TOKYO - Adult food allergies are on the rise in Japan, with increasing numbers of people reporting symptoms after eating foods they once tolerated without issue. Recent findings reveal an unexpected cause behind many of these cases: hay fever.
Medical specialists have noted a growing trend of adults developing allergic reactions to certain fruits, vegetables, and seafood. These reactions can include symptoms such as itchy mouths, swelling of the lips, throat discomfort, and even respiratory distress occurring hours after eating. In many cases, these symptoms are traced back to food items like apples, peaches, raw shellfish, and spices.
One explanation lies in the phenomenon of cross-reactivity. Pollen allergies, such as those caused by birch, cedar, or ragweed, can prime the immune system to react to structurally similar proteins found in food. For example, people allergic to birch pollen may experience symptoms when eating apples, while those sensitive to mugwort or ragweed might react to carrots or melons. This cross-reaction occurs because the immune system mistakes the food proteins for pollen allergens and mounts a defense, resulting in an allergic response.
Skin prick tests and blood tests are commonly used to identify specific food allergens. In these tests, small amounts of allergen extracts are applied to the skin or analyzed in the blood to detect immune responses. Results often show sensitivity to multiple foods, particularly raw items such as oysters, scallops, and clams. Heating these foods can sometimes break down the allergens, making them safe to eat.
According to a government-backed survey involving over 1,000 allergy specialists, the number of adults seeking medical attention for food allergy symptoms increased by approximately 1.5 times over a three-year period. While food allergies in children are often linked to milk, eggs, or wheat, those in adults tend to involve fruits, vegetables, and seafood.
Despite the rise in adult-onset food allergies, there is currently no definitive cure. Managing the condition typically involves identifying and avoiding trigger foods, especially when the body is under stress, fatigued, or affected by alcohol, as these factors can worsen allergic reactions.
As allergies become more prevalent—now affecting nearly one in two Japanese people—the development of new treatments is gaining urgency. Researchers are working on an innovative new drug that targets mast cells, which play a key role in allergic reactions. These cells release histamine and other substances when triggered by allergens.
The new compound, named MD501, works by reducing the number of mast cells themselves rather than just suppressing the substances they release. Originally studied as an anti-cancer agent, the drug was repurposed for allergy treatment after researchers realized it could interfere with mast cell survival.
Laboratory experiments on mice showed a marked decrease in mast cell populations after administration of the drug. Similar results were observed in human-derived cells, offering hope for a more fundamental approach to allergy control.
While MD501 has not yet entered clinical trials, researchers are hopeful that it could be made available within the next five to ten years, providing a much-needed breakthrough for those living with persistent food and pollen allergies.
Source: YOMIURI
