Microbes, Medicine, Modern Life May Drive Food Allergy Rise, Experts Say

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When Alice Hoyt, MD, was a child, she knew one peer with a food allergy.

Today, classes fill with several children managing food allergies—a trend Hoyt witnesses not only as Chief Allergist at the Hoyt Institute of Food Allergy, but also as a parent of children whose classmates have food allergies.

According to the US Centers for Disease Control & Prevention (CDC), the prevalence of food allergies has increased by 50% since the 1990s.¹ Health insurance claims show peanut allergy incidence in 1-year-olds tripled from 2001 to 2017.²

Approximately 33 million people in the US have a food allergy.¹ Among children, about 8.4 million are allergic to shellfish, 6.2 million to milk and peanuts, 3.9 million to tree nuts, 2.7 million to egg, 2.7 million to fin fish, 2.4 million to wheat, 1.9 million to soy, and 0.7 million to sesame.

Food allergies are more than tingling in the mouth, itching, and belly pain—they can trigger life-threatening anaphylaxis.¹ It also poses a financial concern, with annual costs estimated to be nearly $25 billion.

The BBC reported in October 2020 on the growing rise in food allergies and what might be at fault.³ Experts say that the rise in food allergy prevalence could be due to the hygiene hypothesis, greater awareness, caseation section, microbial environment, and vitamin D levels. HCPLive spoke with several experts to give a 2025 update on the potential causes and solutions regarding the rise in food allergies.

Hoyt explained that, in the 1990s and early 2000s, many believed children should steer clear of common allergens during early childhood. Experts now agree that this flawed guidance contributed to the rise of food allergies.

Although allergies were first reported in the 1800s, peanut and egg allergies were not recognized until the 1900s. Food allergy rates spiked in the 1990s, prompting an expert to advise delaying allergen exposure until the immune system was ready.

“Granted, this was expert opinion, not what we call now evidence-based medicine,” Hoyt said.

Guidelines in the early 2000s recommended avoiding cow’s milk until 1 year, eggs until 2 years, and peanuts, tree nuts, and shellfish until 3 years.

“There wasn’t good evidence for that, and then what we saw as a result of that delayed introduction of allergens is an even bigger increase in food allergy,” Hoyt explained.

This non-evidence-based mindset persisted until the 2015 LEAP study showed that an early introduction of allergens could reduce allergy development.⁴ The National Institute of Allergy and Infectious Diseases (NIAID) issued new clinical guidelines on January 5, 2017, recommending early introduction to peanut butter and peanut-containing foods as early as 4 – 6 months of age.⁵ Still, Hoyt said many questions remain about why food allergies are rising so rapidly.

“There are a lot of potential explanations, but we don’t really have one clear answer,” Joseph Hernandez, MD, PhD, a clinical assistant professor of allergy and immunology at Stanford University, told HCPLive.

Like Hyot, Hernandez mentioned that the outdated practice of delaying allergen exposure contributes to the rise in food allergies. Despite the guidelines changing in 2017, some clinicians still advise avoidance in early life.

He referenced the hygiene hypothesis, speculating that over the past 30 – 50 years, we are subject to getting fewer infections, and that could lead to the rise in allergies.

He also mentioned the role of the microbes in our environment. Strong evidence has shown that farmers who regularly interact with different animals have distinct microbiomes on their skin and in their gut—and are at much lower risk of developing food allergies.

Other contributors to microbial imbalance include increased antibiotic use and cesarean deliveries, which can alter a newborn’s microbiome. Environmental factors, such as pollutants, chemicals, and emulsifiers in our food, may impact people’s membranes, gut, and respiratory tract, increasing the likelihood of sensitization.

“All those have been proposed as hypotheses, but the data supporting all those is not strong,” Hernandez said. “It’s probably going to be actually multiple things that have led to the rise in food allergies and allergies in general.”

Another factor—climate change—could be affecting food allergy rates, however, there is little evidence on this. Rising temperatures boost pollen counts, and pollen sensitization may trigger food allergies, as some pollen resembles the proteins in food.

Hernandez added that part of the reported increase may stem from greater awareness and changes in diagnostic criteria. Over the last decade, allergists have become more conscientious about testing limitations and false positives. Allergists are less likely to do large panels of allergy testing for foods, either via blood or skin testing.

“That’s a lot less common, certainly amongst allergists, because we realize that there are fairly high false positive rates, and those false positives can lead to people avoiding the food that may actually then result in them having an allergy in the end, even though they didn’t necessarily when you first tested them,” Hernandez said. “There’s been a lot more emphasis on actually confirming diagnoses of suspected food allergies with food challenges, too, if there’s any uncertainty.”

Reports have shown greater food allergy rates in industrialized nations and among Black individuals, though the reasons remain unclear.^6,7 Hernandez reasoned this could be attributed to socioeconomic factors.

While there are still so many uncertainties about the causes and ways to deal with the rise in food allergies, psychologist Katherine Dahlsgaard, PhD, discussed ways to manage food allergy anxiety.

“What many allergists don’t know is that the avoidance is driving the anxiety,” said Dahlsgaard, a licensed psychologist and founder of Brave is Better LLC in Philadelphia. “Every time I have a new patient, I make a point of calling their allergist to consult with them about my treatment plan. Often, the allergist will say, ‘Well, I know that they’re over avoiding, but I feel like over avoidance is better than under avoidance, and we can all agree that under avoidance [means] you’re being unsafe. But what allergists don’t know is that over avoidance is dangerous in terms of just increasing, escalating, endless anxiety.”

So, with the rise in food allergies, where do we go from here?

Hernandez proposed studies on bacterial species, seeing whether bacteria as a probiotic supplement or metabolites from these bacteria could reverse or prevent food allergy development in young children. This would help identify the important roles of suspected exacerbating factors for the development studies. Hernandez noted that these trials would need to be government-funded and either very controlled or with a large sample of > 1000 participants.

He also pointed to policy and clinical interventions, such as regulating food additives, reducing C-sections, or minimizing unnecessary antibiotic use.

“Those are going to be very difficult to do—to actually prove that any of those interventions will make a difference in the rate of food allergies,” Hernandez said. “I think it’s going to be a real challenge.”

References

1. Food Allergy Facts and Statistics for the U.S. Food Allergy Research & Education. April 18, 2024. https://www.foodallergy.org/sites/default/files/2024-07/FARE%20Food%20Allergy%20Facts%20and%20Statistics_April2024.pdf

2. J. Lieberman, J. Sublett, Y. Ali, T. Haselkorn, V. Damle, A. Chidambaram, K. Rosen, T. Mahr, Increased Incidence and Prevalence of Peanut Allergy in Children And Adolescents in The United States, Annals of Allergy, Asthma & Immunology, Volume 121, Issue 5, Supplement, 2018, https://doi.org/10.1016/j.anai.2018.09.039.

3. Jones R. Why Food Allergies Are on The Rise. BBC. October 25, 2025. https://www.bbc.com/future/article/20201023-food-allergies-why-nut-dairy-and-food-allergy-are-rising. Accessed May 29, 2025.

4. Du Toit G, Roberts G, Sayre PH, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy [published correction appears in N Engl J Med. 2016 Jul 28;375(4):398. doi: 10.1056/NEJMx150044.]. N Engl J Med. 2015;372(9):803-813. doi:10.1056/NEJMoa1414850.

5. NIAID Guidelines for the Prevention of Peanut Allergy. Community Care. February 14, 2022. https://communitycare.com/niaid-guidelines-prevention-peanut-allergy/. Accessed May 29, 2025.

6. Prescott SL, Pawankar R, Allen KJ, et al. A global survey of changing patterns of food allergy burden in children. World Allergy Organ J. 2013;6(1):21. Published 2013 Dec 4. doi:10.1186/1939-4551-6-21

7. Johnson S. Food Allergies Take Uneven Toll on Black Children. US News. March 9, 2023. https://www.usnews.com/news/healthiest-communities/articles/2023-03-09/food-allergies-take-uneven-toll-on-black-children#:~:text=An%20estimated%201%20in%2017,7.6%25%20had%20a%20food%20allergy. Accessed May 29, 2025.