microbes Hold the Key to Health and Happiness,” author Alanna Collen argues that  many of our modern diseases like “depression and anxiety have gone much higher in recent years.” Alanna Collen, pictured here, says that the microbes that live in our bodies nurture us. "It's a symbiotic relationship where they give us things and we give them things. We give them protection, we give them food and they give us an awful lot more than we realize in terms of tuning our health.”

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  • Theresa MacPhail - Medical anthropologist; associate professor of science and technology studies, Stevens Institute of Technology; author of “Allergic: How Our Immune System Reacts to a Changing World”
  • Alanna Collen - Evolutionary biologist; science writer; author of “10% Human: How Your Body's Microbes Hold the Key to Health and Happiness.”


Andrea Brody