Could Your Poor Health Be Due to Common Food Allergies?

That Discomfort? It Might Actually Be Caused by Food — The Relationship Between Common Foods and Allergies

When you feel "a bit unwell after eating" or experience "recurrent diarrhea and itching," do you ever think of food allergies? In recent years, the number of people with allergies in Japan has been increasing, and we've seen several cases where common foods were the cause. This time, we'll clearly summarize the characteristics of symptoms, easily overlooked foods, and methods for testing and coping.

Types of Food Allergies and How Symptoms Appear

Immediate-Type (IgE-Mediated): Reactions Appearing Quickly

Many food allergies cause hives, swelling of the face or throat, coughing, difficulty breathing, and in severe cases, anaphylaxis, within minutes to 2 hours after ingestion. This is a typical reaction involving IgE antibodies in the blood, and prompt action is necessary as it can be life-threatening if severe. Do not hesitate to seek emergency medical attention if you experience difficulty breathing or loss of consciousness.

Delayed-Type: Unpleasant Symptoms Appearing After a Time Lag

On the other hand, symptoms like diarrhea, abdominal pain, chronic skin itching, and fatigue can appear several hours to several days later, making it difficult to identify the cause. While tests measuring blood IgG antibodies are commercially available, there is debate among experts regarding their diagnostic certainty. Therefore, do not self-diagnose based solely on the results; consult with a doctor. We have seen cases where symptoms improved with a food diary and a gradual elimination diet (under medical supervision).

Adult-Onset and Cross-Reactions with Non-Food Allergens

Milk and eggs are commonly seen in infancy, but peanuts, shellfish, and tree nuts can persist into adulthood. Additionally, people with existing allergies like hay fever may experience Oral Allergy Syndrome (OAS) with foods that have similar structures to pollen. For example, people who react to birch pollen may feel itching in their mouth from apples or peaches, and those with latex allergy may react to bananas or avocados. Such cross-reactions have been noted by Harvard Health and Mayo Clinic, among others.

Easily Overlooked Allergens — Sesame, Processed Foods, and How to Read Labels

Sesame is an allergen that has gained attention recently, with increasing reports of it being a cause of food allergies in Western countries. Processed foods, such as sauces, seasonings, and snacks, can unexpectedly contain sesame or shellfish-derived ingredients. Therefore, if you suspect a link between symptoms and food, it's effective to check ingredient labels and inquire with manufacturers. In Japan, labeling of major allergens is mandatory, but there's also a possibility of contamination during processing or trace amounts, so individuals with a history of severe reactions need to be particularly careful.

Testing, Diagnosis, and Coping Strategies: What to Do

Consultation and Testing Process

• First, consult an allergy specialist or an ENT/dermatology clinic. A medical interview and a record of your diet and symptoms will provide clues for diagnosis.
• Skin prick tests and specific IgE blood tests are used to check for immediate-type sensitization. If a definitive diagnosis is truly needed, an oral food challenge (OFC) will be performed at a medical institution.
• Self-diagnosing delayed-type allergies with IgG tests is difficult to interpret, and we recommend discussing it thoroughly with a doctor before using it.

Daily Management and Emergency Response

Once the cause is known, avoid it by checking labels and confirming ingredients when eating out. For severe allergies, it's necessary to carry an epinephrine auto-injector (EpiPen) and ensure family and colleagues know how to use it. In our experience, keeping a food diary and then temporarily eliminating certain foods under a doctor's guidance has led to improvements in chronic gastrointestinal symptoms. However, it's crucial to pay attention to nutritional balance during elimination and consult with a doctor or nutritionist.

Summary

Food allergies are diverse, ranging from immediate reactions to those that appear after a time lag, and can change with age. Cross-reactions with non-food allergens like pollen and latex, as well as unexpected foods like sesame and "hidden ingredients" in processed foods, should not be overlooked. If you continue to experience concerning symptoms, we recommend consulting a specialist for appropriate tests and measures instead of self-diagnosing. We have seen many cases where individuals suffering from symptoms achieved improvement through testing and dietary management. Start by keeping a record.

Disclaimer: The information in this article is for general informational purposes only and does not constitute medical advice. Please consult a qualified healthcare professional before making any health-related decisions.