We spoke to the author of the new book, Allergic, about what’s behind the rise.
I grew up in Sacramento, which, when I lived there, was called the “City of Trees.” (They rebranded a few years back, as part of some marketing ploy, to “Farm to Fork Capital” — a slogan which, in my opinion, sucks.) Anyway, for people like my sister, the most trying part of living in the City of Trees was the springtime, when clouds of pollen would drift down from the city’s lovely variety of oaks. When March came ’round, she’d start sneezing, her eyes would water, and she’d be congested clear through June. She looked and sounded miserable.
But alarmingly, she says that her hay fever only seems to have gotten more intense in recent years, and that her daily dose of Zyrtec doesn’t provide the same relief it used to. I’ve heard the same from others, too. Medical anthropologist Theresa MacPhail, Ph.D., explores this curious rise of allergies in her new book, Allergic, and she’s got some bad news to share: Yes, allergies really have gotten worse — and things are only expected to go downhill from here.
Climate change has supercharged the spread of common allergens like pollen and ragweed, she tells us, and things have gotten so bad that even people who’ve never had allergies before are starting to get irritated. We spoke to Dr. MacPhail about what else is driving the phenomenon, why food allergies have become more common, and whether a new class of medication can provide hope for allergy sufferers.
Katie Couric Media: In your book, you write about how allergies seem to be more common, and that one of the reasons could be climate change.
Dr. Theresa MacPhail: For respiratory allergies, there’s a huge connection with air pollution and particulate matter, which tends to irritate our lungs. If you live close to a highway or a bus depot or factory and you’re breathing in a lot more particulate matter, the rates of asthma go through the roof.
The other thing with climate change specifically is with all that pollution, you’re pumping out CO2 and nitrogen. That’s warming the planet, obviously, but a lot of plants like all that extra CO2, so in a weird way, it’s good for the plants. Ragweed is a great example: A lot of us are allergic to ragweed, and ragweed happens to love excess CO2. It just thrives in it.
The other factor is that all this pollution is raining nitrogen into the soil. All plants need nitrogen to grow, and usually there’s only so much of it available in soil, but now, there’s so much that there’s no limit to plant growth. So what we’re seeing is just a lot more plants that we’re allergic to, and pollen seasons are also getting longer because the temperatures are warmer. The pollen loads are increasing and the pollen itself is changing, too. It’s becoming a bit more foreign to our bodies, so you’re gonna have a bit of a stronger reaction.
It’s not just climate change, though: You write about some other factors, like invasive species, that are making our allergies worse.
In the West, one of the huge problems is Bermuda grasses, which are invasive. It’s just gotten out of control. If you’re in Arizona or New Mexico or Southern California, you’re exposed to Bermuda grasses, which produce more pollen. Or there’s the Chinese Elm, another invasive species. They have a different growing season than most elms, so if you’re allergic to elm pollen, that may extend how long you’re going to have to take your Zyrtec. It could also trigger allergies in people that have never had them before.
Are there specific regions in the U.S. that are becoming particularly bad for allergies?
It’s across the map. In the north, the difference can be really dramatic — plants are blooming up to a month earlier, in February rather than in March. Or instead of having a killing frost in September or early October, the growing season extends into late November. In the southern regions, you’re getting hotter and more humid weather, which is causing a lot more problems with mold allergies. The mold is a little bit out of control in places like Louisiana, Texas, Florida; they’re having a lot more problems with fungal allergies. Even the desert isn’t immune. They’re having a huge problem with imported olive trees, which produce a lot of pollen. Desert areas especially are getting more and more allergenic, because of invasive plants where they didn’t used to be.
Are there any new allergens that have emerged lately that more people seem to be reacting to?
More and more people seem to be developing a problem with sesame in the last 10 or 20 years. We’re also starting to see an issue with alpha-gal, or the meat allergy, which we only noticed in the early 2000s. That’s caused by a bite from a lone star tick. What happens is that one of these ticks will have a tasty meal on a deer. And deer, us… all red meat has alpha-gal, which is a sugar. The tick will then attach to a human, and a little bit of its former meal gets injected into us. So what researchers think happens is that the tick saliva and the alpha-gal alerts the immune system that alpha-gal is not OK, so the next time you have a hamburger or hot dog or pork chop, you get hives, an upset stomach, or start vomiting.
What’s behind the rise in food allergies, especially among kids?
Unfortunately, part of the answer is we were giving bad advice for decades. When we started to see a spike in food allergies, we began to recommend that parents avoid giving their children anything that was allergenic until they were about 3 years old. It turns out that’s the exact wrong advice. Younger children have more malleable immune systems, so if they’re exposed to certain foods while they’re young, tolerance can be trained and learned. But past the age of 3, our immune systems are very hard to change.
So in 2016, the advice changed. Parents are now urged to introduce things like peanuts as early as six months in very minute trace amounts to see if there’s gonna be a problem. It’s not perfect. Some kids will still react, but it has at least lowered the rate of peanut allergies significantly.
The other answer is the microbiome. It looks like there’s a big connection between the composition of our guts and food allergies. Our diets have changed, we get too much fat, too much sugar, and not the same levels of fiber. That’s altering the composition of bacteria living in our guts.
You write that pollen levels are expected to increase over the next decade or so. Does that mean allergies are going to get even worse?
I hate to be the bearer of bad news, but yes. Everyone thinks that climate change’s effects on the human body are going to be 10 or 20 or 30 years down the road, but I’m here to tell you it’s here — it’s happening now. Our pets are having the same problems we do: They are literally the canaries in the coal mine, since our canaries are getting allergies, too. So humans are altering not just our own immune systems, but starting to alter our companion animals’ immune systems.
Are researchers developing new, more-effective medications to treat this rise in allergies?
It’s been a long, slow process, partially because there hasn’t been adequate funding. Until about the 1990s when food allergies started to spike, research funding into allergies was almost nothing. So we’ve really only had about three solid decades of working on it, and the treatments haven’t changed much until recently; there’s antihistamines, steroids, and immunotherapy.
But there’s a new class of drugs, called biologic drugs, coming out. These drugs are made from living cells that are starting to work more precisely than a steroid, which is sort of like a sledgehammer: They just turn off the entire immune system to stop the reaction temporarily. What these new drugs are doing is targeting a specific reaction in that chain of events that happens in your body when you have an allergic reaction. So it doesn’t depress the immune system as much, and they tend to have fewer side effects.
And what about for run-of-the-mill issues like a runny nose or itchy eyes?
Nope, we’re still behind the eight ball. There’s a new class of antihistamines that make you less tired and do less damage, side-effects wise. But they’re still operating through the same mechanisms as Benadryl or other common drugs. Everything we have now just deals with the symptoms once you’ve already developed the allergy. But all the researchers I met said that we really need to figure out how to induce tolerance, so that you don’t have the problem in the first place.
Do you have any advice for somebody who has really bad allergies, beyond just taking their antihistamines?
It’s really tough because the best thing is avoidance. But if you’re allergic to multiple grasses and trees, that’s not really feasible. The researchers that I talked to said the best thing you can do is see an allergist, because there might be some medications you’re not on that would help. Otherwise, if you have a really bad pollen allergy, try to take a shower immediately when you get home, because just walking through the air, you’ll be covered in microscopic particles. It’s also a good idea to change clothes and take a shower right when you walk in the door if your pollen allergies are severe.
