An increasing number of American adults are developing new allergies, particularly to food and seasonal allergens, later in life, according to medical experts. Data indicates a significant rise in both food and seasonal allergy diagnoses among adults, prompting concern and a call for greater awareness of early warning signs.
Recent studies reveal that nearly half of U.S. adults with food allergies developed them after the age of 18. Furthermore, analysis of private insurance claims between 2007 and 2016 showed a 377% increase in food allergy-related anaphylaxis treatment claims, with a substantial portion involving individuals over 18.
Physicians suggest that environmental and lifestyle changes, rather than genetics, are the primary drivers of this trend. Leading theories point to disruptions in the gut microbiome caused by diets high in processed foods and low in fiber, which can impair the gut barrier and increase susceptibility to allergens. The "hygiene hypothesis," suggesting that cleaner environments may prevent the immune system from learning to tolerate allergens, also plays a role. Additionally, environmental pollutants are scrutinized for their potential to disrupt epithelial barriers and promote allergic inflammation.
For certain allergies, like shellfish, which is the most common adult-onset food allergy, cross-reactivity with other allergens such as dust mites and cockroach proteins is a key factor. The body's immune system may begin to flag common foods as threats, initiating a gradual build-up of allergy-related antibodies over time.
Subtle Warning Signs of Developing Allergies
Before a severe reaction like anaphylaxis occurs, the body often displays subtle warning signals. These can include mild itching of the tongue or throat after consuming a specific food, a symptom that may persist for months or years as the immune system ramps up its response. Other initial indicators can manifest in the mouth, such as swelling of the lips, tongue, or mouth, which may precede more severe respiratory issues. This oral allergy syndrome, linked to proteins similar to those in pollen, is often mild and may be mitigated by cooking the food.
Gastrointestinal symptoms can also be an indicator of a developing allergy. Nausea, cramping, or diarrhea following food consumption can signal the release of histamine, a chemical released by immune cells when the body mistakenly identifies a harmless food protein as a threat. This is a hallmark of a developing allergy and can lead to symptoms like itching, hives, and swelling.
In some cases, particularly with Food Protein-Induced Enterocolitis Syndrome (FPIES), a rare food allergy that does not involve typical IgE antibodies, reactions can be delayed. Instead of immediate anaphylaxis, FPIES can cause severe vomiting, diarrhea, and abdominal pain, often driven by T-cell responses. While more common in children, adult-onset FPIES is being increasingly reported, with seafood being a common trigger in adults.
Climate Change and Allergies
Seasonal allergies are also striking adults later in life with surprising frequency, largely attributed to climate change. Rising temperatures are extending pollen seasons, increasing pollen production, and making allergens more potent. Research indicates that pollen seasons have lengthened significantly since 1990, leading to increased pollen concentrations and more intense allergic reactions. Pollutants, such as ozone and diesel exhaust, can act as "adjuvants," priming the immune system to overreact to allergens by damaging epithelial barriers in the airways, skin, and gut.
Experts recommend identifying and avoiding known triggers as a primary strategy for managing allergies. For those with severe allergies, allergy shots may be a viable treatment option to gradually desensitize the immune system. Antihistamines and nasal sprays can also help manage symptoms. Awareness of one's body and prompt action when a reaction begins are crucial for preventing severe health consequences.