Will a climate change induced prolonged ragweed season impact the prevalence or severity of food allergies? These studies tell us what's up.

Ragweed season is upon us and we are sneezing about it. It usually lasts from August through October, but as climate change continues, so change our seasons. Sniffling from seasonal allergies is no fun and the thought of having a longer seasonal allergy season is the opposite of what we want. But will climate change creating a prolonged ragweed season impact the prevalence or severity of food allergies?

Scientists know that the allergen content of ragweed pollen, for instance, increases as carbon dioxide (CO2) concentrations go up. Additionally, in high CO2 environments, poison ivy becomes more toxic.

But is our changing climate also impacting the allergenicity of plant-based foods?

Researchers Paul Beggs & Nicole Ewa Walczyk opened up the conversation in 2008 with their article, Impacts of climate change on plant food allergens: a previously unrecognized threat to human health. This article is the first to link food allergies and climate change. Beggs and Walczyk propose “impacts of climate change on plant food allergens are likely to have, and may have already had, impacts on human health.” 

Later, a 2016 study furthered this proposition by showing increased allergen concentration in peanut when grown under increased CO2 environments.  

Let’s break it down.

According to the Union of Concerned Scientists, three main factors related to climate change fuel increases in allergenicity.

  1. Carbon dioxide, the heat-trapping gas that is the primary cause of our warming planet, increases the growth rate of many plants. It also increases the amount and potency of pollen. (Remember, plants ‘eat’ carbon dioxide. They give us oxygen in return.)
  2. Rising temperatures extend the growing season and the duration of allergy season.
  3. And, an extended spring season alters the amounts of blooms and fungal spores that are known to exacerbate allergy symptoms. 

In other words, the longer the spring, the longer seasonal allergens (pollen) will be in the air. The longer seasonal allergens are in the air, the more likely you are to develop a food sensitivity or allergy.

More about pollen.

Beggs and Walczyk also suggested in 2008 that “impacts of climate change on pollen may lead to increased sensitization to food allergens.” In a journal article published in February 2018 entitled Climate change: allergens and allergic diseases, researchers confirmed that, “pollen allergy is also implicated in certain forms of food‐allergic disorders.” 

Furthermore, a 2013 study showed the relationship between peanut sensitization and geography, linking certain pollen exposure to increased sensitization. “Thus, it is likely that changes in climate that result in altered distribution of various allergenic plants may, in time, bring about a change in the pattern of food allergy, especially that caused by plant food allergens.”

As food allergies and climate change continue to be on the rise, the need for more research on this intersection is urgent. This is just the beginning. 

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